Interactions on record — worth a quick check against your medications. Based on 9 of 10 ingredients. Check your meds →
Dietary supplement

Herbal Immune Support Ingredients & Drug Interactions

by Dr. Mercola

Herbal Immune Support label
See full label image
Capsule Category: Other Combinations
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Herbal Immune Support 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: Moderate

Herbal Immune Support is a dietary supplement by Dr. Mercola with 10 active ingredients. Its ingredients are commonly taken for bone health and osteoporosis, correcting vitamin d deficiency, immune system support.Based on those ingredients, 1,092 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Bee Propolis, Powder, Peppermint, Vitamin D3. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Herbal Immune Support by Dr. Mercola

Ask about any prescription or over-the-counter medication and we check it for interactions with Herbal Immune Support by Dr. Mercola — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Herbal Immune Support by Dr. Mercola

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 Jul 11, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 10 of its 10 active ingredients.
  • No proprietary blends here — you can verify the dose of every single component.

This product has 10 ingredients total. The active ones are Vitamin D3 (for bone and immune health), Peppermint (for digestive comfort), bee propolis powder (from honeybee hives), olive leaf extract, Vitamin C, elder flower extract, dimethylglycine hydrochloride, acerola fruit extract (a natural vitamin C source), oregano leaf oil, and yarrow.

The capsule itself contains three inactive ingredients—hydroxypropyl methylcellulose, microcrystalline cellulose, and maltodextrin—which are binders and fillers.

Does it work?

Moderate evidence
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
Moderate

Some clinical evidence supports this product's ingredients for its stated purpose, but it isn't conclusive.

Why this rating?
  • The label markets this product for: immune support and detoxification.
  • We looked for evidence on: Common cold, Acute bronchitis, Bronchitis, Cough, Coronavirus disease 2019 (COVID-19), Chronic fatigue syndrome (CFS) — and 4 related terms.
  • The strongest evidence on file: Vitamin D is rated "Possibly Effective" for Coronavirus disease 2019 (COVID-19) (Natural Medicines).
  • Also on file: Vitamin C is rated "Possibly Ineffective" for Acute bronchitis.
  • Also on file: Vitamin C is rated "Likely Ineffective" for Coronavirus disease 2019 (COVID-19).

The evidence is mixed. Vitamin D3 is established as effective for rickets, osteomalacia (soft bones), renal bone disease, and hypoparathyroidism—serious deficiency states.

Peppermint is likely effective for irritable bowel syndrome and possibly effective for indigestion and nausea. Bee propolis is possibly effective for oral sores and cold sores.

Vitamin C is effective for deficiency and possibly effective for anemia and some infections. For the remaining ingredients—acerola, olive leaf, oregano, yarrow, and dimethylglycine—the data we hold rates the evidence as insufficient; we don't have established proof they work for the purposes they're included here.

The evidence, ingredient by ingredient Vitamin D Peppermint Propolis Olive Vitamin C American Elder Acerola Oregano

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 9 of the 9 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 9 of 9.
  • General safety write-ups exist for 9 of 9.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

At recommended doses, Vitamin D3 is generally well tolerated, though very high doses over time can cause toxicity with symptoms like high blood calcium. Peppermint is generally well tolerated orally, though concentrated oil can cause abdominal pain, heartburn, or anal burning; it's likely safe in pregnancy.

Bee propolis is well tolerated short-term but carries a risk of allergic reactions, especially in people sensitive to bee products—it should be avoided in pregnancy and breastfeeding. Vitamin C is generally well tolerated at normal doses but can cause kidney stones, osmotic diarrhea, and nausea at very high doses above 2 grams daily.

Acerola is generally considered safe in food amounts. Olive leaf extract is less studied in concentrated form.

Oregano used as food is safe, but medicinal amounts should be avoided in pregnancy. Yarrow has limited human safety data and should be avoided in pregnancy and breastfeeding due to concerns about uterine effects.

Side effects, ingredient by ingredient Vitamin D Peppermint Propolis Olive Vitamin C American Elder Acerola Oregano

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 8 of the 9 matched ingredients can interact with medications — Yarrow, Propolis, Acerola, Oregano, Peppermint, among others.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; immunosuppressants / transplant drugs; cancer treatments; diabetes medications; heart-rhythm medications; lithium.
  • For scale: 1,093 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.

Check your medications against this product if you take blood thinners (warfarin, other anticoagulants), heart rhythm drugs (verapamil, diltiazem, digoxin), blood pressure or cholesterol drugs, immunosuppressants like cyclosporine, lithium, diabetes drugs, or any medication your liver breaks down. These carry Moderate-severity interactions with vitamin D, peppermint, propolis, vitamin C, acerola, or oregano in this formula.

If your doctor prescribed any of these, use the medication checker on this page to verify safety before you begin.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with some supporting evidence for its stated purpose. Moderate medication interactions have been identified, and safety information is well characterized.

If you don't take any prescription medications and want natural immune support, this formula is worth discussing with your pharmacist. But if you're on any blood thinners, heart drugs, cholesterol medications, or anything metabolized by your liver, you need to check your exact medications first—the interaction potential is real.

Propolis and oregano aren't right for people trying to avoid bleeding or manage blood sugar. Talk to your pharmacist or doctor before you start, especially if you're pregnant, breastfeeding, or taking anything for a chronic condition.

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

Assessment coverage: 9 of 10 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Feb 23, 2025.

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 Herbal Immune Support, straight from the product label.

Brand Dr. Mercola
Barcode (UPC) 810094210908
Net contents 90 Capsule(s)
Market status On market
Date entered into DSLD Feb 23, 2025
DSLD ID 327171
Product type Other Combinations
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (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 Herbal Immune Support by Dr. Mercola, 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:
3 Capsule(s)
Maximum serving Sizes:
3 Capsule(s)
Servings per container
30
UPC/BARCODE
810094210908
IngredientAmount% DV
Vitamin D362.5 mcg313%
Peppermint195 mg--
Bee Propolis, Powder50 mg--
Olive Leaf Extract25 mg--
Vitamin C60 mg67%
Elder Flower Extract160 mg--
Dimethylglycine Hydrochloride150 mg--
Acerola Fruit Extract300 mg--
Oregano leaf Oil50 mg--
Yarrow200 mg--

Other ingredients: Hydroxypropyl Methylcellulose, Microcrystalline Cellulose, Maltodextrin

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.
Suggested/Recommended/Usage/Directions

Suggested Use: Adults, as a dietary supplement, take three (3) capsules twice daily for up to ten (10) days.

Precautions

Keep out of reach of children.

Do not use if safety seal is broken.

If you are nursing, pregnant, taking medication or have a medical condition, consult your physician before taking this product.

FDA Disclaimer Statement

This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Formulation

Immune Support Detoxification Support

Formula

Antioxidant

FDA Statement of Identity

Dietary Supplement

General Statements

Providing quality products since 2001.

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

See for yourself

Herbal Immune Support by Dr. Mercola label

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

Herbal Immune Support 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 Herbal Immune Support by Dr. Mercola

These are the 10 active ingredients this product is made of. Select any to open its full monograph.

Serving size3 Capsule(s) Dosage formCapsule Servings per container30 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 D3

Interacts with
715 drugs
62.5 mcg per serving Form: Cholecalciferol

Vitamin D is a fat-soluble vitamin that helps your body absorb calcium and is important for healthy bones, muscles, and immune function. Many people,...

Vitamin D3 monograph & interactions

Peppermint

Interacts with
796 drugs
195 mg per serving

Peppermint is a popular herb with the best evidence supporting enteric-coated peppermint oil for easing IBS symptoms. It is generally well tolerated f...

Peppermint monograph & interactions

Bee Propolis, Powder

Interacts with
921 drugs
50 mg per serving

Propolis is a natural, resin-like substance made by bees that has antimicrobial and anti-inflammatory properties in lab studies. Early research sugges...

Bee Propolis, Powder monograph & interactions

Olive Leaf Extract

No known
interactions
25 mg per serving

Olive comes from the same tree that gives us olives and olive oil, and its leaf and fruit contain antioxidant compounds like oleuropein and hydroxytyr...

Olive Leaf Extract monograph & interactions

Vitamin C

Interacts with
207 drugs
60 mg per serving Form: Acerola Fruit Extract

Vitamin C (ascorbic acid) is an essential nutrient your body needs but cannot make, so you must get it from food or supplements. It's important for im...

Vitamin C monograph & interactions

Elder Flower Extract

Interacts with
644 drugs
160 mg per serving Form: Sambucus nigra Flower Extract

American elder is a North American plant whose cooked, ripe berries and flowers are used mainly for colds, flu, and general immune support. The scienc...

Elder Flower Extract monograph & interactions

Dimethylglycine Hydrochloride

150 mg per serving

Acerola Fruit Extract

Interacts with
128 drugs
300 mg per serving Form: Malpighia emarginata Fruit Extract

Acerola is a small tropical fruit prized for its very high natural vitamin C content, and it is mostly used as a food-based source of vitamin C and an...

Acerola Fruit Extract monograph & interactions

Oregano leaf Oil

Interacts with
208 drugs
50 mg per serving

Oregano is a common Mediterranean cooking herb that is also sold as a concentrated oil or supplement, often standardized for a compound called carvacr...

Oregano leaf Oil monograph & interactions

Yarrow

Interacts with
1 drug
200 mg per serving Form: Achillea millefolium

Yarrow is a traditional herb long used for wounds, digestive complaints, and colds, but high-quality human studies are very limited, so its benefits a...

Yarrow monograph & interactions

Other (inactive) ingredients: Hydroxypropyl Methylcellulose, Microcrystalline Cellulose, Maltodextrin. These complete the product’s ingredient list but are not active constituents.

Interaction report

Herbal Immune Support by Dr. Mercola Drug Interactions

Want to check YOUR meds against Herbal Immune Support?

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
1,092Drugs
1,086 Moderate 6 Minor

Ingredients driving the most interactions

Bee Propolis, Powder 921
Peppermint 796
Vitamin D3 715
Elder Flower Extract 644
Oregano leaf Oil 208

Individual Drug Interactions

The ingredients in Herbal Immune Support interact with 1,092 drugs. Click any drug to see the details.

8 of the 10 ingredients in Herbal Immune Support interact with drugs. Each result below shows which ingredient is responsible. Bee Propolis, Powder Peppermint Vitamin D3 Elder Flower Extract Oregano leaf Oil Vitamin C Acerola Fruit Extract Yarrow

Each ingredient & the kinds of drugs it affects

For each ingredient in Herbal Immune Support 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.

Bee Propolis, Powder8 drug types · 921 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, propolis might increase the risk of bleeding when taken with antiplatelet or anticoagulant drugs.
In vitro research shows that propolis water extract and the propolis constituent, caffeic acid phenethyl ester, can inhibit platelet aggregation. Additionally, evidence from an animal model shows that taking propolis in addition to warfarin decreases INR, suggesting that propolis can decrease the effectiveness of warfarin.

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

Theoretically, high doses of propolis might increase blood levels of drugs metabolized by CYP1A2.
In vitro research shows that propolis extract can inhibit CYP1A2. However, animal research shows that propolis extract does not significantly affect CYP1A2 activity when administered to rats at doses up to 250 mg/kg. It is postulated that the constituents of propolis that inhibit CYP1A2 in vitro do not have significant effects in vivo due to low bioavailability and hepatic first-pass effect. This effect has not been reported in humans.

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

Theoretically, high doses of propolis might increase blood levels of drugs metabolized by CYP2C19.
In vitro research shows that propolis extract can inhibit CYP2C19. However, animal research shows that propolis extract does not significantly affect CYP2C19 activity when administered to rats at doses up to 250 mg/kg. It is postulated that the constituents of propolis that inhibit CYP2C19 in vitro do not have significant effects in vivo due to low bioavailability and hepatic first-pass effect. This effect has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2C9 (Cyp2C9) Substrates

Theoretically, high doses of propolis might increase blood levels of drugs metabolized by CYP2C9.
In vitro research shows that propolis extract can inhibit CYP2C9. However, animal research shows that propolis extract does not significantly affect CYP2C9 activity when administered to rats at doses up to 250 mg/kg. It is postulated that the constituents of propolis that inhibit CYP2C9 in vitro do not have significant effects in vivo due to low bioavailability and hepatic first-pass effect. This effect has not been reported in humans.

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

Theoretically, high doses of propolis might increase blood levels of drugs metabolized by CYP2D6.
In vitro research shows that propolis extract can inhibit CYP2D6. However, animal research shows that propolis extract does not significantly affect CYP2D6 activity when administered to rats at doses up to 250 mg/kg. It is postulated that the constituents of propolis that inhibit CYP2D6 in vitro do not have significant effects in vivo due to low bioavailability and hepatic first-pass effect. This effect has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2E1 (Cyp2E1) Substrates

Theoretically, propolis might increase levels of drugs metabolized by CYP2E1.
In vitro research shows that propolis can inhibit CYP2E1. This effect has not been reported in humans.

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

Theoretically, high doses of propolis might increase blood levels of drugs metabolized by CYP3A4.
Some in vitro research shows that propolis extract can inhibit CYP3A4; however, other in vitro research shows that propolis has no effect on CYP3A4 activity. Furthermore, animal research shows that propolis extract does not significantly affect CYP3A4 activity when administered to rats at doses up to 250 mg/kg. It is postulated that the constituents of propolis that might in inhibit CYP3A4 in vitro do not have significant effects in vivo due to low bioavailability and hepatic first-pass effect. This effect has not been reported in humans.

Likelihood Possible Evidence D
Warfarin (Coumadin)

Theoretically, propolis might decrease the effectiveness of warfarin.
Animal research shows that taking propolis in addition to warfarin decreases the international normalized ratio (INR). This effect has not been reported in humans.

Likelihood Possible Evidence D
Bee Propolis, Powder full monograph & interactions

Peppermint5 drug types · 796 drugs

Cyclosporine (Neoral, Sandimmune)

Theoretically, peppermint oil might increase the levels and adverse effects of cyclosporine.
In animal research, peppermint oil inhibits cyclosporine metabolism and increases cyclosporine levels. Inhibition of cytochrome P450 3A4 (CYP3A4) may be partially responsible for this interaction. An interaction between peppermint oil and cyclosporine has not been reported in humans.

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

Theoretically, peppermint might increase the levels of CYP2C19 substrates.
In vitro research shows that peppermint oil inhibits CYP2C19. So far, this interaction has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2C9 (Cyp2C9) Substrates

Theoretically, peppermint might increase the levels of CYP2C9 substrates.
In vitro research shows that peppermint oil inhibits CYP2C9. So far, this interaction has not been reported in humans.

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

Theoretically, peppermint might increase the levels of CYP3A4 substrates.
Clinical research in healthy volunteers shows that a single dose of peppermint oil 600 mg inhibits CYP3A4 enzymes and increases the AUC of felodipine, a CYP3A4 substrate. However, in vitro research suggests that peppermint oil only inhibits CYP3A4 at very high concentrations.

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

Theoretically, peppermint might increase the levels of CYP1A2 substrates.
In vitro and animal research shows that peppermint oil and peppermint leaf inhibit CYP1A2. However, in clinical research, peppermint tea did not significantly affect the metabolism of caffeine, a CYP1A2 substrate. It is possible that the 6-day duration of treatment may have been too short to identify a difference.

Likelihood Possible Evidence B
Peppermint full monograph & interactions

Vitamin D38 drug types · 715 drugs

Aluminum

Vitamin D might increase aluminum absorption and toxicity, but this has only been reported in people with renal failure.
The protein that transports calcium across the intestinal wall can also bind and transport aluminum. This protein is stimulated by vitamin D, which may therefore increase aluminum absorption. This mechanism may contribute to increased aluminum levels and toxicity in people with renal failure, when they take vitamin D and aluminum-containing phosphate binders chronically.

Likelihood Probable Evidence B
Atorvastatin (Lipitor)

Vitamin D might reduce absorption of atorvastatin.
A small, low-quality clinical study shows that taking vitamin D reduces levels of atorvastatin and its active metabolites by up to 55%. However, while atorvastatin levels decreased, total cholesterol, low-density lipoprotein (LDL) cholesterol, and high-density lipoprotein (HDL) cholesterol levels did not substantially change. Atorvastatin is metabolized in the gut by CYP3A4 enzymes, and researchers theorized that vitamin D might induce CYP3A4, causing reduced levels of atorvastatin. However, this proposed mechanism was not specifically studied.

Likelihood Probable Evidence B
Calcipotriene (Dovonex)

Taking calcipotriene with vitamin D increases the risk for hypercalcemia.
Calcipotriene is a vitamin D analog used topically for psoriasis. It can be absorbed in sufficient amounts to cause systemic effects, including hypercalcemia. Theoretically, combining calcipotriene with vitamin D supplements might increase the risk of hypercalcemia.

Likelihood Probable Evidence D
Digoxin (Lanoxin)

Theoretically, hypercalcemia induced by high-dose vitamin D can increase the risk of arrhythmia from digoxin.
High doses of vitamin D can cause hypercalcemia. Hypercalcemia increases the risk of fatal cardiac arrhythmias with digoxin. Avoid vitamin D doses above the tolerable upper intake level (4000 IU daily for adults) and monitor serum calcium levels in people taking vitamin D and digoxin concurrently.

Likelihood Possible Evidence D
Diltiazem (Cardizem, Others)

Theoretically, hypercalcemia induced by high-dose vitamin D can reduce the therapeutic effects of diltiazem for arrhythmia.
High doses of vitamin D can cause hypercalcemia. Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation. Theoretically this could also occur with diltiazem. Avoid vitamin D doses above the tolerable upper intake level (4000 IU daily for adults) and monitor serum calcium levels in people taking vitamin D and diltiazem concurrently.

Likelihood Probable Evidence B
Thiazide Diuretics

Theoretically, taking thiazide diuretics and high-dose vitamin D can increase the risk of hypercalcemia.
Thiazide diuretics decrease urinary calcium excretion, which could lead to hypercalcemia if vitamin D supplements are taken concurrently. This has been reported in people being treated with vitamin D for hypoparathyroidism, and also in elderly people with normal parathyroid function who were taking a thiazide, vitamin D, and calcium-containing antacids daily.

Likelihood Probable Evidence D
Verapamil (Calan, Others)

Hypercalcemia induced by high-dose vitamin D can reduce the therapeutic effects of verapamil for arrhythmia.
Hypercalcemia due to high doses of vitamin D can reduce the effectiveness of verapamil in atrial fibrillation. Avoid vitamin D doses above the tolerable upper intake level (4000 IU daily for adults) and monitor serum calcium levels in people taking vitamin D and verapamil concurrently.

Likelihood Probable Evidence B
Cytochrome P450 3A4 (Cyp3A4) Substrates

Vitamin D might induce CYP3A4 enzymes and reduce the bioavailability of CYP3A4 substrates.
There is some concern that vitamin D might induce CYP3A4. In vitro research suggests that vitamin D induces CYP3A4 transcription. Additionally, observational research has found that increased UV light exposure and serum vitamin D levels are associated with decreased serum levels of CYP3A4 substrates such as tacrolimus and sirolimus, while no association between UV light exposure or vitamin D levels and levels of mycophenolic acid, a non-CYP3A4 substrate, was found. A small, low-quality clinical study shows that taking vitamin D reduces levels of the CYP3A4 substrate atorvastatin and its active metabolites by up to 55%; however, the clinical effects of atorvastatin were not reduced. While researchers theorized that vitamin D might induce CYP3A4, this proposed mechanism was not specifically studied.

Likelihood Possible Evidence D
Vitamin D3 full monograph & interactions

Elder Flower Extract2 drug types · 644 drugs

Cytochrome P450 3A4 (Cyp3A4) Substrates

Theoretically, taking American elder might increase levels of CYP3A4 substrates.
In vitro research shows that American elder inhibits CYP3A4 enzymes.

Likelihood Possible Evidence D
Lithium

Theoretically, American elder might reduce excretion and increase levels of lithium.
American elder is thought to have diuretic properties. Theoretically, American elder might reduce the excretion of lithium, increasing serum levels.

Likelihood Probable Evidence D
Elder Flower Extract full monograph & interactions

Oregano leaf Oil2 drug types · 208 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, oregano might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.
In vitro research shows that aristolochic acid isolated from oregano leaves has antithrombin activity. It has also been reported that oregano oil inhibits arachidonic acid-induced, and ADP-induced, platelet aggregation.

Likelihood Possible Evidence D
Antidiabetes Drugs

Theoretically, oregano might increase the risk for hypoglycemia when taken with antidiabetes drugs.
In vitro and animal research shows that oregano extracts might lower blood glucose levels.

Likelihood Possible Evidence D
Oregano leaf Oil full monograph & interactions

Vitamin C13 drug types · 207 drugs

Alkylating Agents

Theoretically, antioxidant effects of vitamin C might reduce the effectiveness of alkylating agents.
The use of antioxidants like vitamin C during chemotherapy is controversial. There is concern that antioxidants could reduce the activity of chemotherapy drugs that generate free radicals, such as cyclophosphamide, chlorambucil, carmustine, busulfan, and thiotepa. In contrast, some researchers theorize that antioxidants might make chemotherapy more effective by reducing oxidative stress that could interfere with apoptosis (cell death) of cancer cells. More evidence is needed to determine what effect, if any, antioxidants such as vitamin C have on chemotherapy.

Likelihood Possible Evidence D
Aluminum

Vitamin C can increase the amount of aluminum absorbed from aluminum compounds.
Research in animals and humans shows that vitamin C increases aluminum absorption, theoretically by chelating aluminum and keeping it in solution where it is available for absorption. In people with normal renal function, urinary excretion of aluminum will likely increase, making aluminum retention and toxicity unlikely. Patients with renal failure who take aluminum-containing compounds such as phosphate binders should avoid vitamin C supplements in doses above the recommended dietary allowances.

Likelihood Probable Evidence B
Antitumor Antibiotics

Theoretically, the antioxidant effects of vitamin C might reduce the effectiveness of antitumor antibiotics.
The use of antioxidants like vitamin C during chemotherapy is controversial. There is concern that antioxidants could reduce the activity of chemotherapy drugs which generate free radicals, such as doxorubicin. In contrast, some researchers theorize that antioxidants might make chemotherapy more effective by reducing oxidative stress that could interfere with apoptosis (cell death) of cancer cells. More evidence is needed to determine what effects, if any, antioxidants such as vitamin C have on chemotherapy.

Likelihood Possible Evidence D
Estrogens

Vitamin C might increase blood levels of estrogens.
Increases in plasma estrogen levels of up to 55% occur under some circumstances when vitamin C is taken concurrently with oral contraceptives or hormone replacement therapy, including topical products. It is suggested that vitamin C prevents oxidation of estrogen in the tissues, regenerates oxidized estrogen, and reduces sulfate conjugation of estrogen in the gut wall. When tissue levels of vitamin C are high, these processes are already maximized and supplemental vitamin C does not have any effect on estrogen levels. Increases in plasma estrogen levels may occur when patients who are deficient in vitamin C take supplements. Monitor these patients for estrogen-related side effects.

Likelihood Probable Evidence B
Fluphenazine (Prolixin)

Theoretically, vitamin C might decrease levels of fluphenazine.
In one patient there was a clinically significant decrease in fluphenazine levels when vitamin C (500 mg twice daily) was started. The mechanism is not known, and there is no further data to confirm this interaction.

Likelihood Possible Evidence D
Indinavir (Crixivan)

Vitamin C can modestly reduce indinavir levels.
One pharmacokinetic study shows that taking vitamin C 1 gram orally once daily along with indinavir 800 mg orally three times daily reduces the area under the concentration-time curve of indinavir by 14%. The mechanism of this interaction is unknown, but it is unlikely to be clinically significant in most patients. The effect of higher doses of vitamin C on indinavir levels is unknown.

Likelihood Probable Evidence B
Levothyroxine (Synthroid, Others)

Vitamin C can increase levothyroxine absorption.
Two clinical studies in adults with poorly controlled hypothyroidism show that swallowing levothyroxine with a glass of water containing vitamin C 500-1000 mg in solution reduces thyroid stimulating hormone (TSH) levels and increases thyroxine (T4) levels when compared with taking levothyroxine alone. This suggests that vitamin C increases the oral absorption of levothyroxine, possibly due to a reduction in pH.

Likelihood Probable Evidence B
Warfarin (Coumadin)

High-dose vitamin C might reduce the levels and effectiveness of warfarin.
Vitamin C in high doses may cause diarrhea and possibly reduce warfarin absorption. There are reports of two people who took up to 16 grams daily of vitamin C and had a reduction in prothrombin time. Lower doses of 5-10 grams daily can also reduce warfarin absorption. In many cases, this does not seem to be clinically significant. However, a case of warfarin resistance has been reported for a patient who took vitamin C 500 mg twice daily. Cessation of vitamin C supplementation resulted in a rapid increase in international normalized ratio (INR). Tell patients taking warfarin to avoid taking vitamin C in excessively high doses (greater than 10 grams daily). Lower doses may be safe, but the anticoagulation activity of warfarin should be monitored. Patients who are stabilized on warfarin while taking vitamin C should avoid adjusting vitamin C dosage to prevent the possibility of warfarin resistance.

Likelihood Possible Evidence D
Acetaminophen (Tylenol, Others)

High-dose vitamin C might slightly prolong the clearance of acetaminophen.
A small pharmacokinetic study in healthy volunteers shows that taking high-dose vitamin C (3 grams) 1.5 hours after taking acetaminophen 1 gram slightly increases the apparent half-life of acetaminophen from around 2.3 hours to 3.1 hours. Ascorbic acid competitively inhibits sulfate conjugation of acetaminophen. However, to compensate, elimination of acetaminophen glucuronide and unconjugated acetaminophen increases. This effect is not likely to be clinically significant.

Likelihood Probable Evidence B
Aspirin

Acidification of the urine by vitamin C might increase aspirin levels.
It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels. However, short-term use of up to 6 grams daily of vitamin C does not seem to affect urinary pH or salicylate excretion, suggesting this interaction is not clinically significant.

Likelihood Possible Evidence B
Choline Magnesium Trisalicylate (Trilisate)

Acidification of the urine by vitamin C might increase choline magnesium trisalicylate levels.
It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels. However, short-term use of up to 6 grams daily of vitamin C does not seem to affect urinary pH or salicylate excretion, suggesting this interaction probably is not clinically significant.

Likelihood Possible Evidence B
Niacin

Vitamin C might decrease the beneficial effects of niacin on high-density lipoprotein (HDL) cholesterol levels.
A combination of niacin and simvastatin (Zocor) effectively raises HDL cholesterol levels in patients with coronary disease and low HDL levels. Clinical research shows that taking a combination of antioxidants (vitamin C, vitamin E, beta-carotene, and selenium) along with niacin and simvastatin (Zocor) attenuates this rise in HDL, specifically the HDL-2 and apolipoprotein A1 fractions, by more than 50% in patients with coronary disease. It is not known whether this adverse effect is due to a single antioxidant such as vitamin C, or to the combination. It also is not known whether it will occur in other patient populations.

Likelihood Possible Evidence A
Salsalate (Disalcid)

Acidification of the urine by vitamin C might increase salsalate levels.
It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels. However, short-term use of up to 6 grams/day vitamin C does not seem to affect urinary pH or salicylate excretion, suggesting this interaction probably is not clinically significant.

Likelihood Possible Evidence B
Vitamin C full monograph & interactions

Acerola Fruit Extract6 drug types · 128 drugs

Alkylating Agents

Theoretically, the antioxidant effects of acerola might reduce the effectiveness of alkylating agents.
Acerola contains vitamin C, an antioxidant. There is concern that antioxidants might reduce the activity of chemotherapy drugs that generate free radicals, such as alkylating agents. In contrast, other researchers theorize that antioxidants might make alkylating chemotherapy more effective by reducing oxidative stress that could interfere with apoptosis (cell death) of cancer cells. More evidence is needed to determine what effect, if any, antioxidants such as vitamin C have on chemotherapy.

Likelihood Possible Evidence D
Antitumor Antibiotics

Theoretically, the antioxidant effects of acerola might reduce the effectiveness of antitumor antibiotics.
Acerola contains vitamin C, an antioxidant. There is concern that antioxidants might reduce the activity of chemotherapy drugs that generate free radicals, such as antitumor antibiotics. In contrast, other researchers theorize that antioxidants might make antitumor antibiotic chemotherapy more effective by reducing oxidative stress that could interfere with apoptosis (cell death) of cancer cells. More evidence is needed to determine what effects, if any, antioxidants such as vitamin C have on antitumor antibiotic chemotherapy.

Likelihood Possible Evidence D
Aluminum

Theoretically, concomitant use of acerola with aluminum salts might increase the amount of aluminum absorbed.
Acerola contains vitamin C. It is thought that vitamin C chelates aluminum, keeping it in solution and available for absorption. In people with normal renal function, urinary excretion of aluminum likely increases, making aluminum retention and toxicity unlikely. However, patients with renal failure who take aluminum-containing compounds, such as phosphate binders, should avoid acerola in doses that provide more vitamin C than the recommended dietary allowances.

Likelihood Possible Evidence D
Aspirin

Theoretically, acerola might reduce the clearance of aspirin; however, its vitamin C content is likely too low to produce clinically significant effects.
Acerola contains vitamin C. It has been suggested that acidification of the urine by vitamin C can decrease the urinary excretion of salicylates, increasing plasma salicylate levels. However, short-term use of up to 6 grams daily of vitamin C does not seem to affect urinary pH or salicylate excretion. The vitamin C content of acerola is typically about 2000 mg per 100 grams. Thus, a clinically significant interaction between acerola and aspirin is unlikely.

Likelihood Unlikely Evidence B
Estrogens

Theoretically, concomitant use of acerola with estrogens might increase estrogenic effects.
Acerola contains vitamin C. Increases in plasma estrogen levels of up to 55% have occurred under some circumstances when vitamin C is taken concurrently with oral contraceptives or hormone replacement therapy, including topical products. It is suggested that vitamin C prevents oxidation of estrogen in the tissues, regenerates oxidized estrogen, and reduces sulfate conjugation of estrogen in the gut wall. When tissue levels of vitamin C are high, these processes are already maximized and supplemental vitamin C does not have any effect on estrogen levels. However, increases in plasma estrogen levels may occur when women who are deficient in vitamin C take supplements.

Likelihood Possible Evidence D
Warfarin (Coumadin)

Theoretically, acerola might reduce the effectiveness of warfarin; however, its vitamin C content is likely too low to produce clinically significant effects.
Acerola contains vitamin C. High doses of vitamin C may reduce the response to warfarin, possibly by causing diarrhea and reducing warfarin absorption. This occurred in two people who took up to 16 grams daily of vitamin C, and resulted in decreased prothrombin time. Lower doses of 5-10 grams daily of vitamin C can also reduce warfarin absorption, but this does not seem to be clinically significant. The vitamin C content of acerola is typically about 2000 mg per 100 grams. Thus, a clinically significant interaction between acerola and warfarin is unlikely.

Likelihood Unlikely Evidence D
Acerola Fruit Extract full monograph & interactions

Yarrow1 drug type · 1 drug

Lithium

Theoretically, taking yarrow with lithium might increase the levels and adverse effects of lithium.
Animal research shows that yarrow has diuretic activity. Theoretically, due to these potential diuretic effects, yarrow might reduce excretion and increase levels of lithium. The dose of lithium might need to be decreased.

Likelihood Probable Evidence D
Yarrow full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Herbal Immune Support, from the product label.

Dr. Mercola

See all Dr. Mercola products
Name
NHP
Street Address
125 SW 3rd Place
City
Cape Coral
State
FL
ZipCode
33991
Phone Number
(877) 985-2696
Pharmacist Counseling Corner

Herbal Immune Support by Dr. Mercola: Common Questions

Does Herbal Immune Support by Dr. Mercola interact with any medications?
Yes. Based on its ingredients, Herbal Immune Support has a known interaction with 1,092 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Herbal Immune Support contains 10 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.
Is this safe to take while pregnant?
Peppermint is likely safe in pregnancy. Vitamin D at recommended doses is often used in pregnancy but only under your doctor's guidance. Bee propolis, oregano, and yarrow should be avoided—the safety data advises against them or there isn't enough information. For the other ingredients, safety data isn't on file. Talk with your doctor or pharmacist before starting any of this during pregnancy.
Is this safe while breastfeeding?
Peppermint is likely safe. Bee propolis, oregano, and yarrow should be avoided while breastfeeding due to insufficient safety information. For the other ingredients, we don't have breastfeeding safety data on file. Check with your doctor or pharmacist before using this while nursing.
Does peppermint in here actually help with digestion?
Peppermint is likely effective for irritable bowel syndrome and possibly effective for indigestion and nausea. That said, this product is branded as immune support, and the amount of peppermint may be modest—the amount in the capsule matters. If digestive relief is your main goal, a dedicated peppermint supplement might be stronger.
What's bee propolis for?
Propolis comes from honeybee hives and is possibly effective for oral mouth sores and cold sores. There's not enough evidence for other uses listed on supplement labels. If you're allergic to bee products, avoid it—allergic reactions, including severe ones, are possible.
Will this actually boost my immune system?
Vitamin C is possibly effective for some infections, and peppermint is possibly effective for nausea. For oregano, yarrow, elder flower, olive leaf, and dimethylglycine, the evidence we have isn't established yet—we don't know if they work for immune support. This isn't a proven immune booster, and marketing claims often outpace the science.
What are the most common side effects I might notice?
Peppermint can cause abdominal pain, heartburn, or belching. Vitamin C at higher doses can cause diarrhea, nausea, or headache. Bee propolis can cause headache or allergic reactions in sensitive people. Oregano and yarrow may cause digestive upset or skin irritation if applied topically. If you have stomach trouble, kidney stone history, or bee allergies, mention those to your pharmacist.

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.

Herbal Immune Support label
Go deeper

The Full Monographs Behind Herbal Immune Support’s Ingredients

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

Herb & supplement monograph

Vitamin D

Interacts with 715 drugs

Vitamin D is a fat-soluble vitamin that helps your body absorb calcium and is important for healthy bones, muscles, and immune function. Many people, especially those with low sun exposure,...

Read the full Vitamin D monograph → Herb & supplement monograph

Peppermint

Interacts with 796 drugs

Peppermint is a popular herb with the best evidence supporting enteric-coated peppermint oil for easing IBS symptoms. It is generally well tolerated for most adults, but it can cause heartbu...

Read the full Peppermint monograph → Herb & supplement monograph

Propolis

Interacts with 921 drugs

Propolis is a natural, resin-like substance made by bees that has antimicrobial and anti-inflammatory properties in lab studies. Early research suggests it may help with cold sores, mouth so...

Read the full Propolis monograph → Herb & supplement monograph

Olive

Olive comes from the same tree that gives us olives and olive oil, and its leaf and fruit contain antioxidant compounds like oleuropein and hydroxytyrosol. Olive oil as part of a Mediterrane...

Read the full Olive monograph → Herb & supplement monograph

Vitamin C

Interacts with 207 drugs

Vitamin C (ascorbic acid) is an essential nutrient your body needs but cannot make, so you must get it from food or supplements. It's important for immune function, collagen, and acts as an...

Read the full Vitamin C monograph → Herb & supplement monograph

American Elder

Interacts with 644 drugs

American elder is a North American plant whose cooked, ripe berries and flowers are used mainly for colds, flu, and general immune support. The science behind these uses is limited and most...

Read the full American Elder monograph → Herb & supplement monograph

Acerola

Interacts with 128 drugs

Acerola is a small tropical fruit prized for its very high natural vitamin C content, and it is mostly used as a food-based source of vitamin C and antioxidants. While vitamin C itself has w...

Read the full Acerola monograph → Herb & supplement monograph

Oregano

Interacts with 208 drugs

Oregano is a common Mediterranean cooking herb that is also sold as a concentrated oil or supplement, often standardized for a compound called carvacrol. While lab studies suggest it may hav...

Read the full Oregano monograph → Herb & supplement monograph

Yarrow

Interacts with 1 drug

Yarrow is a traditional herb long used for wounds, digestive complaints, and colds, but high-quality human studies are very limited, so its benefits are not well proven. It is generally used...

Read the full Yarrow monograph →
Sources

Sources & How We Checked

Herbal Immune Support'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 183 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.

Vitamin D 26 references
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  2. Tatro DS, ed. Drug Interactions Facts. Facts and Comparisons Inc., St. Louis, MO. 1999.
  3. Koutkia P, Chen TC, Holick MF. Vitamin D intoxication associated with an over-the-counter supplement. N Engl J Med 2001;345:66-7. PubMed
  4. Bar-Or D, Yoel G. Calcium and calciferol antagonize effect of verapamil in atrial fibrillation. Br Med J 1981;282:1585-6.
  5. Demontis R, Leflon A, Fournier A, et al. 1 alpha(OH) vitamin D3 increases plasma aluminum in hemodialyzed patients taking AI(OH)3. Clin Nephrol 1986;26:146-9.
  6. Crowe M, Wollner L, Griffiths RA. Hypercalcemia following vitamin D and thiazide therapy in the elderly. Practitioner 1984;228:312-3.
  7. Parfitt AM. Thiazide-induced hypercalcemia in vitamin D-treated hypoparathyroidism. Ann Intern Med 1972;77:557-63. PubMed
  8. Thiazide diuretics and the risk of osteoporosis. Pharmacist's Letter/Prescriber's Letter 2003;19(11):191105.
  9. Moon J. The role of vitamin D in toxic metal absorption. J Am Coll Nutr 1994;13:559-64.
  10. Demontis R, Reissi D, Noel C, et al. Indirect clinical evidence that 1alphaOH vitamin D<SUB>3</SUB> increases the intestinal absorption of aluminum. Clin Nephrol 1989;31:123-7.
  11. Adler AJ, Berlyne GM. Duodenal aluminum absorption in the rat: effect of vitamin D. Am J Physiol 1985;249:G209-13. PubMed
  12. Schwartz JB. Effects of vitamin D supplementation in atorvastatin-treated patients: A new drug interaction with an unexpected consequence. Clin Pharmacol Ther 2009;85:198-203. PubMed
  13. Dietary reference intakes for calcium and vitamin D. Institute of Medicine, November 30, 2010. Available at: http://www.iom.edu/~/media/Files/Report%20Files/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/Vitamin%20D%20and%20Calcium%202010%20Repo
  14. Cox KA, Dunn MA. Aluminum toxicity alters the regulation of calbindin-D28k protein and mRNA expression in chick intestine. J Nutr 2001;131:2007-13. PubMed
  15. Escribano, J., Balaguer, A., Pagone, F., Feliu, A., and Roque, I. Figuls. Pharmacological interventions for preventing complications in idiopathic hypercalciuria. Cochrane.Database.Syst.Rev. 2009;(1):CD004754. PubMed
  16. Carlton, S., Clopton, D., and Cappuzzo, K. A. Vitamin D deficiency: appropriate replenishment therapies and the effects of vitamin D toxicity. Consult Pharm 2010;25(3):171-177. PubMed
  17. Wang, H., Xia, N., Yang, Y., and Peng, D. Q. Influence of vitamin D supplementation on plasma lipid profiles: a meta-analysis of randomized controlled trials. Lipids Health Dis. 2012;11:42. PubMed
  18. Turner AN, Carr Reese P, Fields KS, Anderson J, Ervin M, Davis JA, Fichorova RN, Roberts MW, Klebanoff MA, Jackson RD. A blinded, randomized controlled trial of high-dose vitamin D supplementation to reduce recurrence of bacterial vaginosis. Am J Obstet G PubMed
  19. Weiner M, Epstein FH. Signs and symptoms of electrolyte disorders. Yale J Biol Med. 1970;43(2):76-109.
  20. Lappe J, Watson P, Travers-Gustafson D, Recker R, Garland C, Gorham E, Baggerly K, McDonnell SL. Effect of Vitamin D and Calcium Supplementation on Cancer Incidence in Older Women: A Randomized Clinical Trial. JAMA. 2017 Mar 28;317(12):1234-1243. PubMed
  21. Roth DE, Leung M, Mesfin E, Qamar H, Watterworth J, Papp E. Vitamin D supplementation during pregnancy: state of the evidence from a systematic review of randomised trials. BMJ. 2017;359:j5237. PubMed
  22. Murai IH, Fernandes AL, Sales LP, et al. Effect of a single high dose of vitamin D3 on hospital length of stay in patients with moderate to severe COVID-19: A randomized clinical trial. JAMA. 2021.
  23. Wang Z, Schuetz EG, Xu Y, Thummel KE. Interplay between vitamin D and the drug metabolizing enzyme CYP3A4. J Steroid Biochem Mol Biol 2013;136:54-8. PubMed
  24. Doyle D, Browne U, Brickley A, Murphy D. Vitamin D-induced hypercalcaemia and acute kidney injury in sarcoidosis. BMJ Case Rep 2023;16(1):e250580. PubMed
  25. Williamson A, Martineau AR, Sheikh A, Jolliffe D, Griffiths CJ. Vitamin D for the management of asthma. Cochrane Database Syst Rev 2023;2(2):CD011511. PubMed
  26. Kinesya E, Santoso D, Gde Arya N, et al. Vitamin D as adjuvant therapy for diabetic foot ulcers: Systematic review and meta-analysis approach. Clin Nutr ESPEN 2023;54:137-143. PubMed

See these in context on the Vitamin D monograph →

Peppermint 41 references
  1. Liu JH, Chen GH, Yeh HZ, et al. Enteric-coated peppermint-oil capsules in the treatment of irritable bowel syndrome: a prospective, randomized trial. J Gastroenterol 1997;32:765-8. PubMed
  2. Pittler MH, Ernst E. Peppermint oil for irritable bowel syndrome: a critical review and metaanalysis. Am J Gastroenterol 1998;93:1131-5. PubMed
  3. Kline RM, Kline JJ, Di Palma J, Barbero GJ. Enteric-coated, pH-dependent peppermint oil capsules for the treatment of irritable bowel syndrome in children. J Pediatr 2001;138:125-8. PubMed
  4. Madisch A, Heydenreich CJ, Wieland V, et al. Treatment of functional dyspepsia with a fixed peppermint oil and caraway oil combination preparation as compared to cisapride. A multicenter, reference-controlled, double-blind equivalence study. Arzneimittel
  5. May B, Kuntz HD, Kieser M, Kohler S. Efficacy of a fixed peppermint oil/caraway oil combination in non-ulcer dyspepsia. Arzneimittelforschung 1996;46:1149-53.
  6. Micklefield GH, Greving I, May B. Effects of peppermint oil and caraway oil on gastroduodenal motility. Phytother Res 2000;14:20-3. DOI
  7. Morton CA, Garioch J, Todd P, et al. Contact sensitivity to menthol and peppermint in patients with intra-oral symptoms. Contact Dermatitis 1995;32:281-4. PubMed
  8. May B, Kohler S, Schneider B. Efficacy and tolerability of a fixed combination of peppermint oil and caraway oil in patients suffering from functional dyspepsia. Aliment Pharmacol Ther 2000;14:1671-7. PubMed
  9. Nash P, Gould SR, Bernardo DE. Peppermint oil does not relieve the pain of irritable bowel syndrome. Br J Clin Pract 1986;40:292-3. DOI
  10. Rees WD, Evans BK, Rhodes J. Treating irritable bowel syndrome with peppermint oil. Br Med J 1979;2:835-6. PubMed
  11. Davies SJ, Harding LM, Baranowski AP. A novel treatment of postherpetic neuralgia using peppermint oil. Clin J Pain 2002;18:200-2. PubMed
  12. Weston CF. Anal burning and peppermint oil. Postgrad Med J 1987;63:717. PubMed
  13. Dresser GK, Wacher V, Wong S, et al. Evaluation of peppermint oil and ascorbyl palmitate as inhibitors of cytochrome P4503A4 activity in vitro and in vivo. Clin Pharmacol Ther 2002;72:247-55. PubMed
  14. Wacher VJ, Wong S, Wong HT. Peppermint oil enhances cyclosporine oral bioavailability in rats: comparison with D-alpha-tocopheryl poly(ethylene glycol 1000) succinate (TPGS) and ketoconazole. J Pharm Sci 2002;91:77-90.
  15. Lawson MJ, Knight RE, Tran K, et al. Failure of enteric-coated peppermint oil in the irritable bowel syndrome: a randomized double-blind crossover study. J Gastroenterol Hepatol 1988;3:235-8. DOI
  16. Unger M, Frank A. Simultaneous determination of the inhibitory potency of herbal extracts on the activity of six major cytochrome P450 enzymes using liquid chromatography/mass spectrometry and automated online extraction. Rapid Commun Mass Spectrom 2004;1 PubMed
  17. Maliakal PP, Wanwimolruk S. Effect of herbal teas on hepatic drug metabolizing enzymes in rats. J Pharm Pharmacol 2001;53:1323-9. PubMed
  18. Rogers SN, Pahor AL. A form of stomatitis induced by excessive peppermint consumption. Dent Update 1995;22:36-7.
  19. Cappello G, Spezzaferro M, Grossi L, et al. Peppermint oil (Mintoil) in the treatment of irritable bowel syndrome: a prospective double blind placebo-controlled randomized trial. Dig Liver Dis 2007;39:530-6. PubMed
  20. Moghadam BK, Gier R, and Thurlow T. Extensive oral mucosal ulcerations caused by misuse of a commercial mouthwash. Cutis 1999;64:131-134.
  21. Andersen, K. E. Contact allergy to toothpaste flavors. Contact Dermatitis 1978;4(4):195-198. PubMed
  22. Barnard, D. R. Repellency of essential oils to mosquitoes (Diptera: Culicidae). J Med Entomol. 1999;36(5):625-629. PubMed
  23. Tamir, S., Davidovich, Z., Attal, P., and Eliashar, R. Peppermint oil chemical burn. Otolaryngol.Head Neck Surg. 2005;133(5):801-802. PubMed
  24. Kalavala, M., Hughes, T. M., Goodwin, R. G., Anstey, A. V., and Stone, N. M. Allergic contact dermatitis to peppermint foot spray. Contact Dermatitis 2007;57(1):57-58. PubMed
  25. Vermaat, H., van Meurs, T., Rustemeyer, T., Bruynzeel, D. P., and Kirtschig, G. Vulval allergic contact dermatitis due to peppermint oil in herbal tea. Contact Dermatitis 2008;58(6):364-365. PubMed
  26. Merat, S., Khalili, S., Mostajabi, P., Ghorbani, A., Ansari, R., and Malekzadeh, R. The effect of enteric-coated, delayed-release peppermint oil on irritable bowel syndrome. Dig.Dis.Sci. 2010;55(5):1385-1390. PubMed
  27. Tran, A., Pratt, M., and DeKoven, J. Acute allergic contact dermatitis of the lips from peppermint oil in a lip balm. Dermatitis 2010;21(2):111-115. DOI
  28. Hitz, Lindenmuller, I and Lambrecht, J. T. Oral care. Curr Probl.Dermatol 2011;40:107-115.
  29. Shavakhi, A., Ardestani, S. K., Taki, M., Goli, M., and Keshteli, A. H. Premedication with peppermint oil capsules in colonoscopy: a double blind placebo-controlled randomized trial study. Acta Gastroenterol Belg 2012;75(3):349-353.
  30. Lech, Y., Olesen, K. M., Hey, H., Rask-Pedersen, E., Vilien, M., and Ostergaard, O. [Treatment of irritable bowel syndrome with peppermint oil. A double- blind study with a placebo]. Ugeskr.Laeger 10-3-1988;150(40):2388-2389.
  31. Parys, B. T. Chemical burns resulting from contact with peppermint oil mar: a case report. Burns Incl.Therm.Inj. 1983;9(5):374-375. PubMed
  32. Bayat R, Borici-Mazi R. A case of anaphylaxis to peppermint. Allergy Asthma Clin Immunol. 2014;10(1):6. PubMed
  33. Rich G, Shah A, Koloski N, et al. A randomized placebo-controlled trial on the effects of Menthacarin, a proprietary peppermint- and caraway-oil-preparation, on symptoms and quality of life in patients with functional dyspepsia. Neurogastroenterol Motil 2 PubMed
  34. Douros A, Bronder E, Andersohn F, et al. Herb-Induced Liver Injury in the Berlin Case-Control Surveillance Study. Int J Mol Sci 2016;17(1). PubMed
  35. Begas E, Tsioutsiouliti A, Kouvaras E, et al. Effects of peppermint tea consumption on the activities of CYP1A2, CYP2A6, Xanthine Oxidase, N-acetyltranferase-2 and UDP-glucuronosyltransferases-1A1/1A6 in healthy volunteers. Food Chem Toxicol 2017;100:80-9 PubMed
  36. Cash BD, Epstein MS, Shah SM. A Novel Delivery System of Peppermint Oil Is an Effective Therapy for Irritable Bowel Syndrome Symptoms. Dig Dis Sci 2016;61(2):560-71. PubMed
  37. Elsaie LT, El Mohsen AM, Ibrahim IM, Mohey-Eddin MH, Elsaie ML. Effectiveness of topical peppermint oil on symptomatic treatment of chronic pruritus. Clin Cosmet Investig Dermatol 2016;9:333-8. PubMed
  38. Wu J, Xu R, Zhan R, et al. Effective symptomatic treatment for severe and intractable pruritus associated with severe burn-induced hypertrophic scars: A prospective, multicenter, controlled trial. Burns 2016;42(5):1059-66. PubMed
  39. Weerts ZZRM, Masclee AAM, Witteman BJM, et al. Efficacy and safety of peppermint oil in a randomized, double-blind trial of patients with irritable bowel syndrome. Gastroenterology. 2020;158(1):123-136. PubMed
  40. Nee J, Ballou S, Kelley JM, et al. Peppermint Oil Treatment for Irritable Bowel Syndrome: A Randomized Placebo-Controlled Trial. Am J Gastroenterol 2021;116(11):2279-2285. PubMed
  41. Ingrosso MR, Ianiro G, Nee J, et al. Systematic review and meta-analysis: efficacy of peppermint oil in irritable bowel syndrome. Aliment Pharmacol Ther 2022;56(6):932-41. PubMed

See these in context on the Peppermint monograph →

Propolis 21 references
  1. Hay KD, Greig DE. Propolis allergy: a cause of oral mucositis with ulceration. Oral Surg Oral Med Oral Pathol 1990;70:584-6. PubMed
  2. Li YJ, Lin JL, Yang CW, Yu CC. Acute renal failure induced by a Brazilian variety of propolis. Am J Kidney Dis 2005;46:e125-9. PubMed
  3. Jensen CD, Andersen KE. Allergic contact dermatitis from cera alba (purified propolis) in a lip balm and candy. Contact Dermatitis 2006;55:312-3. PubMed
  4. Chen, T. G., Lee, J. J., Lin, K. H., Shen, C. H., Chou, D. S., and Sheu, J. R. Antiplatelet activity of caffeic acid phenethyl ester is mediated through a cyclic GMP-dependent pathway in human platelets. Chin J Physiol 6-30-2007;50(3):121-126.
  5. Hsu, C. Y., Chiang, W. C., Weng, T. I., Chen, W. J., and Yuan, A. Laryngeal edema and anaphalactic shock after topical propolis use for acute pharyngitis. Am J Emerg.Med 2004;22(5):432-433. PubMed
  6. Black, R. J. Vulval eczema associated with propolis sensitization from topical therapies treated successfully with pimecrolimus cream. Clin Exp.Dermatol. 2005;30(1):91-92. PubMed
  7. Matos D, Serrano P, Brandao FM. A case of allergic contact dermatitis caused by propolis-enriched honey. Contact Dermatitis 2015;72(1):59-60. PubMed
  8. Naramoto K, Kato M, Ichihara K. Effects of an ethanol extract of Brazilian green propolis on human cytochrome P450 enzyme activities in vitro. J Agric Food Chem 2014;62(46):11296-302. PubMed
  9. Nyman G, Hagvall L. A case of allergic contact cheilitis caused by propolis and honey. Contact Dermatitis 2016;74(3):186-7. PubMed
  10. Ryu CS, Oh SJ, Oh JM, et al. Inhibition of cytochrome P450 by propolis in human liver microsomes. Toxicol Res 2016;32(3):207-13. PubMed
  11. Akbay E, Özenirler Ç, Çelemli ÖG, Durukan AB, Onur MA, Sorkun K. Effects of propolis on warfarin efficacy. Kardiochir Torakochirurgia Pol. 2017;14(1):43-46. PubMed
  12. Lamoureux A, Meharon M, Durand AL, Darrigade AS, Doutre MS, Milpied B. A first case of erythema multiforme-like contact dermatitis caused by propolis. Contact Dermatitis. 2017;77(4):263-264. PubMed
  13. Piredda M, Facchinetti G, Biagioli V, et al. Propolis in the prevention of oral mucositis in breast cancer patients receiving adjuvant chemotherapy: A pilot randomised controlled trial. Eur J Cancer Care (Engl). 2017;26(6). PubMed
  14. Zhang YX, Yang TT, Xia L, Zhang WF, Wang JF, Wu YP. Inhibitory Effect of Propolis on Platelet Aggregation In Vitro. J Healthc Eng. 2017;2017:3050895. PubMed
  15. Nyman GSA, Tang M, Inerot A, Osmancevic A, Malmberg P, Hagvall L. Contact allergy to beeswax and propolis among patients with cheilitis or facial dermatitis. Contact Dermatitis 2019;81(2):110-6. PubMed
  16. Igarashi G, Segawa T, Akiyama N, et al. Efficacy of Brazilian propolis supplementation for japanese lactating women for atopic sensitization and nonspecific symptoms in their offspring: a randomized, double-blind, placebo-controlled trial. Evid Based Comp PubMed
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Olive 2 references
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See these in context on the Olive monograph →

Vitamin C 51 references
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  14. Smith EC, Skalski RJ, Johnson GC, Rossi GV. Interaction of ascorbic acid and warfarin. JAMA 1972;221:1166. DOI
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  17. Domingo JL, Gomez M, Llobet JM, Corbella J. Influence of some dietary constituents on aluminum absorption and retention in rats. Kidney Int 1991;39:598-601. PubMed
  18. Partridge NA, Regnier FE, White JL, Hem SL. Influence of dietary constituents on intestinal absorption of aluminum. Kidney Int 1989;35:1413-7. PubMed
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  34. Rahimi, R., Nikfar, S., Rezaie, A., and Abdollahi, M. A meta-analysis on the efficacy and safety of combined vitamin C and E supplementation in preeclamptic women. Hypertens.Pregnancy. 2009;28(4):417-434. PubMed
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  36. Li, G., Li, L., Yu, C., and Chen, L. Effect of vitamins C and E supplementation on Helicobacter pylori eradication: a meta-analysis. Br.J Nutr 2011;106(11):1632-1637.
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  51. Pejcic AV, Petrovic NZ, Djordjic MD, Milosavljevic MN. Vitamin C Levels in Pregnant Women and the Efficacy of Vitamin C Supplements in Preventing Premature Rupture of Membranes: A Systematic Review and Meta-Analysis. Balkan Med J 2024;41(4):248-260. PubMed

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American Elder 2 references
  1. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  2. Budzinski JW, Foster BC, Vandenhoek S, Arnason JT. An in vitro evaluation of human cytochrome P450 3A4 inhibition by selected commercial herbal extracts and tinctures. Phytomedicine 2000;7:273-82. PubMed

See these in context on the American Elder monograph →

Acerola 20 references
  1. Back DJ, Breckenridge AM, MacIver M, et al. Interaction of ethinyloestradiol with ascorbic acid in man. Br Med J (Clin Res Ed) 1981;282:1516.
  2. Morris JC, Beeley L, Ballantine N. Interaction of ethinyloestradiol with ascorbic acid in man [letter]. Br Med J (Clin Res Ed) 1981;283:503.
  3. Labriola D, Livingston R. Possible interactions between dietary antioxidants and chemotherapy. Oncology 1999;13:1003-8.
  4. Hansten PD, Horn JR. Drug Interactions Analysis and Management. Vancouver, WA: Applied Therapeutics Inc., 1997 and updates.
  5. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: National Academy Press, 2000. Available at: http://www.nap.edu/books/0309069351/html/.
  6. Rosenthal G. Interaction of ascorbic acid and warfarin. JAMA 1971;215:1671. DOI
  7. Hume R, Johnstone JM, Weyers E. Interaction of ascorbic acid and warfarin. JAMA 1972;219:1479. DOI
  8. Smith EC, Skalski RJ, Johnson GC, Rossi GV. Interaction of ascorbic acid and warfarin. JAMA 1972;221:1166. DOI
  9. Domingo JL, Gomez M, Llobet JM, Richart C. Effect of ascorbic acid on gastrointestinal aluminum absorption (letter). Lancet 1991;338:1467.
  10. Domingo JL, Gomez M, Llobet JM, Corbella J. Influence of some dietary constituents on aluminum absorption and retention in rats. Kidney Int 1991;39:598-601. PubMed
  11. Partridge NA, Regnier FE, White JL, Hem SL. Influence of dietary constituents on intestinal absorption of aluminum. Kidney Int 1989;35:1413-7. PubMed
  12. Mc Leod DC, Nahata MC. Inefficacy of ascorbic acid as a urinary acidifier (letter). N Engl J Med 1977;296:1413. DOI
  13. Hansten PD, Hayton WL. Effect of antacid and ascorbic acid on serum salicylate concentration. J Clin Pharmacol 1980;20:326-31. PubMed
  14. Vihtamaki T, Parantainen J, Koivisto AM, et al. Oral ascorbic acid increases plasma oestradiol during postmenopausal hormone replacement therapy. Maturitas 2002;42:129-35. PubMed
  15. Feetam CL, Leach RH, Meynell MJ. Lack of a clinically important interaction between warfarin and ascorbic acid. Toxicol Appl Pharmacol 1975;31:544-7. PubMed
  16. Weintraub M, Griner PF. Warfarin and ascorbic acid: lack of evidence for a drug interaction. Toxicol Appl Pharmacol 1974;28:53-6. PubMed
  17. Prasad KN. Rationale for using high-dose multiple dietary antioxidants as an adjunct to radiation therapy and chemotherapy. J Nutr 2004;134:3182S-3S. PubMed
  18. Conklin KA. Cancer chemotherapy and antioxidants. J Nutr 2004;134:3201S-3204S. PubMed
  19. Denadai R, Souza FM, Valle MR. Fecal impaction by rectal acerola bezoar. Indian J Pediatr 2013;80(5):432-3. PubMed
  20. Raulf-Heimsoth M, Stark R, Sander I, et al. Anaphylactic reaction to apple juice containing acerola: cross-reactivity to latex due to prohevein. J Allergy Clin Immunol 2002;109(4):715-6. PubMed

See these in context on the Acerola monograph →

Oregano 12 references
  1. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  2. Benito M, Jorro G, Morales C, et al. Labiatae allergy: systemic reactions due to ingestion of oregano and thyme. Ann Allergy Asthma Immunol 1996;76:416-8. PubMed
  3. Chevallier A. Encyclopedia of Herbal Medicine. 2nd ed. New York, NY: DK Publ, Inc., 2000.
  4. Ciganda C, and Laborde A. Herbal infusions used for induced abortion. J Toxicol.Clin Toxicol. 2003;41:235-239. PubMed
  5. Futrell, J. M. and Rietschel, R. L. Spice allergy evaluated by results of patch tests. Cutis 1993;52(5):288-290.
  6. Tognolini, M., Barocelli, E., Ballabeni, V., Bruni, R., Bianchi, A., Chiavarini, M., and Impicciatore, M. Comparative screening of plant essential oils: phenylpropanoid moiety as basic core for antiplatelet activity. Life Sci. 2-23-2006;78(13):1419-1432. PubMed
  7. Goun, E., Cunningham, G., Solodnikov, S., Krasnykch, O., and Miles, H. Antithrombin activity of some constituents from Origanum vulgare. Fitoterapia 2002;73(7-8):692-694. PubMed
  8. Lemhadri, A., Zeggwagh, N. A., Maghrani, M., Jouad, H., and Eddouks, M. Anti-hyperglycaemic activity of the aqueous extract of Origanum vulgare growing wild in Tafilalet region. J Ethnopharmacol. 2004;92(2-3):251-256. PubMed
  9. McCue, P., Vattem, D., and Shetty, K. Inhibitory effect of clonal oregano extracts against porcine pancreatic amylase in vitro. Asia Pac.J Clin.Nutr. 2004;13(4):401-408.
  10. Ragi, J., Pappert, A., Rao, B., Havkin-Frenkel, D., and Milgraum, S. Oregano extract ointment for wound healing: a randomized, double-blind, petrolatum-controlled study evaluating efficacy. J.Drugs Dermatol. 2011;10(10):1168-1172.
  11. Singletary K. Oregano: overview of the literature on health benefits. Nutrition Today 2010;45(3):129-38.
  12. Silva MLAE, Lucarini R, Dos Santos FF, et al. Hypoglycemic effect of rosmarinic acid-rich infusion (RosCE) from Origanum vulgare in alloxan-induced diabetic rats. Nat Prod Res 2022;36(17):4525-4531.

See these in context on the Oregano monograph →

Yarrow 8 references
  1. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  2. Uter, W., Nohle, M., Randerath, B., and Schwanitz, H. J. Occupational contact urticaria and late-phase bronchial asthma caused by compositae pollen in a florist. Am J Contact Dermat. 2001;12(3):182-184. DOI
  3. Schempp, C. M., Schopf, E., and Simon, J. C. [Plant-induced toxic and allergic dermatitis (phytodermatitis)]. Hautarzt 2002;53(2):93-97.
  4. Jovanovic, M., Poljacki, M., Duran, V., Vujanovic, L., Sente, R., and Stojanovic, S. Contact allergy to Compositae plants in patients with atopic dermatitis. Med Pregl. 2004;57(5-6):209-218. PubMed
  5. Becker LC, Bergfeld WF, Belsito DV, et al. Safety assessment of Achillea millefolium as used in cosmetics. Int J Toxicol. 2016;35(3 suppl):5S-15S.
  6. Zakeri S, Esmaeilzadeh S, Gorji N, Memariani Z, Moeini R, Bijani A. The effect of Achillea millefolium L. on vulvovaginal candidiasis compared with clotrimazole: A randomized controlled trial. Complement Ther Med. 2020;52:102483. PubMed
  7. de Souza P, Crestani S, da Silva Rde C, et al. Involvement of bradykinin and prostaglandins in the diuretic effects of Achillea millefolium L. (Asteraceae). J Ethnopharmacol. 2013 Aug 26;149(1):157-61. PubMed
  8. Miranzadeh S, Adib-Hajbaghery M, Soleymanpoor L, Ehsani M. Effect of adding the herb Achillea millefolium on mouthwash on chemotherapy induced oral mucositis in cancer patients: A double-blind randomized controlled trial. Eur J Oncol Nurs. 2015;19(3):207- PubMed

See these in context on the Yarrow monograph →

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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.

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