By GlobalMHSummit.com Research Team
If you take a prescription medicine and are thinking about adding a supplement, or you already take several products at once, a short, prepared conversation with your pharmacist or prescriber is a practical step. This guide gives you a question list and explains what to bring. It does not recommend any product, and it cannot tell you whether a specific combination is safe for you.
The short answer
Bring a written list of everything you take, and ask what each item could do to your other medicines. The National Center for Complementary and Integrative Health (NCCIH) says some supplements can decrease the effects of medicines, while others can increase their effects, including unwanted side effects. NCCIH also notes that for many medicines and supplements there is little information on possible interactions, so “no known problem” is not the same as “no problem.”
What to bring
NCCIH advises bringing a written list of all the prescription and over-the-counter medications you take, including supplements, how often you take them, and the doses. You can also bring the bottles, which helps the person answering your questions see the actual ingredients.
If you are reading an ingredient list on a web page, such as our fat burner supplements guide, treat the page as a starting point only. The label on the bottle in your hand is what a pharmacist can check.
Questions to ask your pharmacist
About the combination
- Here is my full list. Does anything on it interact with anything else?
- Could this supplement make any of my medicines work less well, or work more strongly?
- Are any of my medicines the kind where small changes in the amount in my body matter a lot? (NCCIH calls these medicines with a narrow therapeutic index and names digoxin, cyclosporine, and warfarin as examples.)
- I take a medicine that affects mood or sleep. Could any ingredient on this label raise the risk of side effects when combined with it?
About the product itself
- Can you read this label with me? Is there an ingredient you can't identify or that concerns you?
- Does the way I take it matter, such as the time of day, with food, or spaced apart from my other medicines?
- Does anything here matter for my other health conditions, or for an upcoming surgery or procedure? (NCCIH says certain supplements may increase the risk of bleeding or affect your response to anesthesia, and advises telling your providers about all supplements well before an operation.)
About next steps
- What symptoms should make me stop and call you or my prescriber?
- Should my prescriber know about this too?
- Is there something I should raise with my prescriber about the goal I'm trying to reach, such as sleep, energy, or weight?
Why some examples matter
NCCIH gives several examples of why the questions above are worth asking:
- St. John's wort interacts with many types of drugs. In most cases it speeds up how the body breaks a drug down, lowering drug levels, and it can also raise the risk of serious serotonin-related side effects with certain antidepressants.
- Concentrated green tea supplements can reduce blood levels of some drugs, such as the cholesterol medicine atorvastatin and the beta-blocker nadolol.
- Goldenseal may change how the body processes many drugs, including the diabetes medicine metformin.
These are examples from NCCIH's tip sheet, not a complete list, and they do not mean any of these products is right or wrong for you. If you take a prescribed medicine, do not stop or change it on your own because of something you read. Talk to your prescriber first.
A label may not tell the whole story
The FDA warns that some products contain hidden ingredients that are not on the label, often prescription drug ingredients, banned substances, or harmful chemicals. FDA says it does not approve dietary supplements before they are sold, and that its health fraud product database covers only a small fraction of contaminated products, so a product missing from the list is not proven safe. NCCIH similarly notes that hidden prescription drugs or other compounds have been found, particularly in supplements marketed for weight loss, sexual health, and athletic performance or body-building.
FDA's advice includes being wary of products that promise results that seem too good to be true, of products with many rave reviews, and of claims of being made in an “FDA-approved facility,” because FDA does not approve facilities. You can also report a suspicious product to FDA to be tested for hidden ingredients.
Limits of this guide
- Interaction research is incomplete. Absence of a warning is not proof of safety.
- FDA publishes a table of enzyme and transporter examples used in drug interaction studies under its drug development resources. It states that it is not an exhaustive list, and it is not a tool for checking your own supplements.
- NCCIH says people being treated for cancer or HIV should discuss all supplement use with their health care provider, because of concern that supplements may interfere with those treatments.
- This article is general education from the GlobalMHSummit.com Research Team. It has not been reviewed by a clinician and does not replace advice from your pharmacist or prescriber. See our Medical Disclaimer and Editorial Standards.
What to do next
- Write down everything you take, including doses and timing.
- Take the list and the bottles to your pharmacist, or to your prescriber at your next visit.
- Ask the questions above and write down the answers.
- Seek urgent help if you feel seriously unwell after starting something new.
Sources
All pages below were opened and checked on October 6, 2026.
- U.S. Food and Drug Administration, Avoiding Products Contaminated with Hidden Ingredients (page lists content as current as of June 10, 2025).
- U.S. Food and Drug Administration, Drug Development and Drug Interactions: Table of Substrates, Inhibitors and Inducers (page lists content as current as of June 5, 2023).
- National Center for Complementary and Integrative Health, 6 Tips: How Herbs Can Interact With Medicines.
- National Center for Complementary and Integrative Health, 5 Tips: What Consumers Need To Know About Dietary Supplements.
- National Center for Complementary and Integrative Health, Know the Science: Talk With Your Health Care Providers.
- National Center for Complementary and Integrative Health, Using Dietary Supplements Wisely (page lists last update as January 2019).