Taking medications? Learn the risk of drug interactions with dietary supplements (PART 2 of 3)

The effects of prescription medications can be delayed, made stronger, or made weaker when taken with some dietary supplements.

There are many things people can do to take both prescription and over-the-counter (OTC) medications in a safe manner. One of these is to learn more about drug interactions. There are three main types: drug interactions with foods/beverages, drug interactions with dietary supplements, and drug interactions with other drugs. This article deals with adverse interactions between prescription drugs and dietary supplements.

Dietary supplements include vitamins, minerals, amino acids, herbs or botanicals, as well as other things people use to supplement the foods they eat. We think of supplements as natural and harmless. This is not necessarily so. The effects of prescription medications can be delayed, made stronger, or made weaker when taken with some supplements. Here are some examples of drug interactions with dietary supplements:

St. John’s Wort: This herb can reduce the concentration of medications in the blood. Some of these include cholesterol-lowering drugs (like lovastatin), heart drugs (like Lanoxin/digoxin) and the erectile dysfunction drug Viagra.

Vitamin E:  This supplement shouldn’t be taken with drug-thinning medications, like Coumadin, because it can cause an increased risk of bleeding.

Ginseng: This herb can interfere with the effects of blood-thinning drugs too. It can also increase the bleeding effects of aspirin, heparin, and NSAIDS (non-steroidal anti-inflammatory drugs) such as ibuprofen and naproxen. Combining ginseng with some MAO inhibitors can cause nervousness, sleeplessness, and headache.

Ginkgo Biloba: Taken in high doses, ginkgo can decrease the effectiveness of seizure preventing drugs such as Tegretol and Depakote.

Here are some tips to avoid problems:

  • Ask a doctor or pharmacist what foods and beverages to avoid when taking a medication, a supplement, or an over-the-counter drug.
  • Use one pharmacy or drugstore for all medication needs.
  • Be honest with health care professionals about prescription medications, over-the-counter drugs, and supplements you are currently taking, as well as food preferences.
  • Keep a record of prescription drugs, over-the-counter drugs, dietary supplements and including herbs that are taken. Keep this list handy, especially when doing to medical appointments. A medicine record can be downloaded free at http://www.fda.gov/drugs/resourcesforyou/ucm079489.htm
  • Read drug labels and pharmacy information carefully.
  • Keep medications in their original containers.
  • Review other articles dealing with drug interactions with food and beverages and drug interactions with other drugs.

For more information on using medications safely, please visit U.S. Food & Drug Administration or the Food & Information Center at the USDA Natural Agriculture Library.

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