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Know the Science: How Medications and Supplements Can Interact

Some Supplements May Decrease the Effects of Drugs

Sometimes, taking a drug and a supplement together may decrease the drug’s effects. This means that you aren’t getting the full benefit from the drug that your health care provider wants you to have.

Drug + Supplement = The drug is less effective than it should be

One popular herbal supplement is especially well known for decreasing the effects of drugs. It does this by speeding up the processes in your body that change drugs into inactive substances. This herb may decrease the effectiveness of more than 70 percent of all drugs.

Which of these herbs is the one that decreases the effects of many drugs?

 Black cohosh


 Saw palmetto

 St. John’s wort

That’s not correct. Try again.

You’re right. St. John’s wort can decrease the effects of many drugs.