For Consumers

Mixing Medications and Dietary Supplements Can Endanger Your Health

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

There could be, says Robert Mozersky, a medical officer at the Food and Drug Administration (FDA). “Some dietary supplements may increase the effect of your medication, and other dietary supplements may decrease it,” he says.

Certain dietary supplements can change absorption, metabolism, or excretion of a medication and therefore affect its potency. “You may be getting either too much or too little of a medication you need,” Mozersky warns.

Consequently, 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.

Dietary supplements are widely used and include vitamins, minerals, and other less familiar substances—such as herbals, botanicals, amino acids, and enzymes. The 2005-2008 National Health and Nutrition Examination Study (NHANES) of the Centers for Disease Control and Prevention (CDC) found that 34% of participants—representing some 72 million people in the United States—were taking some kind of dietary supplement along with a prescription medication. While many people take supplements to ensure an adequate intake of essential nutrients, dietary supplements should not be used as a substitute for eating the variety of foods that makes up a healthy diet.

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

Children, in particular, could be harmed by taking both supplements and medicines. “Parents should know that children’s metabolisms are so unique, that at different ages they metabolize substances at different rates. For kids, ingesting dietary supplements together with other medications make adverse events a real possibility,” Mozersky says.

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.

And if you’re pregnant or breastfeeding, you’ll want to discuss any dietary supplements with your health care professional.

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What is FDA’s Role?

Although FDA has oversight of the dietary supplement industry, it is the supplement manufacturers and distributors that 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.

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

FDA takes enforcement actions against manufacturers if their products are found to be unsafe, adulterated and/or misbranded (for example, if their labeling is false or misleading) or if products marketed as dietary supplements are making claims to diagnose, mitigate, treat, cure, or prevent a disease.

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Tips to Keep in Mind

Thinking about taking dietary supplements?

“The bottom line is, before you take any dietary supplement or medication—over-the-counter or prescription—discuss it with your health care professional,” Mozersky says. Remember these tips:

  • 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 him or her 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.

This article appears on FDA’s Consumer Updates page, which features the latest on all FDA-regulated products.

October 27, 2014

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