Major interaction on record — check this product against your medications before combining. Check your meds →
Dietary supplement

ViraGuard Ingredients & Drug Interactions

by Equip

ViraGuard label
See full label image
Capsule Category: Other Combinations
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 30, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking ViraGuard 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

ViraGuard is a dietary supplement by Equip with 10 active ingredients. Its ingredients are commonly taken for diabetic nerve pain (neuropathy), blood sugar support in diabetes, antioxidant support.Based on those ingredients, 1,488 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Licorice (Glycyrrhiza glabra) root extract, Grape seed (Vitis vinifera) seed extract, Vitamin D. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against ViraGuard by Equip

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

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HelloPharmacist Scorecard of ViraGuard by Equip

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 Sep 24, 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.

ViraGuard contains 10 active ingredients: alpha-lipoic acid (an antioxidant), vitamins A, C, and D (micronutrients), zinc (a mineral), N-acetyl cysteine (an amino acid derivative), licorice root extract (an herbal), selenium (a mineral), copper (a mineral), and grape seed extract (an herbal). Together they're meant to support immune function and antioxidant defense.

The capsule also contains microcrystalline cellulose, hydroxypropyl methylcellulose, and L-leucine as inactive ingredients.

Does it work?

Not established
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
Not established

The graded evidence we hold for these ingredients covers different conditions than the ones this product is marketed for, so there's no established rating for its stated use.

Why this rating?
  • The label markets this product for: immune system support and defense.
  • We looked for evidence on: Immune function, Infection prevention, Viral defense.
  • The closest evidence on file: Vitamin A is rated "Possibly Ineffective" for Intestinal parasite infection (Natural Medicines).
  • Also on file: Copper is rated "Insufficient Reliable Evidence To Rate" for Postoperative infection.
  • Also on file: Vitamin D is rated "Insufficient Reliable Evidence To Rate" for Upper respiratory tract infection (URTI), Fall prevention.

The evidence for these ingredients is mixed. Alpha-lipoic acid is possibly effective for diabetic nerve pain and high cholesterol; vitamin A is effective for vitamin A deficiency and possibly effective for oral leukoplakia and measles; vitamin C is effective for vitamin C deficiency and possibly effective for anemia and infection prevention after exercise.

Vitamin D is effective for rickets and renal bone disease. Zinc is effective for zinc deficiency and possibly effective for age-related macular degeneration and acne.

N-acetyl cysteine is effective for acetaminophen poisoning and possibly effective for bronchitis. Licorice is possibly effective for eczema and canker sores.

Selenium is likely effective for selenium deficiency and possibly effective for autoimmune thyroiditis. Copper is likely effective for copper deficiency.

Grape seed extract is possibly effective for chronic venous insufficiency (poor circulation in the legs). No single ingredient in this product has been studied specifically to prevent viral infection; we have no effectiveness data on file for ViraGuard as a whole.

The evidence, ingredient by ingredient Alpha-lipoic Acid Vitamin A Vitamin C Vitamin D Zinc N-acetyl Cysteine (nac) Licorice Selenium

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 10 of the 10 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 10 of 10.
  • General safety write-ups exist for 10 of 10.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

These ingredients are generally well tolerated at typical doses, but some carry cautions. Alpha-lipoic acid can lower blood sugar and is best used under medical guidance; it's not recommended in pregnancy or while breastfeeding.

Vitamin A is safe at recommended amounts but high doses can be toxic and cause birth defects—avoid high-dose supplements in pregnancy or breastfeeding. Vitamin C is generally safe but high doses can cause kidney stones and other side effects; avoid high-dose supplements in pregnancy or breastfeeding.

Vitamin D is safe at recommended doses but very high doses can cause toxicity; use only under medical guidance in pregnancy. Zinc is safe in recommended amounts; high doses may cause nausea and diarrhea and carry theoretical risk of copper deficiency over time.

N-acetyl cysteine is generally well tolerated but discuss with your doctor before use; safety during pregnancy has not been well studied. Licorice should be avoided in pregnancy and breastfeeding due to potential harm.

Selenium is safe in recommended amounts but excess can cause hair loss, nail problems, and fatigue; avoid high doses unless advised by your doctor. Copper is safe in food and standard supplements; avoid high-dose supplements in pregnancy or breastfeeding unless advised.

Grape seed extract appears well tolerated; grapes as food are fine in pregnancy, but concentrated supplements should be avoided due to limited safety data.

Side effects, ingredient by ingredient Alpha-lipoic Acid Vitamin A Vitamin C Vitamin D Zinc N-acetyl Cysteine (nac) Licorice Selenium

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?
  • 10 of the 10 matched ingredients can interact with medications — Grape, Alpha-lipoic Acid, Licorice, Copper, Vitamin D, among others.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; immunosuppressants / transplant drugs; cancer treatments; diabetes medications; heart-rhythm medications.
  • For scale: 1,489 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 ViraGuard, double-check with your pharmacist if you take nitroglycerin (N-acetyl cysteine raises bleeding and low-blood-pressure risk—Major severity). Also flag it if you use blood thinners or antiplatelet drugs like warfarin or aspirin, heart medications like verapamil or digoxin, antibiotics (especially quinolones, tetracyclines, or cephalexin), chemotherapy drugs, HIV medications, thyroid medication, or diabetes drugs.

These are the main medication types affected by ingredients in this product.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with no established evidence rating for its marketed use. Major medication interactions have been identified, and safety information is well characterized.

ViraGuard is a multi-ingredient supplement with mixed evidence—some components have established roles for specific conditions like vitamin A deficiency or zinc deficiency, while others like the viral-support claim lack solid data in our files. If you take blood thinners, heart medications, antibiotics, chemotherapy, or HIV drugs, you need to check this product carefully before starting.

Talk it over with your doctor or pharmacist, especially if you're pregnant, breastfeeding, or have diabetes or heart issues.

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

Assessment coverage: 10 of 10 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Aug 23, 2021.

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 ViraGuard, straight from the product label.

Brand Equip
Barcode (UPC) 810031710270
Net contents 60 Capsule(s)
Market status On market
Date entered into DSLD Aug 23, 2021
DSLD ID 248438
Product type Other Combinations
Supplement form Capsule
Dietary claims / uses Nutrient, 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 ViraGuard by Equip, 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 Vegetarian Capsule(s)
Maximum serving Sizes:
2 Vegetarian Capsule(s)
Servings per container
30
UPC/BARCODE
810031710270
IngredientAmount% DV
Alpha Lipoic Acid100 mg--
Vitamin A900 mcg RAE100%
Vitamin C200 mg222%
Vitamin D50 mcg250%
Zinc20 mg182%
N-Acetyl-L-Cysteine300 mg--
Licorice (Glycyrrhiza glabra) root extract100 mg--
Selenium400 mcg727%
Copper1 mg111%
Grape seed (Vitis vinifera) seed extract30 mg--

Other ingredients: Microcrystalline Cellulose, Hydroxypropyl Methylcellulose, L-Leucine

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

Feed What You Need

Formulation

Your body needs a lot of raw materials to fight the invisible monsters you come across. These nutrients are found in real foods that people don't eat. We use the purest forms in the ideal amounts in ViraGuard to help arm your immune system for the never ending fight.

Daily real food Nutrient immunity Defense

FDA Disclaimer Statement

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent disease.

Seals/Symbols

100% Paleo Friendly

FDA Statement of Identity

Dietary Supplement

Suggested/Recommended/Usage/Directions

How to use: For general immune support, take one to two servings daily.

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

See for yourself

ViraGuard by Equip label

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

ViraGuard 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 ViraGuard by Equip

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

Serving size2 Vegetarian 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.

Alpha Lipoic Acid

Interacts with
263 drugs
100 mg per serving

Alpha-lipoic acid (ALA) is an antioxidant made naturally by the body and found in small amounts in foods. It is most studied for diabetic nerve pain,...

Alpha Lipoic Acid monograph & interactions

Vitamin A

Interacts with
387 drugs
900 mcg RAE per serving Form: Beta-Carotene

Vitamin A is an essential nutrient important for vision, skin, immune function, and growth. Most people get enough from a balanced diet, and supplemen...

Vitamin A monograph & interactions

Vitamin C

Interacts with
207 drugs
200 mg per serving Form: Ascorbic Acid

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

Vitamin D

Interacts with
715 drugs
50 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 D monograph & interactions

Zinc

Interacts with
67 drugs
20 mg per serving Form: Zinc Citrate

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

N-Acetyl-L-Cysteine

Interacts with
294 drugs
300 mg per serving

N-acetyl cysteine (NAC) is a supplement form of the amino acid cysteine and a building block for the antioxidant glutathione. It has well-established...

N-Acetyl-L-Cysteine monograph & interactions

Licorice (Glycyrrhiza glabra) root extract

Interacts with
1,040 drugs
100 mg per serving

Licorice root is a traditional remedy used for sore throats, coughs, and digestive complaints, but solid human evidence is limited for most uses. Regu...

Licorice (Glycyrrhiza glabra) root extract monograph & interactions

Selenium

Interacts with
321 drugs
400 mcg per serving Form: Selenium Chelate

Selenium is an essential trace mineral your body needs in small amounts for thyroid function, antioxidant defense, and immune health. Most people who...

Selenium monograph & interactions

Copper

Interacts with
31 drugs
1 mg per serving Form: Copper Citrate

Copper is an essential trace mineral your body needs in small amounts for making red blood cells, supporting nerves and bones, and helping enzymes wor...

Copper monograph & interactions

Grape seed (Vitis vinifera) seed extract

Interacts with
910 drugs
30 mg per serving

Grapes and grape products like grape seed extract contain antioxidant compounds such as resveratrol and proanthocyanidins that may support heart and b...

Grape seed (Vitis vinifera) seed extract monograph & interactions

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

Interaction report

ViraGuard by Equip Drug Interactions

Want to check YOUR meds against ViraGuard?

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
1,488Drugs
10 Major 1,411 Moderate 67 Minor

Ingredients driving the most interactions

Licorice (Glycyrrhiza glabra) root extract 1,040
Grape seed (Vitis vinifera) seed extract 910
Vitamin D 715
Vitamin A 387
Selenium 321

Individual Drug Interactions

The ingredients in ViraGuard interact with 1,488 drugs. Click any drug to see the details.

10 of the 10 ingredients in ViraGuard interact with drugs. Each result below shows which ingredient is responsible. Licorice (Glycyrrhiza glabra) root extract Grape seed (Vitis vinifera) seed extract Vitamin D Vitamin A Selenium N-Acetyl-L-Cysteine Alpha Lipoic Acid Vitamin C Zinc Copper

Each ingredient & the kinds of drugs it affects

For each ingredient in ViraGuard 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.

Licorice (Glycyrrhiza glabra) root extract18 drug types · 1,040 drugs

Antihypertensive Drugs

Theoretically, licorice might reduce the effects of antihypertensive drugs.
In human research, licorice increases blood pressure in a dose-dependent manner.

Likelihood Possible Evidence B
Cisplatin (Platinol-Aq)

Theoretically, licorice might reduce the effects of cisplatin.
In animal research, licorice diminished the therapeutic efficacy of cisplatin.

Likelihood Possible Evidence D
Corticosteroids

Theoretically, concomitant use of licorice and corticosteroids might increase the side effects of corticosteroids.
Case reports suggest that concomitant use of licorice and oral corticosteroids, such as hydrocortisone, can potentiate the duration of activity and increase blood levels of corticosteroids. Additionally, in one case report, a patient with neurogenic orthostatic hypertension stabilized on fludrocortisone 0.1 mg twice daily developed pseudohyperaldosteronism after recent consumption of large amounts of black licorice.

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

Theoretically, licorice might increase levels of drugs metabolized by CYP2B6.
In vitro research shows that licorice extract and glabridin, a licorice constituent, inhibit CYP2B6 isoenzymes. Licorice extract from the species G. uralensis seems to inhibit CYP2B6 isoenzymes to a greater degree than G. glabra extract in vitro. Theoretically, these species of licorice might increase levels of drugs metabolized by CYP2B6; however, these interactions have not yet been reported in humans.

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

Theoretically, licorice might increase levels of drugs metabolized by CYP2C19.
In vitro, licorice extracts from the species G. glabra and G. uralensis inhibit CYP2C19 isoenzymes in vitro. Theoretically, these species of licorice might increase levels of drugs metabolized by CYP2C19; however, this interaction has not yet been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2C8 (Cyp2C8) Substrates

Theoretically, licorice might increase levels of drugs metabolized by CYP2C8.
In vitro, licorice extract from the species G. glabra and G. uralensis inhibits CYP2C8 isoenzymes. Theoretically, these species of licorice might increase levels of drugs metabolized by CYP2C8; however, this interaction has not yet been reported in humans.

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

Theoretically, licorice might increase or decrease levels of drugs metabolized by CYP2C9.
There is conflicting evidence about the effect of licorice on CYP2C9 enzyme activity. In vitro research shows that extracts from the licorice species G. glabra and G. uralensis moderately inhibit CYP2C9 isoenzymes. However, evidence from an animal model shows that licorice extract from the species G. uralensis can induce hepatic CYP2C9 activity. Until more is known, licorice should be used cautiously in people taking CYP2C9 substrates.

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

Theoretically, licorice might increase or decrease levels of drugs metabolized by CYP3A4.
Pharmacokinetic research shows that the licorice constituent glycyrrhizin, taken in a dosage of 150 mg orally twice daily for 14 days, modestly decreases the area under the concentration-time curve of midazolam by about 20%. Midazolam is a substrate of CYP3A4, suggesting that glycyrrhizin modestly induces CYP3A4 activity. Animal research also shows that licorice extract from the species G. uralensis induces CYP3A4 activity. However, licorice extract from G. glabra species appear to inhibit CYP3A4-induced metabolism of testosterone in vitro. It is thought that the G. glabra inhibits CYP3A4 due to its constituent glabridin, which is a moderate CYP3A4 inhibitor in vitro and not present in other licorice species. Until more is known, licorice should be used cautiously in people taking CYP3A4 substrates.

Likelihood Possible Evidence B
Digoxin (Lanoxin)

Theoretically, concomitant use of licorice with digoxin might increase the risk of cardiac toxicity.
Overuse or misuse of licorice with cardiac glycoside therapy might increase the risk of cardiac toxicity due to potassium loss.

Likelihood Possible Evidence D
Diuretic Drugs

Theoretically, concomitant use of licorice with diuretic drugs might increase the risk of hypokalemia.
Overuse of licorice might compound diuretic-induced potassium loss. In one case report, a 72-year-old male with a past medical history of hypertension, type 2 diabetes, hyperlipidemia, arrhythmia, stroke, and hepatic dysfunction was hospitalized with severe hypokalemia and uncontrolled hypertension due to pseudohyperaldosteronism. This was thought to be provoked by concomitant daily consumption of a product containing 225 mg of glycyrrhizin, a constituent of licorice, and hydrochlorothiazide 12.5 mg for 1 month.

Likelihood Possible Evidence D
Estrogens

Theoretically, licorice might increase or decrease the effects of estrogen therapy.
Theoretically, licorice might interfere with estrogen therapy due to estrogenic and anti-estrogenic effects.

Likelihood Possible Evidence D
Loop Diuretics

Theoretically, loop diuretics might increase the mineralocorticoid effects of licorice.
Theoretically, loop diuretics might enhance the mineralocorticoid effects of licorice by inhibiting the enzyme that converts cortisol to cortisone; however, bumetanide (Bumex) does not appear to have this effect.

Likelihood Possible Evidence D
Midazolam (Versed)

Theoretically, licorice might decrease levels of midazolam.
In humans, the licorice constituent glycyrrhizin appears to moderately induce the metabolism of midazolam. This is likely due to induction of cytochrome P450 3A4 by licorice. Until more is known, licorice should be used cautiously in people taking midazolam.

Likelihood Possible Evidence B
P-Glycoprotein Substrates

Theoretically, licorice might decrease the absorption of P-glycoprotein substrates.
In vitro research shows that licorice can increase P-glycoprotein activity.

Likelihood Possible Evidence D
Paclitaxel (Abraxane, Onxol)

Theoretically, licorice might decrease plasma levels and clinical effects of paclitaxel.
Multiple doses of licorice taken concomitantly with paclitaxel might reduce the effectiveness of paclitaxel. Animal research shows that licorice 3 grams/kg given orally for 14 days before intravenous administration of paclitaxel decreases the exposure to paclitaxel and increases its clearance. Theoretically, this occurs because licorice induces cytochrome P450 3A4 enzymes, which metabolize paclitaxel. Notably, a single dose of licorice did not affect exposure or clearance of paclitaxel.

Likelihood Possible Evidence D
Warfarin (Coumadin)

Theoretically, licorice might decrease plasma levels and clinical effects of warfarin.
Licorice seems to increase metabolism and decrease levels of warfarin in animal models. This is likely due to induction of cytochrome P450 2C9 (CYP2C9) metabolism by licorice. Advise patients taking warfarin to avoid taking licorice.

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

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

Likelihood Possible Evidence D
Methotrexate (Trexall, Others)

Theoretically, licorice might increase levels of methotrexate.
Animal research suggests that intravenous administration of glycyrrhizin, a licorice constituent, and high-dose methotrexate may delay methotrexate excretion and increase systemic exposure, leading to transient elevations in liver enzymes and total bilirubin. This interaction has not yet been reported in humans.

Likelihood Unlikely Evidence D
Licorice (Glycyrrhiza glabra) root extract full monograph & interactions

Grape seed (Vitis vinifera) seed extract9 drug types · 910 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, grape extracts may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
In vitro evidence suggests that grape extracts might decrease platelet aggregation.

Likelihood Possible Evidence D
Cyclosporine (Neoral, Sandimmune)

Ingesting grape juice with cyclosporine can reduce cyclosporine absorption.
A small pharmacokinetic study in healthy young adults shows that intake of purple grape juice 200 mL along with cyclosporine can decrease the absorption of cyclosporine by up to 30% when compared with water. Separate doses of grape juice and cyclosporine by at least 2 hours to avoid this interaction.

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

Theoretically, grape juice might reduce the levels of CYP1A2 substrates.
A small pharmacokinetic study in healthy adults shows that ingestion of 200 mL of grape juice decreases phenacetin plasma levels. This is thought to be due to induction of CYP1A2.

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

Theoretically, grape seed extract may increase the levels of CYP2D6 substrates.
In vitro evidence suggests that grape seed extract might inhibit CYP2D6 enzymes. However, this interaction has not been reported in humans.

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

Theoretically, grape seed extract might increase the levels of CYP2E1 substrates.
In vitro and animal research suggests that grape seed proanthocyanidin extract inhibits CYP2E1 enzymes. However, this interaction has not been reported in humans.

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

It is unclear if grape seed extract inhibits or induces CYP3A4; research is conflicting.
In vitro evidence suggests that grape seed extract might inhibit CYP3A4 enzymes. However, evidence from animal research shows that grape seed extract may induce CYP3A4 in the liver. So far, these interactions have not been reported in humans.

Likelihood Possible Evidence D
Midazolam (Versed)

Theoretically, long-term intake of grape seed extract might decrease the effects of midazolam.
Animal research shows that subchronic ingestions of grape seed extract can increase the elimination of intravenous midazolam by increasing hepatic CYP3A4 activity. Single doses of grape seed extract do not appear to affect midazolam elimination.

Likelihood Possible Evidence D
Phenacetin

Grape juice might decrease phenacetin absorption.
A small pharmacokinetic study in healthy adults shows that ingestion of 200 mL of grape juice decreases phenacetin plasma levels. This is thought to be due to induction of cytochrome P450 1A2 (CYP1A2).

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

It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
In vitro evidence shows that grape seed extract or grape juice might inhibit CYP2C9 enzymes. However, a small pharmacokinetic study in healthy adults shows that drinking 8 ounces of grape juice once does not affect the clearance of flurbiprofen, a probe-drug for CYP2C9 metabolism. The effects of continued grape juice consumption are unclear.

Likelihood Unlikely Evidence D
Grape seed (Vitis vinifera) seed extract full monograph & interactions

Vitamin D8 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 D full monograph & interactions

Vitamin A4 drug types · 387 drugs

Retinoids

Concomitant use of retinoids with vitamin A supplements might produce supratherapeutic vitamin A levels.
Retinoids, which are vitamin A derivatives, could have additive toxic effects when taken with vitamin A supplements.

Likelihood Probable Evidence D
Hepatotoxic Drugs

Theoretically, taking high doses of vitamin A in combination with other potentially hepatotoxic drugs might increase the risk of liver disease.
The tolerable upper intake level (UL) is the highest level of intake that is likely to pose no risk of adverse effects. Doses of vitamin A above the UL can cause hepatotoxicity, ranging from elevated liver enzymes to liver failure.

Likelihood Possible Evidence C
Tetracycline Antibiotics

Theoretically, taking tetracycline antibiotics with high doses of vitamin A can increase the risk of pseudotumor cerebri.
Benign intracranial hypertension (pseudotumor cerebri) can occur with tetracyclines and with acute or chronic vitamin A toxicity. Case reports suggest that taking tetracyclines and vitamin A concurrently can increase the risk of this condition. Avoid high doses of vitamin A in people taking tetracyclines chronically.

Likelihood Possible Evidence D
Warfarin (Coumadin)

Theoretically, high doses of vitamin A could increase the risk of bleeding with warfarin.
Vitamin A toxicity is associated with hemorrhage and hypoprothrombinemia, possibly due to vitamin K antagonism. Advise patients taking warfarin to avoid doses of vitamin A above the tolerable upper intake level of 10,000 IU/day for adults.

Likelihood Possible Evidence D
Vitamin A full monograph & interactions

Selenium6 drug types · 321 drugs

Anticoagulant/Antiplatelet Drugs

Selenium may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
Clinical research suggests that taking selenium 10 mcg/kg/day can increase bleeding times by increasing prostacyclin production, which inhibits platelet activity. Other clinical research suggests that taking selenium 75 mcg daily, in combination with ascorbic acid 600 mg, alpha-tocopherol 300 mg, and beta-carotene 27 mg, reduces platelet aggregation.

Likelihood Possible Evidence D
Barbiturates

Theoretically, selenium might prolong the sedating effects of barbiturates.
Laboratory research suggests that selenium can inhibit the hepatic metabolism of barbiturates. Selenium seems to prolong the sedative effect of pentobarbital in animal models.

Likelihood Possible Evidence D
Immunosuppressants

Theoretically, selenium supplementation may reduce the effectiveness of immunosuppressant therapy.
In vitro research and preliminary clinical evidence suggests that selenium may stimulate the immune system.

Likelihood Possible Evidence D
Warfarin (Coumadin)

Theoretically, selenium might interfere with warfarin activity.
Animal research suggests that selenium can increase warfarin activity. Selenium might interact with warfarin by displacing it from albumin binding sites, reducing its metabolism in the liver, or by decreasing production of vitamin K-dependent clotting factors. Selenium can also prolong bleeding times in humans by increasing prostacyclin production, which inhibits platelet activity.

Likelihood Possible Evidence D
Contraceptive Drugs

Contraceptive drugs might increase levels of selenium, although the clinical significance of this effect is unclear.
Some research suggests that oral contraceptives increase serum selenium levels in women taking oral contraceptives; however, other research shows no change in selenium levels. It is suggested that an increase could be due to increased carrier proteins, indicating a redistribution of selenium rather than a change in total body selenium.

Likelihood Possible Evidence B
Niacin

Selenium might reduce the beneficial effects of niacin on high-density lipoprotein (HDL) 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 selenium, or to the combination. It also is not known whether it will occur in other patient populations.

Likelihood Possible Evidence A
Selenium full monograph & interactions

N-Acetyl-L-Cysteine5 drug types · 294 drugs

Nitroglycerin

N-acetyl cysteine can increase the risk for hypotension and headaches when taken with intravenous or transdermal nitroglycerin.
Clinical research shows that concomitant administration of N-acetyl cysteine and intravenous or transdermal nitroglycerin can cause severe hypotension and intolerable headaches. Furthermore, in vitro research suggests that N-acetyl cysteine increases the anticoagulant activity of nitroglycerin.

Likelihood Probable Evidence B
Activated Charcoal

N-acetyl cysteine might reduce the effects of activated charcoal, while activated charcoal might reduce the absorption of N-acetyl cysteine.
N-acetyl cysteine appears to reduce the capacity of activated charcoal to adsorb acetaminophen and salicylic acid. Conversely, although clinical research suggests that although activated charcoal can reduce the absorption of N-acetyl cysteine by up to 40%, it does not seem to reduce its clinical effects. Other clinical evidence suggests that activated charcoal does not affect the absorption of N-acetyl cysteine.

Likelihood Possible Evidence D
Anticoagulant/Antiplatelet Drugs

Theoretically, N-acetyl cysteine might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.
Clinical research suggests that intravenous N-acetyl cysteine decreases prothrombin time, prolongs coagulation time, decreases platelet aggregation, and increases blood loss in surgical patients. Furthermore, in vitro research suggests that N-acetyl cysteine increases the anticoagulant activity of nitroglycerin.

Likelihood Possible Evidence D
Antihypertensive Drugs

Theoretically, N-acetyl cysteine might increase the risk of hypotension when taken with antihypertensive drugs.
Animal research suggests that N-acetyl cysteine potentiates the hypotensive effects of the angiotensin-converting enzyme inhibitors (ACEIs) captopril and enalaprilat. Theoretically, combining N-acetyl cysteine with other antihypertensive drugs might increase the risk of hypotension.

Likelihood Possible Evidence D
Chloroquine (Aralen)

Theoretically, N-acetyl cysteine might interfere with the antimalarial effects of chloroquine.
Animal research suggests that N-acetyl cysteine might reduce the antimalarial effects of chloroquine by increasing cellular levels of glutathione.

Likelihood Possible Evidence D
N-Acetyl-L-Cysteine full monograph & interactions

Alpha Lipoic Acid5 drug types · 263 drugs

Alkylating Agents

Theoretically, the antioxidant effects of alpha-lipoic acid might alter the effectiveness of alkylating agents.
The use of antioxidants like alpha-lipoic acid during chemotherapy is controversial. There are concerns that antioxidants could reduce the activity of chemotherapy drugs that generate free radicals. However, some researchers theorize that antioxidants might make chemotherapy more effective by reducing oxidative stress that might interfere with apoptosis (cell death) of cancer cells. More evidence is needed to determine what effect, if any, antioxidants such as alpha-lipoic acid have on chemotherapy. Advise patients to consult their oncologist before using alpha-lipoic acid.

Likelihood Possible Evidence D
Anticoagulant/Antiplatelet Drugs

Theoretically, alpha-lipoic acid may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
In vitro, alpha-lipoic acid inhibits platelet aggregation.

Likelihood Possible Evidence D
Antitumor Antibiotics

Theoretically, the antioxidant effects of alpha-lipoic acid might alter the effectiveness of antitumor antibiotics.
The use of antioxidants like alpha-lipoic acid during chemotherapy is controversial. There are concerns that antioxidants could reduce the activity of antitumor antibiotic drugs, which work by generating free radicals. However, some researchers theorize that antioxidants might make chemotherapy more effective by reducing oxidative stress that might interfere with apoptosis (cell death) of cancer cells. More evidence is needed to determine what effect, if any, antioxidants such as alpha-lipoic acid have on chemotherapy involving antitumor antibiotics. Advise patients to consult their oncologist before using alpha-lipoic acid.

Likelihood Possible Evidence D
Thyroid Hormone

Theoretically, alpha-lipoic acid might decrease the effects of thyroid hormone drugs.
Animal research suggests that co-administration of thyroxine with alpha-lipoic acid reduces conversion into the active T3 form.

Likelihood Possible Evidence D
Antidiabetes Drugs

Theoretically, taking alpha-lipoic acid with antidiabetes drugs might increase the risk of hypoglycemia.
Although some small clinical studies have suggested that alpha-lipoic acid can lower blood glucose levels, larger clinical studies in patients with diabetes have shown no clinically meaningful effect. Additionally, co-administration of single doses of alpha-lipoic acid and glyburide or acarbose did not cause detectable drug interactions in healthy volunteers.

Likelihood Unlikely Evidence B
Alpha Lipoic Acid 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

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

Copper2 drug types · 31 drugs

Penicillamine (Cuprimine, Depen)

Theoretically, taking copper with penicillamine might decrease the absorption of penicillamine; separate dosing by at least 2 hours.
Copper chelates penicillamine, which decreases its absorption and may reduce its clinical effects.

Likelihood Probable Evidence D
Contraceptive Drugs

Theoretically, taking copper with contraceptive drugs might increase the levels and toxic effects of copper.
A meta-analysis of clinical studies suggests that chronic use of oral contraceptives increases serum copper levels by a mean of 57 mcg/dL. In most people, this resulted in levels above the normal reference range for copper.

Likelihood Possible Evidence D
Copper full monograph & interactions
The maker

Brand information

Manufacturer and brand details for ViraGuard, from the product label.

Equip

See all Equip products
Name
Equip LLC
City
Austin
State
TX
ZipCode
78702
Web Address
equipfoods.com
Pharmacist Counseling Corner

ViraGuard by Equip: Common Questions

Does ViraGuard by Equip interact with any medications?
Yes. Based on its ingredients, ViraGuard has a known interaction with 1,488 medications, including 10 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
ViraGuard 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.
Can I take ViraGuard if I'm pregnant?
Several ingredients carry cautions or are not recommended in pregnancy. Alpha-lipoic acid, vitamin A (at high doses), vitamin C (at high doses), and licorice should be avoided or used only under medical guidance. Talk with your doctor before taking this product while pregnant—they can advise you based on your specific situation.
Can I take ViraGuard if I'm breastfeeding?
Alpha-lipoic acid, vitamin A, vitamin C, and licorice are not recommended while breastfeeding due to insufficient safety data. Discuss with your doctor or pharmacist before starting this product if you are nursing.
What are the most common side effects?
The most commonly reported side effects are mild and digestive: nausea, vomiting, diarrhea, and heartburn. Headache, metallic taste, and dizziness can also occur. Most adverse effects are dose-related and rare at typical supplement doses.
Does this product actually prevent or treat viral infections?
We don't have effectiveness data in our files showing that ViraGuard as a whole prevents or treats viral infections. Some individual ingredients like vitamin A and vitamin C are studied for other conditions, but not specifically for antiviral protection in this formulation.
Will this interact with my thyroid medication?
Yes—alpha-lipoic acid may theoretically decrease how your thyroid medication works, and vitamin C may increase absorption of levothyroxine. Tell your pharmacist or doctor you're taking ViraGuard before or with any thyroid drug so they can monitor you.
Is this product safe if I have diabetes?
Alpha-lipoic acid and N-acetyl cysteine may theoretically lower blood sugar, which could increase hypoglycemia risk if you take diabetes medications. Discuss with your doctor before starting this product if you have diabetes or take blood-sugar drugs.

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.

ViraGuard label
Go deeper

The Full Monographs Behind ViraGuard’s Ingredients

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

Herb & supplement monograph

Alpha-lipoic Acid

Interacts with 263 drugs

Alpha-lipoic acid (ALA) is an antioxidant made naturally by the body and found in small amounts in foods. It is most studied for diabetic nerve pain, where some evidence suggests it may help...

Read the full Alpha-lipoic Acid monograph → Herb & supplement monograph

Vitamin A

Interacts with 387 drugs

Vitamin A is an essential nutrient important for vision, skin, immune function, and growth. Most people get enough from a balanced diet, and supplements are mainly useful for correcting a tr...

Read the full Vitamin A 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

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

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

N-acetyl Cysteine (nac)

Interacts with 294 drugs

N-acetyl cysteine (NAC) is a supplement form of the amino acid cysteine and a building block for the antioxidant glutathione. It has well-established prescription uses for acetaminophen over...

Read the full N-acetyl Cysteine (nac) monograph → Herb & supplement monograph

Licorice

Interacts with 1,040 drugs

Licorice root is a traditional remedy used for sore throats, coughs, and digestive complaints, but solid human evidence is limited for most uses. Regular licorice contains glycyrrhizin, whic...

Read the full Licorice monograph → Herb & supplement monograph

Selenium

Interacts with 321 drugs

Selenium is an essential trace mineral your body needs in small amounts for thyroid function, antioxidant defense, and immune health. Most people who eat a varied diet get enough, and supple...

Read the full Selenium monograph → Herb & supplement monograph

Copper

Interacts with 31 drugs

Copper is an essential trace mineral your body needs in small amounts for making red blood cells, supporting nerves and bones, and helping enzymes work. Most people get enough copper from fo...

Read the full Copper monograph → Herb & supplement monograph

Grape

Interacts with 910 drugs

Grapes and grape products like grape seed extract contain antioxidant compounds such as resveratrol and proanthocyanidins that may support heart and blood vessel health. While the food is he...

Read the full Grape monograph →
Sources

Sources & How We Checked

ViraGuard'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 503 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.

Alpha-lipoic Acid 48 references
  1. Labriola D, Livingston R. Possible interactions between dietary antioxidants and chemotherapy. Oncology 1999;13:1003-8.
  2. Anon. Alpha-lipoic acid. Altern Med Rev 1998;3:308-10.
  3. Konrad T, Vicini P, Kusterer K, et al. Alpha-lipoic acid treatment decreases serum lactate and pyruvate concentrations and improves glucose effectiveness in lean and obese patients with Type 2 diabetes. Diabetes Care 1999;22:280-7. PubMed
  4. Ziegler D, Hanefeld M, Ruhnau KJ, et al. Treatment of symptomatic diabetic peripheral neuropathy with the antioxidant alpha-lipoic acid: A 3-week, multicentre randomized controlled trial (ALADIN Study). Diabetologia 1995;38:1425-33.
  5. Gleiter CH, Schreeb KH, Freudenthaler S, et al. Lack of interaction between thioctic acid, glibenclamide and acarbose. Br J Clin Pharmacol 1999;48:819-25. PubMed
  6. Jacob S, Henriksen EJ, Tritschler HJ, et al. Improvement of insulin-stimulated glucose-disposal in type 2 diabetes after repeated parenteral administration of thioctic acid. Exp Clin Endocrinol Diabet 1996;104:284-8. PubMed
  7. Jacob S, Henriksen EJ, Schiemann AL, et al. Enhancement of glucose disposal in patients with type 2 diabetes by alpha-lipoic acid. Arzneimittelforschung 1995;45:872-4.
  8. Jacob S, Ruus P, Hermann R, et al. Oral administration of RAC-alpha-lipoic acid modulates insulin sensitivity in patients with type-2 diabetes mellitus: a placebo-controlled, pilot trial. Free Rad Biol Med 1999;27:309-14.
  9. Segermann J, Hotze A, Ulrich H, Rao GS. Effect of alpha-lipoic acid on the peripheral conversion of thyroxine to triiodothyronine and on serum lipid-, protein- and glucose levels. Arzneimittelforschung 1991;41:1294-8.
  10. Beitner H. Randomized, placebo controlled, double-blind study on the clinical efficacy of a cream containing 5% alpha-lipoic acid related to photoaging of facial skin. Br J Dermatol 2003;149:841-9.
  11. Ziegler D, Nowak H, Kempler P, et al. Treatment of symptomatic diabetic polyneuropathy with the antioxidant alpha-lipoic acid: A meta-analysis. Diabet Med 2004;21:114-21.
  12. 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
  13. Conklin KA. Cancer chemotherapy and antioxidants. J Nutr 2004;134:3201S-3204S. PubMed
  14. Vincent HK, Bourguignon CM, Vincent KR, Taylor AG. Effects of alpha-lipoic acid supplementation in peripheral arterial disease: a pilot study. J Alt Complement Med 2007;13:577-84. PubMed
  15. Furukawa N, Miyamura N, Nishida K, et al. Possible relevance of alpha lipoic acid contained in a health supplement in a case of insulin autoimmune syndrome. Diabetes Res Clin Pract 2007;75:366-7. PubMed
  16. Ziegler D., Ametov A., Barinov A., Dyck P. J., Gurieva I., Low P. A., Munzel U., Yakhno N., Raz I., Novosadova M., Maus J., Samigullin, R. Oral treatment with alpha-lipoic acid improves symptomatic diabetic polyneuropathy: the SYDNEY 2 trial. Diabetes Car
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  18. Porasuphatana S., Suddee S., Nartnampong A., Konsil J., Harnwong B., Santaweesuk A. Glycemic and oxidative status of patients with type 2 diabetes mellitus following oral administration of alpha-lipoic acid: a randomized double-blinded placebo-controlled
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See these in context on the Zinc monograph →

N-acetyl Cysteine (nac) 86 references
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See these in context on the N-acetyl Cysteine (nac) monograph →

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See these in context on the Licorice monograph →

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Copper 11 references
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Grape 34 references
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  10. Schaefer, E., Peil, H., Ambrosetti, L., and Petrini, O. Oedema protective properties of the red vine leaf extract AS 195 (Folia vitis viniferae) in the treatment of chronic venous insufficiency. A 6-week observational clinical trial. Arzneimittelforschun PubMed
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  12. de Lange, D. W., Scholman, W. L., Kraaijenhagen, R. J., Akkerman, J. W., and van de Wiel, A. Alcohol and polyphenolic grape extract inhibit platelet adhesion in flowing blood. Eur.J Clin.Invest 2004;34(12):818-824. 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.

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