Interactions by Drug Class
A guide to supplement and food interactions by medicine group, with what official sources document, how firm each statement is, and links to a full page for every group.
Content last updated . This page has not been medically reviewed.
Use this page to find the right page, not to clear a combination. "Not on this list" does not mean safe: the sources we read cover only some medicines and some supplements, and a lack of reports is not proof of safety. Ask a pharmacist. For a poisoning or emergency in the US: 911, 988 (mental health crisis) or Poison Help 1-800-222-1222.
How to read the table
Each row names a group of medicines (not brands), what a named official source says, and our label: documented, reported, preliminary, theoretical, or "source caution" when a regulator or health service warns without study detail. The labels are explained in How interactions work. No row tells anyone to start, stop or change a prescribed medicine; that is for the prescriber or pharmacist. No amounts are given.Groups with a full page
| Medicine group | What sources we read document | Label | Full page |
|---|---|---|---|
| Blood thinners (warfarin, aspirin, newer anticoagulants) | NCCIH: St. John's wort weakens warfarin; ginkgo and garlic supplements may raise bleeding risk; glucosamine may increase warfarin's effects. [1][2][3][4] | Documented; documented caution | More about Blood thinners (warfarin, aspirin, newer anticoagulants) → |
| Antidepressants (SSRIs, SNRIs, MAOIs) | NCCIH: St. John's wort with certain antidepressants may raise serotonin-related side effects, which can be serious. [5] SAMe might interact with serotonin-raising drugs. [6] | Documented; theoretical | More about Antidepressants (SSRIs, SNRIs, MAOIs) → |
| Blood pressure and heart medicines | NCCIH: St. John's wort may weaken digoxin and ivabradine; licorice can cause serious heart effects in some people. [5][7] FDA: grapefruit juice can affect nifedipine and amiodarone. [8] | Documented | More about Blood pressure and heart medicines → |
| Diabetes medicines | NCCIH: goldenseal extract plus metformin lowered metformin levels by about 25 percent in healthy adults. [1] Asian ginseng might lower blood sugar. [9] | Preliminary; stated risk | More about Diabetes medicines → |
| Statins and cholesterol medicines | NCCIH: St. John's wort may weaken simvastatin; green tea extract can lower atorvastatin levels. [5][10] FDA: grapefruit can affect some statins. [8] | Documented; preliminary | More about Statins and cholesterol medicines → |
| Thyroid medicines | Not described in the sources used for this index. | Proper evidence not found here | More about Thyroid medicines → |
| Transplant and immune-suppressing medicines | NCCIH: St. John's wort may weaken cyclosporine. [5] FDA: grapefruit can affect cyclosporine. [8] | Documented | More about Transplant and immune-suppressing medicines → |
| Cancer treatment | NCCIH: growing concern that supplements may interfere with cancer treatments; St. John's wort may weaken irinotecan, imatinib and docetaxel. [11][5] | Documented caution | More about Cancer treatment → |
| HIV, antiviral and antibiotic medicines | NCCIH: growing concern about HIV treatments; St. John's wort may weaken indinavir and nevirapine. [11][5] | Documented | More about HIV, antiviral and antibiotic medicines → |
| Birth control and hormone medicines | FDA: birth control pills are less effective with St. John's wort. [12] | Documented | More about Birth control and hormone medicines → |
| Sedatives, sleep medicines and alcohol | NCCIH: preliminary evidence that ashwagandha may increase the effects of some benzodiazepines and other sedatives; kava should not be used with benzodiazepines or alcohol. [4][13] | Preliminary; documented caution | More about Sedatives, sleep medicines and alcohol → |
| Pain medicines (NSAIDs, acetaminophen, opioids) | The NHS lists aspirin and NSAIDs among medicines that may not mix well with warfarin. [14] | Source caution | More about Pain medicines (NSAIDs, acetaminophen, opioids) → |
| Seizure medicines | NCCIH: St. John's wort may weaken phenytoin and carbamazepine. [5] | Documented caution | More about Seizure medicines → |
| Corticosteroids | NCCIH: interactions between licorice and corticosteroids have been reported. [7] | Reported | No separate page yet; see the licorice entry on the heart medicines page above |
| Allergy medicine (fexofenadine) | NCCIH: black cohosh and St. John's wort may interfere with it. [15] FDA: grapefruit juice can lower how much enters the blood. [8] | Stated risk; documented | More about Allergy medicine (fexofenadine) → |
Herbs and foods with their own interaction pages
- St. John's wort interactions: the herb with the longest documented list.
- Grapefruit and medicine interactions: a food, with FDA examples.
- Food and drink interactions with medicines: grapefruit, vitamin K, alcohol and others.
Medicines where a small change matters most
NCCIH's examples of narrow therapeutic range medicines are carbamazepine, cyclosporine, digoxin, phenytoin and warfarin. [16] See Narrow-range medicines and supplements.Checking your own list
Bring a written list or the bottles to every provider visit. [11] The page How to check an interaction safely explains what a pharmacist can do and which official resources exist. A one-page overview is at Interaction risk at a glance.What this page does not cover
Over-the-counter and prescription medicines not listed above, herbal products that contain several ingredients, and traditional medicine products. Interactions with products of uncertain quality are a separate risk; see Quality testing and certifications.Frequently asked questions
Is there a list of supplements that are safe with all medicines?
No. NIH says that interactions can raise, lower or change the effect of a medicine in harmful ways, and to talk with your providers about everything you take. [17]
Which herb has the most documented interactions?
NCCIH says it has been clearly shown that St. John's wort can interact in dangerous, sometimes life-threatening ways with a variety of medicines. [5]
My medicine is not on the table. Is it fine?
Not necessarily. The table covers what we could read, not every medicine. Ask a pharmacist.
Do supplements interact with over-the-counter medicines too?
Yes, they can. NCCIH gives fexofenadine as an example. [15]
Who is most at risk from an interaction?
NCCIH singles out people on narrow-range medicines and people having surgery. [16] See Who should ask first.
References
- National Center for Complementary and Integrative Health (NIH, US). Know the Science: Some Supplements May Decrease the Effects of Medications. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). Ginkgo: Usefulness and Safety. Last updated February 2025. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). Garlic: Usefulness and Safety. Last updated February 2025. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). Know the Science: Some Supplements May Increase the Effects and Side Effects of Medications. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). St. John's Wort: Usefulness and Safety. Last updated May 2025. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). S-Adenosyl-L-Methionine (SAMe): In Depth. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). Licorice Root: Usefulness and Safety. Last updated April 2025. Read 2026-10-23.
- U.S. Food and Drug Administration. Grapefruit Juice and Some Drugs Don't Mix. Consumer update, content current as of 2021-07-01. Read in full 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). Asian Ginseng: Usefulness and Safety. Last updated February 2025. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). Green Tea: Usefulness and Safety. Last updated February 2025. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). Know the Science: Talk With Your Health Care Providers. Read 2026-10-23.
- U.S. Food and Drug Administration. Mixing Medications and Dietary Supplements Can Endanger Your Health. Consumer update, content current as of 2022-06-02. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). Kava: Usefulness and Safety. Last updated April 2025. Read 2026-10-23.
- NHS (England). Warfarin. Next review due 24 February 2029. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). Know the Science: Interactions With Over-the-Counter Medications. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). Know the Science: Some Medication-Supplement Interactions Can Be Serious. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). Know the Science: How Medications and Supplements Can Interact, Introduction. Read 2026-10-23.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.