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When you take prescription or over-the-counter (OTC) medications, do you also take a vitamin, mineral, or other dietary supplement? Have you considered whether there is any danger in mixing medications and dietary supplements?

There could be. Certain dietary supplements can change absorption, metabolism, or excretion of a medication. If that happens, it can affect the potency of your medication, which means you may get either too much or too little of the medication you need.

Dangers of Mixing Medications and Dietary Supplements

Dietary supplements are widely used and include vitamins, minerals, and other less familiar substances—such as amino acids, botanicals, and botanical-derived ingredients. Tens of millions of people in the U.S. take some kind of dietary supplement along with a prescription medication.

Combining dietary supplements and medications could have dangerous and even life-threatening effects. For example, drugs for HIV/AIDS, heart disease, depression, treatments for organ transplants, and birth control pills are less effective when taken with St. John’s wort, an herbal supplement. Depending on the medication involved, the results can be serious.

In addition, warfarin (a prescription blood thinner), ginkgo biloba (an herbal supplement), aspirin, and vitamin E (a supplement) can each thin the blood. Taking any of these products together may increase the potential for internal bleeding or stroke.

Don’t Assume “Natural” Means Safe

Some consumers may believe that a so-called “natural” product, such as an herbal supplement or fish oil, can’t hurt them. Natural does not always mean safe.

For example, many weight loss products claim to be “all-natural” or “herbal,” but their ingredients may interact with medications or may be dangerous for people with certain medical conditions.

Precautions for Children and for Those Who Are Pregnant or Breastfeeding

Children, in particular, could be harmed by taking both supplements and medicines. Children’s metabolisms are unique, and at different ages they metabolize substances at different rates. For kids, ingesting dietary supplements together with other medications make adverse events a real possibility. And if you’re pregnant or breastfeeding, you’ll want to discuss any dietary supplements with their Health care professional.

Considerations Before Surgery

If you’re planning a surgery, be aware that some dietary supplements can interact in a harmful way with medications you need to take before, after, or during that surgery. Your Health care professional may ask you to stop taking dietary supplements two or three weeks before the procedure to avoid potentially dangerous changes in heart rate, blood pressure, or bleeding risk.

What Is the FDA’s Role in Dietary Supplements?

Although the FDA has oversight of the dietary supplement industry, the supplement manufacturers and distributors are responsible for making sure their products are safe before they’re marketed. Manufacturers are required to produce dietary supplements that meet minimum quality standards, do not contain contaminants or impurities, and are accurately labeled.

The FDA does not review supplements for effectiveness (as it does for OTC and prescription medications) before they enter the market. If the dietary supplement contains certain new dietary ingredients, the manufacturer must submit data on that ingredient’s safety—but not its effectiveness—for the FDA’s review before the manufacturer markets a dietary supplement containing the ingredient.

The FDA can take enforcement actions against manufacturers if their products are found to be adulterated (for example, if an ingredient is unsafe) and/or misbranded (for example, if their labeling is false or misleading). To the extent a product marketed as a dietary supplement bears claims that the product is intended to diagnose, mitigate, treat, cure, or prevent a disease, the FDA may also consider whether it is appropriate to take action against products that are unlawfully marketed as drugs.

Talk With Your Health Care Professional Before Using Supplements

Before you take any dietary supplement or medication—over-the-counter or prescription—it is important to discuss it with your Health care professional.

• Every time you visit a health care professional’s office, bring a list of all the dietary supplements and medications you are currently taking. Include the dosages and how many times a day you take them. Some people find it easiest to throw all their dietary supplements and medications in a bag to bring to the medical visit.
• If you’re thinking of adding a dietary supplement to your daily routine, call your health care professional first, and let them know what other supplements and medications you’re taking.
• Also, tell your health care professional if your health status has changed, particularly if you are pregnant, breastfeeding, or have had any recent illnesses or surgery.

Additional Resources:

Dietary Supplements, FDA 
Information for Consumers on Using Dietary Supplements, FDA