Major interaction on record — check this product against your medications before combining. Based on 7 of 11 ingredients. Check your meds →
Dietary supplement

Hard-AF Ingredients & Drug Interactions

by Steel

Hard-AF label
See full label image
Capsule Category: Other Combinations
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 9, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Hard-AF against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Major

Hard-AF is a dietary supplement by Steel with 11 active ingredients. Its ingredients are commonly taken for high cholesterol, vitamin b3 deficiency (pellagra), heart health support.Based on those ingredients, 1,416 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Yohimbine HCl, Epimedium brevicornum, Vitamin B3. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Hard-AF by Steel

Ask about any prescription or over-the-counter medication and we check it for interactions with Hard-AF by Steel — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Hard-AF by Steel

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Aug 6, 2026

What’s inside

Low disclosure
Ingredient Transparency · database check
Low

Most active ingredients don't disclose an individual amount — you can't tell how much of each you're getting.

Why this rating?
  • The label discloses an exact amount for 2 of its 11 active ingredients.
  • “Hard-AF Vertical Blend” is a proprietary blend — the label gives one combined amount (1.01 Gram(s)) without saying how much of each component you get.

Hard-AF contains 11 active ingredients in capsule form. Yohimbine HCl is extracted from yohimbe bark and affects your nervous system.

Vitamin B3 (niacin) is a B vitamin that your body uses for metabolism and nerve function. Maca powder, cassia cinnamon, Korean Red Ginseng, Eurycoma longifolia extract, and horny goat weed are plant-based ingredients traditionally used for vitality and sexual function.

Zinc is an essential mineral. The product also contains Byroviron, Kaempferia parviflora, and Capsorb—three ingredients we don't hold detailed data on.

The capsules are made with gelatin and contain magnesium stearate and silicon dioxide as inactive ingredients.

Does it work?

Leans against
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Leans against

The strongest graded evidence we hold for the stated purpose leans against a benefit.

Why this rating?
  • The label markets this product for: Erection formula for sexual performance.
  • We looked for evidence on: Erectile dysfunction (ED), Antidepressant-induced sexual dysfunction, Low libido, Sexual dysfunction.
  • The closest evidence on file: Zinc is rated "Possibly Ineffective" for Sexual dysfunction (Natural Medicines).
  • Also on file: Maca is rated "Insufficient Reliable Evidence To Rate" for Antidepressant-induced sexual dysfunction.
  • Also on file: Horny Goat Weed is rated "Insufficient Reliable Evidence To Rate" for Sexual dysfunction, Erectile dysfunction (ED).

The evidence for Hard-AF's ingredients is limited. Vitamin B3 is rated Likely Effective for pellagra (a nutritional deficiency) and Possibly Effective for certain kinds of high cholesterol.

Zinc is Effective for zinc deficiency and Likely Effective for Wilson disease, and Possibly Effective for acne and age-related eye disease. Eurycoma longifolia extract is Possibly Effective for sexual desire.

For the other ingredients—maca powder, yohimbine HCl, cassia cinnamon, Korean Red Ginseng, Byroviron, Kaempferia parviflora, horny goat weed, and Capsorb—the evidence we hold is Insufficient Reliable Evidence To Rate them for their intended uses, or we have no data on file. This means the research doesn't yet establish whether they work for what the product claims.

The evidence, ingredient by ingredient Niacin Zinc Maca Yohimbe Cassia Cinnamon Eurycoma Longifolia Horny Goat Weed

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 7 of the 7 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 7 of 7.
  • General safety write-ups exist for 7 of 7.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Yohimbine HCl carries serious safety concerns. It can raise blood pressure and heart rate significantly and cause anxiety, tremors, agitation, and in rare cases, heart rhythm problems or hypertensive crisis.

The facts note that supplement potency is unpredictable. Vitamin B3 is well tolerated at food amounts and prescription doses under medical supervision, but high supplement doses can cause flushing, liver damage, and gastrointestinal upset.

Cassia cinnamon in food amounts is generally safe, but large supplement doses may cause liver harm over time due to its coumarin content. Zinc is well tolerated below 40 mg daily; higher doses may cause nausea, diarrhea, and risk copper deficiency.

Maca is generally well tolerated as a food but lacks long-term safety studies in supplement form. Horny goat weed has limited safety data; short-term use may be tolerated but quality varies between products.

Korean Red Ginseng, Byroviron, Kaempferia parviflora, and Capsorb—we have no adverse-effect data on file for these.

Side effects, ingredient by ingredient Niacin Zinc Maca Yohimbe Cassia Cinnamon Eurycoma Longifolia Horny Goat Weed

Meds to double-check

Major interaction found
Known Interaction Concern · database check
Major identified

At least one ingredient has a documented Major-severity interaction. Check your medications for a personalized result.

Why this rating?
  • 6 of the 7 matched ingredients can interact with medications — Horny Goat Weed, Yohimbe, Niacin, Zinc, Cassia Cinnamon, among others.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; diabetes medications.
  • For scale: 1,417 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Before taking Hard-AF, check with your doctor or pharmacist if you take MAOIs (Major severity), blood pressure medications, antidepressants (especially tricyclics), stimulants, diabetes drugs, blood thinners (anticoagulants), antibiotics (quinolones, tetracyclines, cephalexin), cholesterol medications (statins), gout drugs, liver-toxic medications, or HIV medications. Yohimbine HCl's interaction with MAOIs is the most serious; combining them can cause dangerous blood pressure and heart effects.

The product affects how your body metabolizes numerous drugs through multiple enzyme systems.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFormula with limited ingredient disclosure with graded evidence leaning against its stated purpose. Major medication interactions have been identified, and safety information is well characterized.

Hard-AF is a multi-ingredient supplement with limited evidence that its active ingredients work for claimed effects and carries significant drug interactions, especially with blood pressure medications, antidepressants, and antibiotics. Anyone on prescription medications—particularly MAOIs, blood pressure drugs, diabetes medications, or antibiotics—should check their exact drugs with the interaction tool on this page before taking it.

Yohimbine HCl's unpredictable potency and serious cardiovascular effects add extra caution. Talk with your doctor or pharmacist about whether Hard-AF is right for you and safe alongside your own medications.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 7 of 11 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jun 24, 2020.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Hard-AF, straight from the product label.

Brand Steel
Net contents 20 Capsule(s)
Market status On market
Date entered into DSLD Jun 24, 2020
DSLD ID 228722
Product type Other Combinations
Supplement form Capsule
Dietary claims / uses All Other
Intended target group(s) Adult Male (18-50 Years)
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Hard-AF by Steel, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
2 Capsule(s)
Maximum serving Sizes:
2 Capsule(s)
Servings per container
10
IngredientAmount% DV
Maca powder0 NP--
Yohimbine HCl0 NP--
Vitamin B350 mg312%
Cinnamomum cassia0 NP--
Zinc11 mg100%
Korean Red Ginseng0 NP--
Eurycoma longifolia extract0 NP--
Hard-AF Vertical Blend1.01 Gram(s)--
Byroviron0 NP--
Kaempferia parviflora0 NP--
Epimedium brevicornum0 NP--
Capsorb0 NP--

Other ingredients: Gelatin, Magnesium Stearate, Silicon Dioxide

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
General Statements

Forged in steel, backed by science.

Seals/Symbols

Made in the U.S.A.

GMP certified Good manufacturing practice Quality product

Formulation

Erection formula

FDA Statement of Identity

Dietary supplement

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Hard-AF by Steel label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Hard-AF label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Hard-AF by Steel

These are the 11 active ingredients this product is made of. Select any to open its full monograph.

Serving size2 Capsule(s) Dosage formCapsule Servings per container10 Amounts shown are per serving.

Most supplement products combine several ingredients, and a medication can interact with the product through any one of them. Each ingredient below shows whether it has known drug interactions.

Vitamin B3

Interacts with
727 drugs
50 mg per serving Form: Niacin

Niacin (vitamin B3) is an essential nutrient your body needs for energy and metabolism, and deficiency is uncommon in most developed countries. Prescr...

Vitamin B3 monograph & interactions

Zinc

Interacts with
67 drugs
11 mg per serving Form: Zinc Orotate

Zinc is an essential mineral that your body needs for immune function, wound healing, taste, and smell. Most people get enough from food, but suppleme...

Zinc monograph & interactions

Hard-AF Vertical Blend

1.01 Gram(s) per serving

Other (inactive) ingredients: Gelatin, Magnesium Stearate, Silicon Dioxide. These complete the product’s ingredient list but are not active constituents.

Interaction report

Hard-AF by Steel Drug Interactions

Want to check YOUR meds against Hard-AF?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
1,416Drugs
9 Major 1,396 Moderate 11 Minor

Ingredients driving the most interactions

Yohimbine HCl 1,125
Epimedium brevicornum 963
Vitamin B3 727
Cinnamomum cassia 442
Eurycoma longifolia extract 248

Individual Drug Interactions

The ingredients in Hard-AF interact with 1,416 drugs. Click any drug to see the details.

6 of the 11 ingredients in Hard-AF interact with drugs. Each result below shows which ingredient is responsible. Yohimbine HCl Epimedium brevicornum Vitamin B3 Cinnamomum cassia Eurycoma longifolia extract Zinc

Each ingredient & the kinds of drugs it affects

For each ingredient in Hard-AF with known interactions, here are the types of medications they can affect. Open any type for the detail — or search your exact drug in the checker above.

Yohimbine HCl13 drug types · 1,125 drugs

Monoamine Oxidase Inhibitors (Maois)

Concomitant use of MAOIs with yohimbe can result in additive effects.
Yohimbine, a constituent of yohimbe, has MAO inhibitory effects. At high doses, yohimbine is a non-selective inhibitor of MAO.

Likelihood Likely Evidence D
Antihypertensive Drugs

Theoretically, yohimbe might reduce the effects of antihypertensive drugs.
Yohimbine, a constituent of yohimbe, is an alpha-2 adrenoceptor antagonist and has been reported to increase blood pressure in clinical research. Theoretically, concomitant use of yohimbe and antihypertensive drugs can interfere with blood pressure control.

Likelihood Probable Evidence D
Clonidine (Catapres)

Theoretically, yohimbe might precipitate clonidine withdrawal.
Chronic clonidine use can downregulate alpha-2 adrenoreceptors. Animal research and one human case report suggest that concomitant administration of yohimbine, an alpha-2 adrenoceptor antagonist, may precipitate clonidine withdrawal and lead to sympathomimetic toxicity, including hypertensive crisis.

Likelihood Possible Evidence D
Cytochrome P450 2D6 (Cyp2D6) Inhibitors

CYP2D6 inhibitors may increase the levels and adverse effects of yohimbine, a constituent of yohimbe.
In vitro and clinical research shows that the yohimbe bark constituent, yohimbine, is metabolized by CYP2D6 isoenzymes. Paroxetine, a cytochrome P450 (CYP) 2D6 inhibitor, increases the maximum serum concentration of yohimbine and reduces the clearance of yohimbine compared to yohimbine alone in patients who are extensive CYP2D6 metabolizers..

Likelihood Probable Evidence B
Cytochrome P450 2D6 (Cyp2D6) Substrates

Theoretically, yohimbe might increase the levels and adverse effects of CYP2D6 substrates.
In vitro research suggests that yohimbine, a constituent of yohimbe bark, inhibits CYP2D6 enzyme activity.

Likelihood Possible Evidence D
Cytochrome P450 3A4 (Cyp3A4) Inhibitors

Theoretically, CYP3A4 inhibitors might increase the levels and adverse effects of yohimbine, a constituent of yohimbe bark.
In vitro and clinical research shows that the yohimbe bark constituent, yohimbine, is metabolized by CYP3A4 enzymes. Theoretically, drugs that inhibit CYP3A4 might increase the levels and adverse effects of yohimbine.

Likelihood Possible Evidence D
Paroxetine (Paxil)

Paroxetine decreases the clearance of yohimbine and may increase its effects.
Paroxetine, a cytochrome P450 (CYP) 2D6 inhibitor, increases the maximum serum concentration of yohimbine by about 350% and reduces the clearance of yohimbine by about 80% compared to yohimbine alone in patients who are extensive CYP2D6 metabolizers. No significant changes in pharmacokinetic parameters of yohimbine were observed with coadministration of paroxetine in patients who are poor CYP2D6 metabolizers.

Likelihood Probable Evidence B
Phenothiazines

Theoretically, using yohimbine with phenothiazines might have additive effects.
Yohimbine, a constituent of yohimbe, has alpha-2 adrenergic antagonist effects. Theoretically, combining it with phenothiazines can cause additive alpha-2 adrenergic antagonism.

Likelihood Possible Evidence D
Stimulant Drugs

Theoretically, taking yohimbe with stimulant drugs can have additive effects.
Yohimbine, a constituent of yohimbe, has sympathomimetic effects and increases blood pressure in a dose-dependent manner. Theoretically, taking yohimbe with stimulant drugs can have additive stimulant and hypertensive effects.

Likelihood Possible Evidence D
Tricyclic Antidepressants (Tcas)

Theoretically, taking yohimbe with TCAs can increase adverse effects.
A small clinical study in patients taking TCAs for at least 4 weeks shows that receiving doses of intravenous yohimbine 2.5-20 mg daily for up to 7 days precipitates severe anxiety, agitation, and tremor. The effects of yohimbe bark itself are unclear; oral yohimbe bark contains 0.6% to 1.38% yohimbine, but it is unclear how much is absorbed.

Likelihood Possible Evidence D
Anticoagulant/Antiplatelet Drugs

Theoretically, combining yohimbe bark with antiplatelet or anticoagulant drugs might have additive effects; however, this has not been reported in clinical research.
Research in healthy adults shows that taking yohimbine, a constituent of yohimbe bark, in doses of 8 mg or more, seems to inhibit platelet aggregation in vitro by binding to the alpha-2 adrenoceptor. The effects of yohimbe bark itself are unclear; yohimbe bark contains 0.6% to 1.38% yohimbine, but it is unclear how much is absorbed.

Likelihood Possible Evidence D
Cytochrome P450 1A2 (Cyp1A2) Substrates

Theoretically, yohimbe might decrease the levels and clinical effects of CYP1A2 substrates.
In vitro research shows that yohimbe extract induces CYP1A2 enzymes.

Likelihood Possible Evidence D
Cytochrome P450 3A4 (Cyp3A4) Substrates

Theoretically, yohimbe might decrease the levels and clinical effects of CYP3A4 substrates.
In vitro research shows that yohimbe extract induces CYP3A4 enzymes.

Likelihood Possible Evidence D
Yohimbine HCl full monograph & interactions

Epimedium brevicornum6 drug types · 963 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, horny goat weed might increase the risk of bleeding.
In vitro research and animal research shows that horny goat weed can inhibit platelet aggregation and thrombus formation. This effect has not been reported in humans.

Likelihood Possible Evidence D
Antihypertensive Drugs

Theoretically, horny goat weed might increase the risk of hypotension.
Laboratory research suggests that horny goat weed might have hypotensive effects. This effect has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 1A2 (Cyp1A2) Substrates

Theoretically, horny goat weed might increase the effects and side effects of CYP1A2 substrates.
In vitro, horny goat weed leaf extract inhibits CYP1A2. This effect has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2B6 (Cyp2B6) Substrates

Theoretically, horny goat weed might increase the effects and side effects of CYP2B6 substrates.
In vitro, horny goat weed leaf extract inhibits CYP2B6. This effect has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 3A4 (Cyp3A4) Substrates

Theoretically, horny goat weed might increase the effects and side effects of CYP3A4 substrates.
In vitro, horny goat weed extract inhibits CYP3A4 and suppresses CYP3A4 mRNA expression. This effect has not been reported in humans.

Likelihood Possible Evidence D
Estrogens

Theoretically, concomitant use of horny goat weed with estrogens might increase their therapeutic and adverse effects.
In vitro evidence suggests that horny goat weed has estrogenic activity. In clinical research, horny goat weed has been shown to increase blood levels of estrogen in some females.

Likelihood Possible Evidence D
Epimedium brevicornum full monograph & interactions

Vitamin B315 drug types · 727 drugs

Alcohol (Ethanol)

Concomitant use of alcohol and niacin might increase the risk of flushing and hepatotoxicity.
Alcohol can exacerbate the flushing and pruritus associated with niacin. Large doses of niacin might also exacerbate liver dysfunction associated with chronic alcohol use. A case report describes delirium and lactic acidosis in a patient taking niacin 3 grams daily who ingested 1 liter of wine. Advise patients to avoid large amounts of alcohol while taking niacin.

Likelihood Probable Evidence D
Allopurinol (Zyloprim)

Theoretically, niacin might antagonize the therapeutic effects of uricosurics such as allopurinol.
Large doses of niacin can reduce urinary excretion of uric acid, potentially resulting in hyperuricemia. Doses of uricosurics such as allopurinol might need to be increased to maintain control of gout in patients who start taking niacin. People who have frequent attacks of gout despite uricosuric therapy should avoid niacin.

Likelihood Probable Evidence C
Anticoagulant/Antiplatelet Drugs

Theoretically, niacin may have additive effects when used with anticoagulant or antiplatelet drugs.
Several cases of clotting factor synthesis deficiency and coagulopathy have been reported in patients taking sustained-release niacin. Also, thrombocytopenia has been reported in patients treated with niacin or niacin plus lovastatin.

Likelihood Possible Evidence D
Antidiabetes Drugs

Niacin can increase blood glucose levels and may diminish the effects of antidiabetes drugs.
Niacin impairs glucose tolerance in a dose-dependent manner, probably by causing or aggravating insulin resistance and increasing hepatic production of glucose. In diabetes patients, niacin 4.5 grams daily for 5 weeks can increase plasma glucose by an average of 16% and glycated hemoglobin (HbA1c) by 21%. However, lower doses of 1.5 grams daily or less appear to have minimal effects on blood glucose. In some patients, glucose levels increase when niacin is started, but then return to baseline when a stable dose is reached. Up to 35% of patients with diabetes may need adjustments in hypoglycemic therapy when niacin is added.

Likelihood Probable Evidence B
Antihypertensive Drugs

Theoretically, niacin may increase the risk of hypotension when used with antihypertensive drugs.
The vasodilating effects of niacin can cause hypotension. Furthermore, some clinical evidence suggests that a one-hour infusion of niacin can reduce systolic, diastolic, and mean blood pressure in hypertensive patients. This effect is not observed in normotensive patients.

Likelihood Possible Evidence B
Bile Acid Sequestrants

Bile acid sequestrants can bind niacin and decrease absorption. Separate administration by 4-6 hours to avoid an interaction.
In vitro studies show that colestipol (Colestid) binds about 98% of available niacin and cholestyramine (Questran) binds 10% to 30%.

Likelihood Possible Evidence D
Gemfibrozil (Lopid)

Theoretically, concomitant use of niacin and gemfibrozil might increase the risk of myopathy in some patients.
A case of myopathy from concomitant use of niacin and gemfibrozil has been reported. Niacin alone has also been associated with cases of myopathy. Using gemfibrozil with niacin might further increase the risk of developing myopathy.

Likelihood Possible Evidence D
Hepatotoxic Drugs

Theoretically, concomitant use of niacin and hepatotoxic drugs might increase the risk of hepatotoxicity.
Niacin has been associated with cases of liver toxicity, especially when used in pharmacologic doses. Sustained-release niacin preparations appear to be associated with a higher risk of hepatotoxicity than immediate-release niacin.

Likelihood Possible Evidence D
Hmg-Coa Reductase Inhibitors ("Statins")

Theoretically, concomitant use of niacin and statins might increase the risk of myopathy and rhabdomyolysis in some patients.
Some case reports have raised concerns that niacin might increase the risk of myopathy and rhabdomyolysis when combined with statins. However, a significantly increased risk of myopathy has not been demonstrated in clinical trials, including those using an FDA-approved combination of lovastatin and niacin (Advicor).

Likelihood Possible Evidence D
Probenecid (Benemid)

Theoretically, niacin might antagonize the therapeutic effects of uricosurics such as probenecid.
Large doses of niacin reduce urinary excretion of uric acid, potentially causing hyperuricemia. Doses of uricosurics such as probenecid might need to be increased to maintain control of gout in patients who start taking niacin. People who have frequent attacks of gout despite uricosuric therapy should avoid niacin.

Likelihood Probable Evidence C
Sulfinpyrazone (Anturane)

Theoretically, niacin might antagonize the therapeutic effects of uricosurics such as sulfinpyrazone.
Large doses of niacin reduce urinary excretion of uric acid, potentially causing hyperuricemia. Doses of uricosurics such as sulfinpyrazone might need to be increased to maintain control of gout in patients who start taking niacin. People who have frequent attacks of gout despite uricosuric therapy should avoid niacin.

Likelihood Probable Evidence C
Thyroid Hormone

Theoretically, niacin might antagonize the therapeutic effects of thyroid hormones.
Clinical research and case reports suggests that taking niacin can reduce serum levels of thyroxine-binding globulin by up to 25% and moderately reduce levels of thyroxine (T4). Patients taking thyroid hormone for hypothyroidism might need dose adjustments when using niacin.

Likelihood Probable Evidence D
Transdermal Nicotine (Nicoderm)

Theoretically, concomitant use of niacin and transdermal nicotine might increase the risk of flushing and dizziness.
Niacin and nicotine can both cause flushing and dizziness.

Likelihood Possible Evidence D
Warfarin (Coumadin)

There is limited evidence that niacin may increase the anticoagulant effects of warfarin.
In a case report, a patient on warfarin developed an elevated international normalized ratio (INR) of 3.9 after taking niacin for two weeks. The patient's INR was previously stable, ranging between 2 and 3 in recent months, and no other medication changes were identified. The elevated INR returned to therapeutic range within 4 days following the discontinuation of niacin.

Likelihood Possible Evidence D
Aspirin

Large doses of aspirin might alter the clearance of niacin.
Aspirin is often used with niacin to reduce niacin-induced flushing. Doses of 80-975 mg aspirin have been used, but 325 mg appears to be optimal. Aspirin also seems to reduce the clearance of niacin by competing for glycine conjugation. Taking aspirin 1 gram seems to reduce niacin clearance by 45%. This is probably a dose-related effect and not clinically significant with the more common aspirin dose of 325 mg.

Likelihood Likely Evidence B
Vitamin B3 full monograph & interactions

Cinnamomum cassia2 drug types · 442 drugs

Antidiabetes Drugs

Theoretically, cassia cinnamon may have additive effects with antidiabetes drugs.
Cassia cinnamon may lower blood glucose levels, and have additive effects in patients treated with antidiabetic agents. Dose adjustments to diabetes medications might be necessary.

Likelihood Possible Evidence B
Hepatotoxic Drugs

Theoretically, large doses of cassia cinnamon might cause additive effects when used with hepatotoxic drugs.
There is some concern that ingesting large amounts of cassia cinnamon for an extended duration might cause hepatotoxicity in some people. Cassia cinnamon contains coumarin, which can cause hepatotoxicity in animal models. In humans, very high doses of coumarin from 50-7000 mg/day can result in hepatotoxicity that resolves when coumarin use is discontinued. Lower amounts might also cause liver problems in sensitive people, such as those with liver disease or those taking potentially hepatotoxic agents.

Likelihood Possible Evidence D
Cinnamomum cassia full monograph & interactions

Eurycoma longifolia extract5 drug types · 248 drugs

Propranolol (Inderal)

Eurycoma longifolia can reduce the levels and clinical effects of propranolol.
A small clinical study in healthy persons shows that taking a single dose of a water-based Eurycoma longifolia extract 200 mg, in combination with a single dose of propranolol 80 mg, reduces the propranolol area under the curve (AUC) by 29%, reduces the peak concentration by 42%, and increases time to peak concentration by 86% when compared with control. Since the elimination half-life of propranolol did not change, it seems that Eurycoma longifolia alters the kinetics of propranolol by decreasing its absorption in the gut, and not by altering its metabolism. It is not known if separating administration will prevent this interaction.

Likelihood Probable Evidence A
Cytochrome P450 1A2 (Cyp1A2) Substrates

Theoretically, Eurycoma longifolia might increase levels CYP1A2 substrates.
In vitro research suggests that methanolic Eurycoma longifolia root extract weakly inhibits CYP1A2 enzymes. This effect has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2A6 (Cyp2A6) Substrates

Theoretically, Eurycoma longifolia might increase levels of CYP2A6 substrates.
In vitro research suggests that methanolic Eurycoma longifolia root extract weakly inhibits CYP2A6 enzymes. This effect has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2C19 (Cyp2C19) Substrates

Theoretically, Eurycoma longifolia might increase levels of CYP2C19 substrates.
In vitro research suggests that methanolic Eurycoma longifolia root extract weakly inhibits CYP2C19 enzymes. This effect has not been reported in humans.

Likelihood Possible Evidence D
Testosterone

Theoretically, Eurycoma longifolia may further increase levels of testosterone.
A clinical study in aging males with testosterone levels below 300 ng/dL shows that taking a specific water extract of Eurycoma longifolia roots (Physta; Biotropics Malaysia) 100-200 mg daily with breakfast for 12 weeks increases total testosterone levels by 8% to 11% when compared with placebo. It is unclear whether this increase would occur in individuals with normal testosterone levels.

Likelihood Possible Evidence D
Eurycoma longifolia extract full monograph & interactions

Zinc10 drug types · 67 drugs

Bictegravir/Emtricitabine/Tenofovir Alafenamide (Biktarvy)

Theoretically, zinc might decrease levels of bictegravir/emtricitabine/tenofovir alafenamide by reducing its absorption.
Advise patients that bictegravir/emtricitabine/tenofovir alafenamide should be taken at least 2 hours before or 6 hours after zinc containing products.

Likelihood Probable Evidence D
Cephalexin (Keflex)

Zinc might decrease cephalexin levels by chelating with cephalexin in the gut and preventing its absorption.
A pharmacokinetic study shows that zinc sulfate 250 mg taken concomitantly with cephalexin 500 mg decreases peak levels of cephalexin by 31% and reduces the exposure to cephalexin by 27%. Also, taking zinc sulfate 3 hours before cephalexin decreases peak levels of cephalexin by 11% and reduces the exposure to cephalexin by 18%. By decreasing cephalexin levels, zinc might increase the risk of treatment failure. This effect does not occur when zinc is taken 3 hours after the cephalexin dose. To avoid an interaction, advise patients take zinc sulfate 3 hours after taking cephalexin.

Likelihood Probable Evidence B
Cisplatin (Platinol-Aq)

Theoretically, zinc might interfere with the therapeutic effects of cisplatin.
Animal research suggests that zinc stimulates tumor cell production of the protein metallothionein, which binds and inactivates cisplatin. It is not known whether zinc supplements or high dietary zinc intake can cause clinically significant interference with cisplatin therapy. Cisplatin might also increase zinc excretion.

Likelihood Possible Evidence D
Integrase Inhibitors

Theoretically, taking zinc along with integrase inhibitors might decrease the levels and clinical effects of these drugs.
Zinc is a divalent cation. Pharmacokinetic studies have shown that other divalent cations such as calcium and iron can decrease blood levels of the integrase inhibitor dolutegravir through chelation.

Likelihood Possible Evidence D
Penicillamine (Cuprimine, Depen)

Zinc might reduce the levels and clinical effects of penicillamine.
By forming an insoluble complex with penicillamine, zinc interferes with penicillamine absorption and activity. Zinc supplements reduce the efficacy of low-dose penicillamine (0.5-1 gram/day), but do not seem to affect higher doses (1-2.75 gram/day), provided dosing times are separated. Advise patients to take zinc and penicillamine at least 2 hours apart.

Likelihood Probable Evidence B
Quinolone Antibiotics

Zinc can decrease the levels and clinical effects of quinolones antibiotics.
Quinolones form complexes with zinc in the gastrointestinal tract, reducing absorption of both the quinolone and zinc if taken at the same time. Advise patients to take these drugs at least 2 hours before, or 4-6 hours after, zinc supplements.

Likelihood Probable Evidence B
Ritonavir (Norvir)

Zinc modestly reduces levels of ritonavir.
Clinical research shows that zinc might reduce serum ritonavir levels by chelating with ritonavir in the gut and preventing its absorption. In patients with HIV, ritonavir is taken with atazanavir to prevent the metabolism and increase the effects of atazanavir. A pharmacokinetic study shows that, in patients being treated with atazanavir/ritonavir, co-administration of zinc sulfate (Solvazinc tablets) 125 mg as a single dose or as multiple daily doses for 2 weeks reduces plasma levels of ritonavir by about 16%. However, atazanavir levels still remains high enough to prevent HIV virus replication. Therefore, the decrease in ritonavir levels is not likely to be clinically significant.

Likelihood Probable Evidence B
Tetracycline Antibiotics

Zinc might reduce levels of tetracycline antibiotics.
Tetracyclines form complexes with zinc in the gastrointestinal tract, which can reduce absorption of both the tetracycline and zinc when taken at the same time. Taking zinc sulfate 200 mg with tetracycline reduces absorption of the antibiotic by 30% to 40%. Demeclocycline and minocycline cause a similar interaction. However, doxycycline does not seem to interact significantly with zinc. Advise patients to take tetracyclines at least 2 hours before, or 4-6 hours after, zinc supplements to avoid any interactions.

Likelihood Probable Evidence B
Amiloride (Midamor)

Amiloride can modestly reduce zinc excretion and increase zinc levels.
Clinical research shows that amiloride can reduce urinary zinc excretion, especially at doses of 10 mg per day or more. This zinc-sparing effect can help to counteract zinc losses caused by thiazide diuretics, but it is unlikely to cause zinc toxicity at usual amiloride doses. The other potassium-sparing diuretics, spironolactone (Aldactone) and triamterene (Dyrenium), do not seem to have a zinc-sparing effect.

Likelihood Probable Evidence B
Atazanavir (Reyataz)

Zinc modestly reduces levels of atazanavir, although this effect does not seem to be clinically significant.
Clinical research shows that zinc might decrease serum atazanavir levels by chelating with atazanavir in the gut and preventing its absorption. Although a single dose of zinc sulfate (Solvazinc tablets) 125 mg orally does not affect atazanavir concentrations in patients being treated with atazanavir/ritonavir, co-administration of zinc sulfate 125 mg daily for 2 weeks reduces plasma levels of atazanavir by about 22% in these patients. However, despite this decrease, atazanavir levels still remain at high enough concentrations for the prevention of HIV virus replication.

Likelihood Probable Evidence B
Zinc full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Hard-AF, from the product label.

Steel

Name
Steel Supplements
Pharmacist Counseling Corner

Hard-AF by Steel: Common Questions

Does Hard-AF by Steel interact with any medications?
Yes. Based on its ingredients, Hard-AF has a known interaction with 1,416 medications, including 9 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Hard-AF contains 11 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
Does Hard-AF work for sexual function?
The evidence we hold is Insufficient Reliable Evidence To Rate most of its ingredients for sexual effects. Eurycoma longifolia extract is rated Possibly Effective for sexual desire, but overall the product hasn't been rigorously studied. Talk with your doctor about realistic expectations.
Is it safe to take Hard-AF with blood pressure medication?
No—this product carries Moderate interactions with blood pressure drugs through yohimbine HCl, vitamin B3, and horny goat weed. All three can interfere with your medication's effectiveness or cause blood pressure to drop too low. Check with your doctor or pharmacist before combining them.
Can I take Hard-AF with antibiotics?
Zinc in Hard-AF can reduce absorption of several antibiotics, including quinolones, tetracyclines, and cephalexin. If you're taking an antibiotic, discuss the timing and whether Hard-AF is safe with your doctor or pharmacist—you may need to space them several hours apart.
What side effects might yohimbine HCl cause?
Common side effects include anxiety, agitation, tremors, increased heart rate, elevated blood pressure, sweating, diarrhea, headache, nausea, and flushing. Rare serious effects include hypertensive crisis and heart rhythm problems. The amount of yohimbine in supplements is unpredictable, which adds to the risk.
Can I take Hard-AF during pregnancy or while breastfeeding?
No. Yohimbine HCl is Possibly Unsafe in pregnancy and may affect the uterus. Maca, horny goat weed, and Eurycoma longifolia extract lack enough safety data for pregnancy and breastfeeding. Talk with your doctor or pharmacist before taking this product if you're pregnant or nursing.
Will Hard-AF interact with my antidepressant?
Possibly. Yohimbine HCl carries a Moderate interaction with tricyclic antidepressants and can cause severe anxiety, agitation, and tremor. It also has a Major interaction with MAOIs. If you take any antidepressant, check with your doctor or pharmacist before taking Hard-AF.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Hard-AF label
Go deeper

The Full Monographs Behind Hard-AF’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Niacin

Interacts with 727 drugs

Niacin (vitamin B3) is an essential nutrient your body needs for energy and metabolism, and deficiency is uncommon in most developed countries. Prescription-strength niacin has been used to...

Read the full Niacin monograph → Herb & supplement monograph

Zinc

Interacts with 67 drugs

Zinc is an essential mineral that your body needs for immune function, wound healing, taste, and smell. Most people get enough from food, but supplements can help correct or prevent a defici...

Read the full Zinc monograph → Herb & supplement monograph

Maca

Maca is a nutrient-rich Andean root often used for energy, libido, and menopause symptoms. Early studies suggest it may modestly help sexual desire and some menopause symptoms, but the evide...

Read the full Maca monograph → Herb & supplement monograph

Yohimbe

Interacts with 1,125 drugs

Yohimbe is a West African tree bark that contains yohimbine, a compound mainly promoted for erectile dysfunction and as an aphrodisiac. A prescription form of yohimbine has some evidence for...

Read the full Yohimbe monograph → Herb & supplement monograph

Cassia Cinnamon

Interacts with 442 drugs

Cassia cinnamon is the common, inexpensive cinnamon used in cooking, and it is also taken as a supplement, most often for blood sugar support. The evidence for its health benefits is mixed a...

Read the full Cassia Cinnamon monograph → Herb & supplement monograph

Eurycoma Longifolia

Interacts with 248 drugs

Eurycoma longifolia (tongkat ali) is a Southeast Asian herb most popular for supporting testosterone, libido, and male fertility, with some small human studies suggesting possible benefits....

Read the full Eurycoma Longifolia monograph → Herb & supplement monograph

Horny Goat Weed

Interacts with 963 drugs

Horny goat weed (Epimedium) is a traditional Chinese herb most often marketed for low libido and erectile problems, but solid human evidence for these uses is lacking. While short-term use s...

Read the full Horny Goat Weed monograph →
Sources

Sources & How We Checked

Hard-AF's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 256 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Maca 1 reference
  1. Valerio, L. G., Jr. and Gonzales, G. F. Toxicological aspects of the South American herbs cat's claw (Uncaria tomentosa) and Maca (Lepidium meyenii) : a critical synopsis. Toxicol.Rev 2005;24(1):11-35. PubMed

See these in context on the Maca monograph →

Yohimbe 66 references
  1. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
  2. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  3. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  4. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  5. Milman N, Scheibel J, Jessen O. Lysine prophylaxis in recurrent herpes simplex labialis: a double-blind, controlled crossover study. Acta Derm Venereol 1980;60:85-7.
  6. Teloken C, Rhoden EL, Sogari P, et al. Therapeutic effects of high dose yohimbine hydrochloride on organic erectile dysfunction. J Urol 1998;159:122-4. PubMed
  7. Jacobsen FM. Fluoxetine-induced sexual dysfunction and an open trial of yohimbine. J Clin Psychiatry 1992;53:119-22.
  8. Hollander E, McCarley A. Yohimbine treatment of sexual side effects induced by serotonin reuptake blockers. J Clin Psychiatry 1992;53:207-9.
  9. Sandler B, Aronson P. Yohimbine-induced cutaneous drug eruption, progressive renal failure, and lupus-like syndrome. Urol 1993;41:343-5. PubMed
  10. Kearney T, Tu N, Haller C. Adverse drug events associated with yohimbine-containing products: a retrospective review of the California Poison Control System reported cases. Ann Pharmacother 2010;44:1022-9. PubMed
  11. VandenBrink, B. M., Foti, R. S., Rock, D. A., Wienkers, L. C., and Wahlstrom, J. L. Prediction of CYP2D6 drug interactions from in vitro data: evidence for substrate-dependent inhibition. Drug Metab Dispos. 2012;40(1):47-53. PubMed
  12. Abebe, W. An overview of herbal supplement utilization with particular emphasis on possible interactions with dental drugs and oral manifestations. J Dent.Hyg. 2003;77(1):37-46.
  13. Mustonen, P., Savola, J., and Lassila, R. Atipamezole, an imidazoline-type alpha(2)-adrenoceptor inhibitor, binds to human platelets and inhibits their adrenaline-induced aggregation more effectively than yohimbine. Thromb.Res 8-1-2000;99(3):231-237.
  14. Cameron, O. G., Zubieta, J. K., Grunhaus, L., and Minoshima, S. Effects of yohimbine on cerebral blood flow, symptoms, and physiological functions in humans. Psychosom.Med 2000;62(4):549-559. PubMed
  15. Bowes, M. P., Peters, R. H., Kernan, W. J., Jr., and Hopper, D. L. Effects of yohimbine and idazoxan on motor behaviors in male rats. Pharmacol.Biochem.Behav. 1992;41(4):707-713.
  16. Bagheri, H., Schmitt, L., Berlan, M., and Montastruc, J. L. Effect of 3 weeks treatment with yohimbine on salivary secretion in healthy volunteers and in depressed patients treated with tricyclic antidepressants. Br J Clin Pharmacol 1992;34(6):555-558. PubMed
  17. Bagheri, H., Bompart, G., Girolami, J. P., Montastruc, J. L., and Montastruc, P. Is yohimbine-induced increase in salivary secretion a kinin-dependent mechanism? Fundam.Clin Pharmacol 1992;6(1):17-20. PubMed
  18. Swann, A. C., Birnbaum, D., Jagar, A. A., Dougherty, D. M., and Moeller, F. G. Acute yohimbine increases laboratory-measured impulsivity in normal subjects. Biol.Psychiatry 5-15-2005;57(10):1209-1211. PubMed
  19. Adeniyi, A. A., Brindley, G. S., Pryor, J. P., and Ralph, D. J. Yohimbine in the treatment of orgasmic dysfunction. Asian J Androl 2007;9(3):403-407. PubMed
  20. Murburg, M. M., Villacres, E. C., Ko, G. N., and Veith, R. C. Effects of yohimbine on human sympathetic nervous system function. J Clin Endocrinol.Metab 1991;73(4):861-865. PubMed
  21. Giampreti, A., Lonati, D., Locatelli, C., Rocchi, L., and Campailla, M. T. Acute neurotoxicity after yohimbine ingestion by a body builder. Clin Toxicol.(Phila) 2009;47(8):827-829. PubMed
  22. Bloomer, R. J., Canale, R. E., Blankenship, M. M., Hammond, K. G., Fisher-Wellman, K. H., and Schilling, B. K. Effect of the dietary supplement Meltdown on catecholamine secretion, markers of lipolysis, and metabolic rate in men and women: a randomized,
  23. Myers, A. and Barrueto, F., Jr. Refractory priapism associated with ingestion of yohimbe extract. J Med Toxicol. 2009;5(4):223-225.
  24. Berlin, I., Crespo-Laumonnier, B., Cournot, A., Landault, C., Aubin, F., Legrand, J. C., and Puech, A. J. The alpha 2-adrenergic receptor antagonist yohimbine inhibits epinephrine-induced platelet aggregation in healthy subjects. Clin Pharmacol.Ther. 199
  25. Swann, A. C. Mechanisms of impulsivity in bipolar disorder and related illness. Epidemiol.Psichiatr.Soc. 2010;19(2):120-130.
  26. Shibao, C., Okamoto, L. E., Gamboa, A., Yu, C., Diedrich, A., Raj, S. R., Robertson, D., and Biaggioni, I. Comparative efficacy of yohimbine against pyridostigmine for the treatment of orthostatic hypotension in autonomic failure. Hypertension 2010;56(5) PubMed
  27. Soeter, M. and Kindt, M. Stimulation of the noradrenergic system during memory formation impairs extinction learning but not the disruption of reconsolidation. Neuropsychopharmacology 2012;37(5):1204-1215. PubMed
  28. Cimolai, N. and Cimolai, T. Yohimbine use for physical enhancement and its potential toxicity. J Diet.Suppl 2011;8(4):346-354. PubMed
  29. Bagheri, H., Berlan, M., Montastruc, J. L., and Montastruc, P. Yohimbine and lacrimal secretion. Br J Clin Pharmacol. 1990;30(1):151-152.
  30. Landis, E. and Shore, E. Yohimbine-induced bronchospasm. Chest 1989;96(6):1424. PubMed
  31. Susset, J. G., Tessier, C. D., Wincze, J., Bansal, S., Malhotra, C., and Schwacha, M. G. Effect of yohimbine hydrochloride on erectile impotence: a double-blind study. J Urol. 1989;141(6):1360-1363. PubMed
  32. Chatelut, E., Rispail, Y., Berlan, M., and Montastruc, J. L. Yohimbine increases human salivary secretion. Br.J Clin Pharmacol. 1989;28(3):366-368. PubMed
  33. Montastruc, P., Berlan, M., and Montastruc, J. L. Effects of yohimbine on submaxillary salivation in dogs. Br J Pharmacol 1989;98(1):101-104. PubMed
  34. Charney, D. S., Price, L. H., and Heninger, G. R. Desipramine-yohimbine combination treatment of refractory depression. Implications for the beta-adrenergic receptor hypothesis of antidepressant action. Arch.Gen.Psychiatry 1986;43(12):1155-1161. PubMed
  35. Braddock, L., Cowen, P. J., Elliott, J. M., Fraser, S., and Stump, K. Binding of yohimbine and imipramine to platelets in depressive illness. Psychol.Med 1986;16(4):765-773. PubMed
  36. Bolme, P., Corrodi, H., Fuxe, K., Hokfelt, T., Lidbrink, P., and Goldstein, M. Possible involvement of central adrenaline neurons in vasomotor and respiratory control. Studies with clonidine and its interactions with piperoxane and yohimbine. Eur J Pharm PubMed
  37. Charney, D. S., Heninger, G. R., and Sternberg, D. E. Assessment of alpha 2 adrenergic autoreceptor function in humans: effects of oral yohimbine. Life Sci 6-7-1982;30(23):2033-2041.
  38. Boon, N. A., Elliott, J. M., Grahame-Smith, D. G., John-Green, T., and Stump, K. A comparison of alpha 2-adrenoreceptor binding characteristics of intact human platelets identified by [3H]-yohimbine and [3H]- dihydroergocryptine. J Auton.Pharmacol 1983;3
  39. Andrejak, M., Ward, M., and Schmitt, H. Cardiovascular effects of yohimbine in anaesthetized dogs. Eur.J Pharmacol 10-28-1983;94(3-4):219-228. PubMed
  40. Brodde, O. E., Anlauf, M., Arroyo, J., Wagner, R., Weber, F., and Buck, K. D. Hypersensitivity of adrenergic receptors and blood-pressure response to oral yohimbine in orthostatic hypotension. N.Engl.J Med 4-28-1983;308(17):1033-1034. PubMed
  41. Charney, D. S., Heninger, G. R., and Redmond, D. E., Jr. Yohimbine induced anxiety and increased noradrenergic function in humans: effects of diazepam and clonidine. Life Sci. 7-4-1983;33(1):19-29. PubMed
  42. Knoll, L. D., Benson, R. C., Jr., Bilhartz, D. L., Minich, P. J., and Furlow, W. L. A randomized crossover study using yohimbine and isoxsuprine versus pentoxifylline in the management of vasculogenic impotence. J Urol. 1996;155(1):144-146. DOI
  43. Betz, J. M., White, K. D., and der Marderosian, A. H. Gas chromatographic determination of yohimbine in commercial yohimbe products. J AOAC Int 1995;78(5):1189-1194. DOI
  44. Bagheri, H., Chale, J. J., Guyen, L. N., Tran, M. A., Berlan, M., and Montastruc, J. L. Evidence for activation of both adrenergic and cholinergic nervous pathways by yohimbine, an alpha 2-adrenoceptor antagonist. Fundam.Clin Pharmacol 1995;9(3):248-254.
  45. Kennedy, S. H., Gnam, W., Ralevski, E., and Brown, G. M. Melatonin responses to clonidine and yohimbine challenges. J Psychiatry Neurosci. 1995;20(4):297-304.
  46. Musso, N. R., Vergassola, C., Pende, A., and Lotti, G. Yohimbine effects on blood pressure and plasma catecholamines in human hypertension. Am J Hypertens. 1995;8(6):565-571. PubMed
  47. Morgan, C. A., III, Southwick, S. M., Grillon, C., Davis, M., Krystal, J. H., and Charney, D. S. Yohimbine-facilitated acoustic startle reflex in humans. Psychopharmacology (Berl) 1993;110(3):342-346. PubMed
  48. Adler, L. E., Hoffer, L., Nagamoto, H. T., Waldo, M. C., Kisley, M. A., and Giffith, J. M. Yohimbine impairs P50 auditory sensory gating in normal subjects. Neuropsychopharmacology 1994;10(4):249-257. PubMed
  49. Biaggioni, I., Robertson, R. M., and Robertson, D. Manipulation of norepinephrine metabolism with yohimbine in the treatment of autonomic failure. J Clin Pharmacol. 1994;34(5):418-423. PubMed
  50. Kenney, W. L., Zappe, D. H., Tankersley, C. G., and Derr, J. A. Effect of systemic yohimbine on the control of skin blood flow during local heating and dynamic exercise. Am J Physiol 1994;266(2 Pt 2):H371-H376. PubMed
  51. Friesen, K., Palatnick, W., and Tenenbein, M. Benign course after massive ingestion of yohimbine. J Emerg.Med 1993;11(3):287-288. PubMed
  52. Bierer, L. M., Aisen, P. S., Davidson, M., Ryan, T. M., Stern, R. G., Schmeidler, J., and Davis, K. L. A pilot study of oral physostigmine plus yohimbine in patients with Alzheimer disease. Alzheimer Dis.Assoc.Disord. 1993;7(2):98-104. PubMed
  53. Mann, K., Klingler, T., Noe, S., Roschke, J., Muller, S., and Benkert, O. Effects of yohimbine on sexual experiences and nocturnal penile tumescence and rigidity in erectile dysfunction. Arch.Sex Behav. 1996;25(1):1-16. PubMed
  54. Rowland, D. L., Kallan, K., and Slob, A. K. Yohimbine, erectile capacity, and sexual response in men. Arch Sex Behav 1997;26(1):49-62.
  55. Bremner, J. D., Innis, R. B., Ng, C. K., Staib, L. H., Salomon, R. M., Bronen, R. A., Duncan, J., Southwick, S. M., Krystal, J. H., Rich, D., Zubal, G., Dey, H., Soufer, R., and Charney, D. S. Positron emission tomography measurement of cerebral metaboli
  56. Riley AJ, Goodman R, Kellett JM, and et al. Double blind trial of yohimbine hydrochloride in the treatment of erection inadequacy. Sexual Marital Ther 1989;4(1):17-26. DOI
  57. Cohen PA, Wang YH, Maller G, DeSouza R, Khan IA. Pharmaceutical quantities of yohimbine found in dietary supplements in the USA. Drug Test Anal. 2015 Sep 22. PubMed
  58. Ruck B, Shih RD, Marcus SM. Hypertensive crisis from herbal treatment of impotence. Am J Emerg Med. 1999;17:317-318. PubMed
  59. Wylie KR. Yohimbine and sinusitis. Br J Psychiatry. 1996;169(3):384-5. PubMed
  60. Le Corre P, Parmer RJ, Kailasam MT, et al. Human sympathetic activation by alpha2-adrenergic blockade with yohimbine: Bimodal, epistatic influence of cytochrome P450-mediated drug metabolism. Clin Pharmacol Ther. 2004;76(2):139-53.
  61. Mueller-Schoell A, Michelet R, Weinelt F, Kloft C, Mikus G. CYP2D6 phenotype explains reported yohimbine concentrations in four severe acute intoxications. Arch Toxicol. 2021. PubMed
  62. Bharucha AE, Skaar T, Andrews CN, et al Relationship of cytochrome P450 pharmacogenetics to the effects of yohimbine on gastrointestinal transit and catecholamines in healthy subjects. Neurogastroenterol Motil. 2008;20(8):891-9. PubMed
  63. Schmauss M, Laakmann G, Dieterle D. Effects of alpha 2-receptor blockade in addition to tricyclic antidepressants in therapy-resistant depression. J Clin Psychopharmacol. 1988;8(2):108-11.
  64. Haron MH, Dale O, Martin K, et al. Evaluation of the Herb-Drug Interaction Potential of Commonly Used Botanicals on the US Market with Regard to PXR- and AhR-Mediated Influences on CYP3A4 and CYP1A2. J Diet Suppl 2022. PubMed
  65. Hodapp B, Haggerty A, Feldman R, Timpe J. Intracranial hemorrhage after a single dose of Yohimbine in a chronic user of clonidine. Am J Emerg Med 2022;62:145. PubMed
  66. Vay M, Meyer MJ, Blank A, et al. Oral yohimbine as a new probe drug to predict CYP2D6 activity: results of a fixed-sequence phase I trial. Clin Pharmacokinet. 2020;59(7):927-939. PubMed

See these in context on the Yohimbe monograph →

Niacin 66 references
  1. Garg R, Malinow MR, Pettinger M, et al. Niacin treatment increases plasma homocysteine levels. Am Heart J 1999;138:1082-7.
  2. Anon. Inositol hexaniacinate. Altern Med Rev 1998;3:222-3.
  3. Knodel LC, Talbert RL. Adverse effects of hypolipidaemic drugs. Med Toxicol 1987;2:10-32. PubMed
  4. Guyton JR, Blazing MA, Hagar J, et al. Extended-release niacin vs gemfibrozil for the treatment of low levels of high-density lipoprotein cholesterol. Niaspan-Gemfibrozil Study Group. Arch Intern Med 2000;160:1177-84. PubMed
  5. Gibbons LW, Gonzalez V, Gordon N, Grundy S. The prevalence of side effects with regular and sustained-release nicotinic acid. Am J Med 1995;99:378-85. PubMed
  6. Whelan AM, Price SO, Fowler SF, Hainer BL. The effect of aspirin on niacin-induced cutaneous reactions. J Fam Pract 1992;34:165-8.
  7. Jungnickel PW, Maloley PA, Vander Tuin EL, et al. Effect of two aspirin pretreatment regimens on niacin-induced cutaneous reactions. J Gen Intern Med 1997;12:591-6. PubMed
  8. Capuzzi DM, Guyton JR, Morgan JM, et al. Efficacy and safety of an extended-release niacin (Niaspan): a long-term study. Am J Cardiol 1998;82:74-81;disc. 85U-6U. PubMed
  9. Gray DR, Morgan T, Chretien SD, Kashyap ML. Efficacy and safety of controlled-release niacin in dyslipoproteinemic veterans. Ann Intern Med 1994;121:252-8. PubMed
  10. McKenney JM, Proctor JD, Harris S, Chinchili VM. A comparison of the efficacy and toxic effects of sustained- vs immediate-release niacin in hypercholesterolemic patients. JAMA 1994;271:672-7. DOI
  11. Knopp RH, Alagona P, Davidson M, et al. Equivalent efficacy of a time-release form of niacin (Niaspan) given once-a-night versus plain niacin in the management of hyperlipidemia. Metabolism 1998;47:1097-104. PubMed
  12. Knopp RH. Clinical profiles of plain versus sustained-release niacin (Niaspan) and the physiologic rationale for nighttime dosing. Am J Cardiol 1998;82:24U-28U;discussion 39U-41U. PubMed
  13. Garg A, Grundy SM. Nicotinic acid as therapy for dyslipidemia in non-insulin-dependent diabetes mellitus. JAMA 1990;264:723-6. DOI
  14. Leighton RF, Gordon NF, Small GS, et al. Dental and gingival pain as side effects of niacin therapy. Chest 1998;114:1472-4. PubMed
  15. American Society of Health-System Pharmacists. ASHP Therapeutic Position Statement on the safe use of niacin in the management of dyslipidemias. Am J Health Syst Pharm 1997;54:2815-9. DOI
  16. Vega GL, Grundy SM. Lipoprotein responses to treatment with lovastatin, gemfibrozil, and nicotinic acid in normolipidemic patients with hypoalphalipoproteinemia. Arch Intern Med 1994;154:73-82. DOI
  17. Guyton JR, Goldberg AC, Kreisberg RA, et al. Effectiveness of once-nightly dosing of extended-release niacin alone and in combination for hypercholesterolemia. Am J Cardiol 1998;82:737-43.
  18. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (2000). Washington, DC: National Academy Press, 2000. Available at: http://b
  19. Brown BG, Zhao XQ, Chait A, et al. Simvastatin and niacin, antioxidant vitamins, or the combination for the prevention of coronary disease. N Engl J Med 2001;345:1583-93. DOI
  20. Bays HE, Dujovne CA. Drug interactions of lipid-altering drugs. Drug Saf 1998;19:355-71. PubMed
  21. Rader JI, Calvert RJ, Hathcock JN. Hepatic toxicity of unmodified and time-release preparations of niacin. Am J Med 1992;92:77-81. PubMed
  22. Kahn SE, Beard JC, Schwartz MW, et al. Increased B-cell secretory capacity as mechanism for islet adaptation to nicotinic acid-induced insulin resistance. Diabetes 1989;38:562-8.
  23. Schwartz ML. Severe reversible hyperglycemia as a consequence of niacin therapy. Arch Int Med 1993;153:2050-2. DOI
  24. Raising HDL and Niacin Use. Pharmacist's Letter/Prescriber's Letter 2004;20(5):200504.
  25. McKenney J. New perspectives on the use of niacin in the treatment of lipid disorders. Arch Intern Med 2004;164:697-705. PubMed
  26. Reaven P, Witztum JL. Lovastatin, nicotinic acid and rhabdomyolysis (letter). Ann Int Med 1988;109:597-8. PubMed
  27. Ito MK. Advances in the understanding and management of dyslipidemia: using niacin-based therapies. Am J Health-Syst Pharm 2003;60(suppl 2):s15-21. PubMed
  28. Schwab RA, Bachhuber BH. Delirium and lactic acidosis caused by ethanol and niacin coingestion. Am J Emerg Med 1991;9:363-5. PubMed
  29. Product information: Niaspan. Kos Pharmaceuticals. Cranbury, NJ. 2005. Available at www.niaspan.com/professional/content/pdfs/productinfo.pdf. (Accessed 3 March 2006).
  30. Ding RW, Kolbe K, Merz B, et al. Pharmacokinetics of nicotinic acid-salicylic acid interaction. Clin Pharmacol Ther 1989;46:642-7. PubMed
  31. NIH News. NIH stops clinical trial on combination cholesterol treatment. May 26, 2011. http://www.nih.gov/news/health/may2011/nhlbi-26.htm. (Accessed 3 June 2011).
  32. Dearing BD, Lavie CJ, Lohmann TP, Genton E. Niacin-induced clotting factor synthesis deficiency with coagulopathy. Arch Intern Med. 1992;152(4):861-3. DOI
  33. O'Brien T, Silverberg JD, Nguyen TT. Nicotinic acid-induced toxicity associated with cytopenia and decreased levels of thyroxine-binding globulin. Mayo Clin Proc. 1992;67(5):465-8. PubMed
  34. Gadegbeku CA, Dhandayuthapani A, Shrayyef MZ, Egan BM. Hemodynamic effects of nicotinic acid infusion in normotensive and hypertensive subjects. Am J Hypertens. 2003;16(1):67-71. PubMed
  35. Garnett WR. Interactions with hydroxymethylglutaryl-coenzyme A reductase inhibitors. Am J Health Syst Pharm. 1995;52(15):1639-45. PubMed
  36. Litin SC, Anderson CF. Nicotinic acid-associated myopathy: a report of three cases. Am J Med. 1989;86(4):481-3. PubMed
  37. Dunn RT, Ford MA, Rindone JP, Kwiecinski FA. Low-Dose Aspirin and Ibuprofen Reduce the Cutaneous Reactions Following Niacin Administration. Am J Ther. 1995;2(7):478-480. PubMed
  38. Cashin-Hemphill L, Spencer CA, Nicoloff JT, et al. Alterations in serum thyroid hormonal indices with colestipol-niacin therapy. Ann Intern Med. 1987;107(3):324-9. PubMed
  39. Drinka PJ. Alterations in thyroid and hepatic function tests associated with preparations of sustained-release niacin. Mayo Clin Proc. 1992;67(12):1206. PubMed
  40. Shakir KM, Kroll S, Aprill BS, Drake AJ 3rd, Eisold JF. Nicotinic acid decreases serum thyroid hormone levels while maintaining a euthyroid state. Mayo Clin Proc. 1995;70(6):556-8. PubMed
  41. Etchason JA, Miller TD, Squires RW, et al. Niacin-induced hepatitis: a potential side effect with low-dose time-release niacin. Mayo Clin Proc. 1991;66(1):23-8. PubMed
  42. Henkin Y, Johnson KC, Segrest JP. Rechallenge with crystalline niacin after drug-induced hepatitis from sustained-release niacin. JAMA. 1990;264(2):241-3. DOI
  43. Henkin Y, Oberman A, Hurst DC, Segrest JP. Niacin revisited: clinical observations on an important but underutilized drug. Am J Med. 1991;91(3):239-46. PubMed
  44. Brown BG, Bardsley J, Poulin D, et al. Moderate dose, three-drug therapy with niacin, lovastatin, and colestipol to reduce low-density lipoprotein cholesterol <100 mg/dl in patients with hyperlipidemia and coronary artery disease. Am J Cardiol. 1997;80(2)
  45. Goldberg A, Alagona P Jr, Capuzzi DM, et al. Multiple-dose efficacy and safety of an extended-release form of niacin in the management of hyperlipidemia. Am J Cardiol. 2000;85(9):1100-5. PubMed
  46. Aronov DM, Keenan JM, Akhmedzhanov NM, et al. Clinical trial of wax-matrix sustained-release niacin in a Russian population with hypercholesterolemia. Arch Fam Med. 1996;5(10):567-75. PubMed
  47. Morgan JM, Capuzzi DM, Guyton JR, et al. Treatment Effect of Niaspan, a Controlled-release Niacin, in Patients With Hypercholesterolemia: A Placebo-controlled Trial. J Cardiovasc Pharmacol Ther. 1996;1(3):195-202. PubMed
  48. Andersson RG, Aberg G, Brattsand R, Ericsson E, Lundholm L. Studies on the mechanism of flush induced by nicotinic acid. Acta Pharmacol Toxicol (Copenh). 1977 Jul;41(1):1-10. PubMed
  49. Brown WV. Niacin for lipid disorders. Indications, effectiveness, and safety. Postgrad Med. 1995 Aug;98(2):185-9, 192-3. PubMed
  50. O'REILLY PO, CALLBECK MJ, HOFFER A. Sustained-release nicotinic acid (nicospan); effect on (1) cholesterol levels and (2) leukocytes. Can Med Assoc J. 1959;80(5):359-62.
  51. Gharavi AG, Diamond JA, Smith DA, Phillips RA. Niacin-induced myopathy. Am J Cardiol. 1994;74(8):841-2. PubMed
  52. Litin SC, Anderson CF. Nicotinic acid-associated myopathy: a report of three cases. Am J Med. 1989;86(4):481-3. PubMed
  53. Fraunfelder FW, Fraunfelder FT, Illingworth DR. Adverse ocular effects associated with niacin therapy. Br J Ophthalmol 1995;79:54-56. PubMed
  54. Ali EH, McJunkin B, Jubelirer S, Hood W. Niacin induced coagulopathy as a manifestation of occult liver injury. W V Med J. 2013 Jan-Feb;109(1):12-4
  55. Aramwit P, Srisawadwong R, Supasyndh O. Effectiveness and safety of extended-release nicotinic acid for reducing serum phosphorus in hemodialysis patients. J Nephrol. 2012 May-Jun;25(3):354-62. PubMed
  56. Bassan M. A case for immediate-release niacin. Heart Lung. 2012 Jan-Feb;41(1):95-8. PubMed
  57. Davidson MH, Rooney M, Pollock E, Drucker J, Choy Y. Effect of colesevelam and niacin on low-density lipoprotein cholesterol and glycemic control in subjects with dyslipidemia and impaired fasting glucose. J Clin Lipidol. 2013 Sep-Oct;7(5):423-32. PubMed
  58. Guyton JR, Fazio S, Adewale AJ, Jensen E, Tomassini JE, Shah A, Tershakovec AM. Effect of extended-release niacin on new-onset diabetes among hyperlipidemic patients treated with ezetimibe/simvastatin in a randomized controlled trial. Diabetes Care. 2012 PubMed
  59. Loebl T, Raskin S. A novel case report: acute manic psychotic episode after treatment with niacin. J Neuropsychiatry Clin Neurosci. 2013 Fall;25(4):E14. PubMed
  60. Teo KK, Goldstein LB, Chaitman BR, Grant S, Weintraub WS, Anderson DC, Sila CA, Cruz-Flores S, Padley RJ, Kostuk WJ, Boden WE; AIM-HIGH Investigators. Extended-release niacin therapy and risk of ischemic stroke in patients with cardiovascular disease: the
  61. Goldie C, Taylor AJ, Nguyen P, McCoy C, Zhao XQ, Preiss D. Niacin therapy and the risk of new-onset diabetes: a meta-analysis of randomized controlled trials. Heart. 2016 Feb;102(3):198-203.
  62. Schandelmaier S, Briel M, Saccilotto R, Olu KK, Arpagaus A, Hemkens LG, Nordmann AJ. Niacin for primary and secondary prevention of cardiovascular events. Cochrane Database Syst Rev. 2017 Jun 14;6:CD009744. PubMed
  63. Jenkins DJA, Spence JD, Giovannucci EL, et al. Supplemental vitamins and minerals for CVD prevention and treatment. J Am Coll Cardiol 2018;71(22):2570-84. PubMed
  64. Song S, Lee CJ, Oh J, Park S, Kang SM, Lee SH. Effect of Niacin on Carotid Atherosclerosis in Patients at Low-Density Lipoprotein-Cholesterol Goal but High Lipoprotein (a) Level: a 2-Year Follow-Up Study. J Lipid Atheroscler. 2019;8(1):58-66. PubMed
  65. Kimura H, Umemori Y, Yuki D. Anaphylactic shock-like symptoms due to niacin overdose: A case report. J Dermatol 2022;49(8):e287-e288. PubMed
  66. Nawaz N, Mistretta T, Karime C, Lewis J, Wolf E. Cholestatic Drug-Induced Liver Injury in a Patient Taking High-Dose Niacin for Hyperlipidemia. J Investig Med High Impact Case Rep 2024;12:23247096231224349. PubMed

See these in context on the Niacin monograph →

Cassia Cinnamon 20 references
  1. Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=182
  2. Khan A, Safdar M, Ali Khan M, et al. Cinnamon improves glucose and lipids of people with type 2 diabetes. Diabetes Care 2003;26:3215-8. PubMed
  3. De Benito V, Alzaga R. Occupational allergic contact dermatitis from cassia (Chinese cinnamon) as a flavouring agent in coffee. Contact Dermatitis 1999;40:165. PubMed
  4. Drake TE, Maibach HI. Allergic contact dermatitis and stomatitis caused by a cinnamic aldehyde-flavored toothpaste. Arch Dermatol 1976;112:202-3.
  5. Press release. Cinnamon capsules to reduce blood sugar are medicinal products! Efficacy has not been scientifically proven - some products contain high levels of coumarin. Federal Institute of Risk Assessment (BfM), Germany, November 11, 2006. Available a
  6. Felter SP, Vassallo JD, Carlton BD, Daston GP. A safety assessment of coumarin taking into account species-specificity of toxicokinetics. Food Chem Toxicol 2006;44:462-75. PubMed
  7. Crawford P. Effectiveness of cinnamon for lowering hemoglobin A1C in patients with type 2 diabetes: a randomized, controlled trial. J Am Board Fam Med 2009;22:507-12. PubMed
  8. Akilen, R., Tsiami, A., Devendra, D., and Robinson, N. Glycated haemoglobin and blood pressure-lowering effect of cinnamon in multi-ethnic Type 2 diabetic patients in the UK: a randomized, placebo-controlled, double-blind clinical trial. Diabet.Med. 2010; PubMed
  9. Lu T, Sheng H Wu J Cheng Y Zhu J Chen Y. Cinnamon extract improves fasting blood glucose and glycosylated hemoglobin level in Chinese patients with type 2 diabetes. Nutr Res. 2012;32(6):408-412. PubMed
  10. Choi, J., Lee, K. T., Ka, H., Jung, W. T., Jung, H. J., and Park, H. J. Constituents of the essential oil of the Cinnamomum cassia stem bark and the biological properties. Arch Pharm Res 2001;24(5):418-423.
  11. Altschuler JA, Casella SJ, MacKenzie TA, Curtis KM. The effect of cinnamon on A1C among adolescents with type 1 diabetes. Diabetes Care 2007;30(4):813-6. PubMed
  12. Stoecker BR, Zhan Z, Luo R, et al. Cinnamon extract lowers blood glucose in hyperglycemic subjects. FASEB J. 2010;22:722.1 (Abstract only). DOI
  13. Admani S, Hill H, Jacob SE. Cinnamon Sugar Scrub Dermatitis: "Natural" Is Not Always Best. Pediatr Dermatol. 2017;34(1):e42-e43. PubMed
  14. Isaac-Renton M, Li MK, Parsons LM. Cinnamon spice and everything not nice: many features of intraoral allergy to cinnamic aldehyde. Dermatitis. 2015;26(3):116-21. PubMed
  15. Vandersall A, Katta R. Eyelid dermatitis as a manifestation of systemic contact dermatitis to cinnamon. Dermatitis. 2015 Jul-Aug;26(4):189. PubMed
  16. Wickenberg J, Lindstedt S, Nilsson J, Hlebowicz J. Cassia cinnamon does not change the insulin sensitivity or the liver enzymes in subjects with impaired glucose tolerance. Nutr J 2014 Sep 24;13:96. PubMed
  17. Brancheau D, Patel B, Zughaib M. Do cinnamon supplements cause acute hepatitis? Am J Case Rep 2015;16:250-4. PubMed
  18. Shekarchizadeh-Esfahani P, Heydarpour F, Izadi F, Jalili C. The effect of cinnamon supplementation on liver enzymes in adults: A systematic review and meta-analysis of randomized controlled trials. Complement Ther Med 2021;58:102699. PubMed
  19. Bernaola J, Valverde-Monge M, Otal-Buesa M, Cullen D, Heras-Mendaza F. Cinnamon allergic contact cheilitis. Contact Dermatitis 2023;88(5):418-419. PubMed
  20. Patel K, Howard M, Tate B. Cheilitis caused by allergic contact dermatitis to cinnamon in chai tea: A case report. Contact Dermatitis 2023;88(3):239-240. PubMed

See these in context on the Cassia Cinnamon monograph →

Zinc 88 references
  1. Barceloux DG. Zinc. J Toxicol Clin Toxicol 1999;37:279-92.
  2. Eby GA, Davis DR, Halcomb WW. Reduction in duration of common colds by zinc gluconate lozenges in a double-blind study. Antimicrob Agents Chemother 1984;25:20-4. DOI
  3. Smith DS, Helzner EC, Nuttall CE Jr, et al. Failure of zinc gluconate in treatment of acute upper respiratory tract infections. Antimicrob Agents Chemother 1989;33:646-8. PubMed
  4. Blondeau JM. Expanded activity and utility of the new fluoroquinolones: a review. Clin Ther 1999;21:3-40. PubMed
  5. Reyes AJ, Olhaberry JV, Leary WP, et al. Urinary zinc excretion, diuretics, zinc deficiency and some side-effects of diuretics. S Afr Med J 1983;64:936-41.
  6. Kugelmas M. Preliminary observation: oral zinc sulfate replacement is effective in treating muscle cramps in cirrhotic patients. J Am Coll Nutr 2000;19:13-5. PubMed
  7. Hebel SK, ed. Drug Facts and Comparisons. 52nd ed. St. Louis: Facts and Comparisons, 1998.
  8. Chan S, Gerson B, Subramaniam S. The role of copper, molybdenum, selenium, and zinc in nutrition and health. Clin Lab Med 1998;18:673-85. DOI
  9. Brewer GJ, Yuzbasiyan-Gurkan V, Johnson V, et al. Treatment of Wilson's disease with zinc: XI. Interaction with other anticopper agents. J Am Coll Nutr 1993;12:26-30. PubMed
  10. Fosmire GJ. Zinc toxicity. Am J Clin Nutr 1990;51:225-7.
  11. Lomaestro BM, Bailie GR. Absorption interactions with fluoroquinolones. 1995 update. Drug Saf 1995;12:314-33. PubMed
  12. Hansten PD, Horn JR. Drug Interactions Analysis and Management. Vancouver, WA: Applied Therapeutics Inc., 1997 and updates.
  13. Seelig MS. Auto-immune complications of D-penicillamine - A possible result of zinc and magnesium depletion and of pyridoxine inactivation. J Am Coll Nutr 1982;1:207-14. PubMed
  14. Neuvonen PJ. Interactions with the absorption of tetracyclines. Drugs 1976;11:45-54.. PubMed
  15. Hirt M, Nobel S, Barron E. Zinc nasal gel for the treatment of common cold symptoms: A double-blind, placebo-controlled trial. Ear Nose Throat J 2000;79:778-82.. DOI
  16. Simkin PA. Oral zinc sulphate in rheumatoid arthritis. Lancet 1976;2:539-42. PubMed
  17. Wray D. A double-blind trial of systemic zinc sulfate in recurrent aphthous stomatitis. Oral Surg Oral Med Oral Pathol 1982;53:469-72. PubMed
  18. Douglas RM, Miles HB, Moore BW, et al. Failure of effervescent zinc acetate lozenges to alter the course of upper respiratory tract infections in Australian adults. Antimicrob Agents Chemother 1987;31:1263-5. PubMed
  19. Lagiou P, Wuu J, Trichopoulou A, et al. Diet and benign prostatic hyperplasia: a study in Greece. Urology 1999;54:284-90. PubMed
  20. Ewing CI, Gibbs AC, Ashcroft C, David TJ. Failure of oral zinc supplementation in atopic eczema. Eur J Clin Nutr 1991;45:507-10.
  21. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002.
  22. Age-Related Eye Disease Study Research Group. A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age-related macular degeneration and vision loss. AREDS report no. 8. Arch Oph
  23. Greenberg JE, Lynn M, Kirsner RS, et al. Mucocutaneous pigmented macule as a result of zinc deposition. J Cutan Pathol 2002;29:613-5. PubMed
  24. Godfrey HR, Godfrey NJ, Godfrey JC, Riley D. A randomized clinical trial on the treatment of oral herpes with topical zinc oxide/glycine. Altern Ther Health Med 2001;7:49-56.
  25. Turner RB. Ineffectiveness of intranasal zinc gluconate for prevention of experimental rhinovirus colds. Clin Infect Dis 2001;33:1865-70. PubMed
  26. Belongia EA, Berg R, Liu K. A randomized trial of zinc nasal spray for the treatment of upper respiratory illness in adults. Am J Med 2001;111:103-8. PubMed
  27. Mossad SB. Effect of zincum gluconicum nasal gel on the duration and symptom severity of the common cold in otherwise healthy adults. QJM 2003;96:35-43. DOI
  28. Leitzmann MF, Stampfer MJ, Wu K, et al. Zinc supplement use and risk of prostate cancer. J Natl Cancer Inst 2003;95:1004-7.. PubMed
  29. Jafek BW, Linschoten M, Murrow BW. Zicam Induced Anosmia. American Rhinologic Society 49th Annual Fall Scientific Meeting abstract. Orlando, Florida. September 20, 2003. http://app.american-rhinologic.org/programs/2003ARSFallProgram071503.pdf (Accessed 24
  30. Uebayashi H, Hatanaka T, Kanemura F, Tonosaki K. Acute anosmia in the mouse: behavioral discrimination among the four basic taste substances. Physiol Behav 2001;72:291-6.. PubMed
  31. Barrett S. Zicam Marketers Sued. United States District Court Western District of Michigan Southern Division, Filed October 14, 2003, Case No. 4:03CV0146.
  32. Bilici M, Yildirim F, Kandil S, et al. Double-blind, placebo-controlled study of zinc sulfate in the treatment of attention deficit hyperactivity disorder. Prog Neuropsychopharmacol Biol Psychiatry 2004;28:181-90.. PubMed
  33. Polk RE, Healy DP, Sahai J, et al. Effect of ferrous sulfate and multivitamins with zinc on absorption of ciprofloxacin in normal volunteers. Antimicrob Agents Chemother 1989;33:1841-4. PubMed
  34. Mery C, Delrieu F, Ghozlan R, et al. Controlled trial of D-penicillamine in rheumatoid arthritis. Dose effect and the role of zinc. Scand J Rheumatol 1976;5:241-7. PubMed
  35. Penttila O, Hurme H, Neuvonen PJ. Effect of zinc sulfate on the absorption of tetracycline and doxycycline in man. Eur J Clin Pharmacol 1975;9:131-4.
  36. Kondo Y, Yamagata K, Satoh M, et al. Optimal administration schedule of cisplatin for bladder tumor with minimal induction of metallothionein. J Urol 2003;170:2467-70. PubMed
  37. Doz F, Berens ME, Deschepper CF, et al. Experimental basis for increasing the therapeutic index of cis-diamminedicarboxylatocyclobutaneplatinum(II) in brain tumor therapy by a high-zinc diet. Cancer Chemother Pharmacol 1992;29:219-26.
  38. Wester PO. Urinary zinc excretion during treatment with different diuretics. Acta Med Scand 1980;208:209-12. PubMed
  39. Golik A, Modai D, Weissgarten J, et al. Hydrochlorothiazide-amiloride causes excessive urinary zinc excretion. Clin Pharmacol Ther 1987;42:42-4. PubMed
  40. Leary WP, Reyes AJ, Van der Byl K. Urinary magnesium and zinc excretion after two different single doses of amiloride in healthy adults. Curr Ther Res 1983;34:205-16.
  41. McBride K, Slotnick B, Margolis FL. Does intranasal application of zinc sulfate produce anosmia in the mouse? An olfactometric and anatomical study. Chem Senses 2003;28:659-70. PubMed
  42. Burd GD. Morphological study of the effects of intranasal zinc sulfate irrigation on the mouse olfactory epithelium and olfactory bulb. Microsc Res Tech 1993;24:195-213. PubMed
  43. Ducray A, Bondier JR, Michel G, et al. Recovery following peripheral destruction of olfactory neurons in young and adult mice. Eur J Neurosci 2002;15:1907-17. PubMed
  44. Mayer AD, Rosenblatt JS. Peripheral olfactory deafferentation of the primary olfactory system in rats using ZnSO4 nasal spray with special reference to maternal behavior. Physiol Behav 1993;53:587-92. PubMed
  45. DeCook CA, Hirsch AR. Anosmia due to inhalational zinc: a case report (abstract). Chem Senses 2000;25:659.
  46. Tisdall FF, Brown A, Defries RD. Persistent anosmia following zinc sulfate nasal spraying. JPed 1938;18:60-2. DOI
  47. Lawson KA, Wright ME, Subar A, et al. Multivitamin use and risk of prostate cancer in the National Institutes of Health-AARP Diet and Health Study. J Natl Cancer Inst 2007;99:754-64. PubMed
  48. Public Health Advisory. Loss of sense of smell with intranasal cold remedies containing zinc. U.S. Food and Drug Administration, June 16, 2009. Available at: http://www.fda.gov/Drugs/DrugSafety/PublicHealthAdvisories/ucm166059.htm (Accessed 16 June 2009)
  49. Dooren JC. FDA warns against use of Zicam. The Wall Street Journal, June 16, 2009. Available at: http://online.wsj.com/article/SB124516778692319231.html#mod=djemHL?mg=com-wsj (Accessed 16 June 2009).
  50. Alexander TH, Davidson TM. Intranasal zinc and anosmia: the zinc-induced anosmia syndrome. Laryngoscope 2006;116:217-20.
  51. Health Canada / GlaxoSmithKline Consumer Healthcare. Association of long-term, excessive use of zinc-containing Poli-Grip products with myeloneuropathy and blood dyscrasias. February 18, 2010. Available at: http://hc-sc.gc.ca/dhp-mps/alt_formats/pdf/medef
  52. GlaxoSmithKline Consumer Advisory. GlaxoSmithKline (GSK) warns about a potential health risk associated with long-term, excessive use of GSK's zinc-containing denture adhesives Super Polygrip Original, Ultra Fresh and Extra Care. February 18, 2010. Availa
  53. Science M, Johnstone J, Roth DE, et al. Zinc for the treatment of the common cold: a systematic review and meta-analysis of randomized controlled trials. CMAJ 2012;184:E551-61. PubMed
  54. Castilla-Higuero, L., Romero-Gomez, M., Suarez, E., and Castro, M. Acute hepatitis after starting zinc therapy in a patient with presymptomatic Wilson's disease. Hepatology 2000;32(4 Pt 1):877. PubMed
  55. Sharquie, K. E., Najim, R. A., Farjou, I. B., and Al Timimi, D. J. Oral zinc sulphate in the treatment of acute cutaneous leishmaniasis. Clin.Exp.Dermatol. 2001;26(1):21-26. PubMed
  56. Dreno, B., Moyse, D., Alirezai, M., Amblard, P., Auffret, N., Beylot, C., Bodokh, I., Chivot, M., Daniel, F., Humbert, P., Meynadier, J., and Poli, F. Multicenter randomized comparative double-blind controlled clinical trial of the safety and efficacy of
  57. Moore, R. Bleeding gastric erosion after oral zinc sulphate. Br.Med J 3-25-1978;1(6115):754. PubMed
  58. Jafek, B. W., Linschoten, M. R., and Murrow, B. W. Anosmia after intranasal zinc gluconate use. Am J Rhinol. 2004;18(3):137-141. DOI
  59. Simonart, T. and de, Maertelaer, V. Systemic treatments for cutaneous warts: a systematic review. J Dermatolog.Treat. 2012;23(1):72-77. PubMed
  60. Cochran, R. J., Tucker, S. B., and Flannigan, S. A. Topical zinc therapy for acne vulgaris. Int.J Dermatol. 1985;24(3):188-190. DOI
  61. Morgan, A. A. Bleeding gastric erosion after oral zinc sulphate. Br.Med.J. 5-13-1978;1(6122):1283-1284. PubMed
  62. Murphy, J. V. Intoxication following ingestion of elemental zinc. JAMA 6-22-1970;212(12):2119-2120.
  63. Lang, C. J., Rabas-Kolominsky, P., Engelhardt, A., Kobras, G., and Konig, H. J. Fatal deterioration of Wilson's disease after institution of oral zinc therapy. Arch Neurol. 1993;50(10):1007-1008. PubMed
  64. Fjellner, B. Drug-induced lupus erythematosus aggravated by oral zinc therapy. Acta Derm.Venereol. 1979;59(4):368-370. DOI
  65. Varas Lorenzo, M. J. Zinc acexamate and ranitidine in the short- and mid-term management of gastroduodenal ulcers. Curr Ther Res 21986;39:19-29.
  66. Bosch, F. and Jimenez, E. Post-marketing surveillance of zinc acexamate in peptic ulcer treatment. Clin Trials J 1990;27:301-312.
  67. DeCook, C. A. and Hirsch, A. R. Anosmia due to inhalational zinc: a case report (abstract). Chem Senses 2000;25:659.
  68. Crown LA, May JA. Zinc toxicity: denture adhesives, bone marrow failure and polyneuropathy. Tenn Med. 2012 Feb;105(2):39-40, 42.
  69. Dadamio J, Van Tournout M, Teughels W, Dekeyser C, Coucke W, Quirynen M. Efficacy of different mouthrinse formulations in reducing oral malodour: a randomized clinical trial. J Clin Periodontol. 2013 May;40(5):505-13. PubMed
  70. Moyle G, Else L, Jackson A, Back D, Yapa MH, Seymour N, Ringner-Nackter L, Karolia Z, Gazzard B, Boffito M. Coadministration of atazanavir-ritonavir and zinc sulfate: impact on hyperbilirubinemia and pharmacokinetics. Antimicrob Agents Chemother. 2013 Aug PubMed
  71. Zittel S, Ufer F, Gerloff C, Münchau A, Rosenkranz M. Severe myelopathy after denture cream use--is copper deficiency or excess zinc the cause? Clin Neurol Neurosurg. 2014 Jun;121:17-8. PubMed
  72. Jalloh MA, Gregory PJ, Hein D, et al. Dietary supplement interactions with antiretrovirals: a systematic review. Int J STD AIDS. 2017 Jan;28(1):4-15. PubMed
  73. Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents: Drug Interactions between Integrase Inhibitors and Other Drugs. AIDSinfo. July 14, 2016. Available at: https://aidsinfo.nih.gov/guidelines/html/1/adult-and-adolescen
  74. Ding Y, Jia YY, Li F, et al. The effect of staggered administration of zinc sulfate on the pharmacokinetics of oral cephalexin. Br J Clin Pharmacol. 2012 Mar;73(3):422-7. PubMed
  75. Fallah R, Sabbaghzadegan S, Karbasi SA, Binesh F. Efficacy of zinc sulfate supplement on febrile seizure recurrence prevention in children with normal serum zinc level: A randomised clinical trial. Nutrition. 2015;31(11-12):1358-61. PubMed
  76. Lazzerini M, Wanzira H. Oral zinc for treating diarrhoea in children. Cochrane Database Syst Rev. 2016;12:CD005436. PubMed
  77. Mahmoud AM, Al-Alem U, Dabbous F, et al. Zinc intake and risk of prostate cancer: Case-control study and meta-analysis. PLoS One. 2016;11(11):e0165956. PubMed
  78. Nagraj SK, George RP, Shetty N, Levenson D, Ferraiolo DM, Shrestha A. Interventions for managing taste disturbances. Cochrane Database Syst Rev. 2017 Dec 20;12(12):CD010470. PubMed
  79. Yee BE, Richards P, Sui JY, Marsch AF. Serum zinc levels and efficacy of zinc treatment in acne vulgaris: A systematic review and meta-analysis. Dermatol Ther. 2020:e14252. PubMed
  80. Janyajirawong R, Vilaichone RK, Sethasine S. Efficacy of zinc supplement in minimal hepatic encephalopathy: A prospective, randomized controlled study (Zinc-MHE Trial). Asian Pac J Cancer Prev 2021;22(9):2879-2887. PubMed
  81. Nakano M, Nakamura Y, Miyazaki A, Takahashi J. Zinc pharmacotherapy for elderly osteoporotic patients with zinc deficiency in a clinical setting. Nutrients 2021;13(6):1814. PubMed
  82. Tolino E, Skroza N, Mambrin A, et al. An open-label study comparing oral zinc to lymecycline in the treatment of acne vulgaris. J Clin Aesthet Dermatol 2021;14(5):56-58.
  83. Hunter J, Arentz S, Goldenberg J, et al. Zinc for the prevention or treatment of acute viral respiratory tract infections in adults: a rapid systematic review and meta-analysis of randomised controlled trials. BMJ Open. 2021;11(11):e047474. PubMed
  84. Yamazaki K, Kageyama H, Fujiyama T, Ito T, Urano S, Honda T. A case of systemic contact dermatitis due to zinc supplements. Int J Dermatol 2022. PubMed
  85. Magham K, Han J, Eilbert W, Bunney EB. Severe copper deficiency anemia caused by zinc supplement use. Am J Emerg Med 2023;72:222. PubMed
  86. Sivakumar RR, Chinnaiah Govindareddy D, Sahoo J, Bobby Z, Chinnakali P. Effect of daily zinc supplementation for 12 weeks on serum thyroid auto-antibody levels in children and adolescents with autoimmune thyroiditis - a randomized controlled trial. J Pedi PubMed
  87. AlDhasee O, AlMalki H, AlKharashi N, AlJeraisy N, Al Deeb M. Acute zinc sulfate overdose: clinical presentation and management. BMJ Case Rep 2025;18(1):e263899. PubMed
  88. US Food and Drug Administration (FDA). Biktarvy Prescribing Information. October 2024. Available at: https://www.accessdata.fda.gov/drugsatfda_docs/label/2024/210251Orig1s020lbl.pdf. Accessed July 16, 2025.

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Eurycoma Longifolia 4 references
  1. Salman SA, Amrah S, Wahab MS, et al. Modification of propranolol's bioavailability by Eurycoma longifolia water-based extract. J Clin Pharm Ther 2010;35:691-6. PubMed
  2. Tambi MI, Imran MK, Henkel RR. Standardised water-soluble extract of Eurycoma longifolia, Tongkat ali, as testosterone booster for managing men with late-onset hypogonadism? Andrologia 2011 Jun 15. doi: 10.1111/j.1439-0272.2011.01168.x. [Epub ahead of pri PubMed
  3. Han YM, Kim IS, Rehman SU, Choe K, Yoo HH. In vitro evaluation of the effects of Eurycoma longifolia extract on CYP-mediated drug metabolism. Evid Based Complement Alternat Med 2015;2015:631329.
  4. Chinnappan SM, George A, Pandey P, Narke G, Choudhary YK. Effect of Eurycoma longifolia standardised aqueous root extract-Physta ® on testosterone levels and quality of life in ageing male subjects: a randomised, double-blind, placebo-controlled multicent

See these in context on the Eurycoma Longifolia monograph →

Horny Goat Weed 11 references
  1. Cirigliano MD, Szapary PO. Horny goat weed for erectile dysfunction. Alt Med Alert 2001;4:19-22.
  2. Partin JF, Pushkin YR. Tachyarrhythmia and hypomania with horny goat weed. Psychosomatics 2004;45:536-7. PubMed
  3. De Naeyer A, Pocock V, Milligan S, De Keukeleire D. Estrogenic activity of a polyphenolic extract of the leaves of Epimedium brevicornum. Fitoterapia 2005;76:35-40. PubMed
  4. Zhang CZ, Wang SX, Zhang Y, et al. In vitro estrogenic activities of Chinese medicinal plants traditionally used for the management of menopausal symptoms. J Ethnopharmacol 2005;98:295-300. PubMed
  5. Yap SP, Shen P, Li J, et al. Molecular and pharmacodynamic properties of estrogenic extracts from the traditional Chinese medicinal herb, Epimedium. J Ethnopharmacol 2007;113:218-24. PubMed
  6. Yan, F. F., Liu, Y., Liu, Y. F., and Zhao, Y. X. Herba Epimedii water extract elevates estrogen level and improves lipid metabolism in postmenopausal women. Phytother.Res. 2008;22(9):1224-1228. PubMed
  7. Ramanathan VS, Mitropoulos E, Shlopov B, et al. An Enzyte'ing' case of acute hepatitis. J Clin Gastroenterol 2011;45(9):834-5. PubMed
  8. Zhong Q, Shi Z, Zhang L, et al. The potential of Epimedium koreanum Nakai for herb-drug interaction. J Pharm Pharmacol 2017;69(10):1398-408. doi: 10.1111/jphp.12773.
  9. Irfan M, Kwon TH, Lee DH, et al. Antiplatelet and Antithrombotic Effects of Epimedium koreanum Nakai. Evid Based Complement Alternat Med. Apr 2021;2021:7071987. PubMed
  10. Tan K, Yang W, Pang L, Hou F. Differences in clinical characteristics among 726 patients with Chinese herbal medicine- or Western medicine-induced liver injury. Medicine (Baltimore) 2022;101(32):e29909. PubMed
  11. Li K, Yu XH, Maskey AR, et al. Cytochrome P450 3A4 suppression by epimedium and active compound kaempferol leads to synergistic anti-inflammatory effect with corticosteroid. Front Pharmacol 2023;13:1042756. PubMed

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DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

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