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Turmeric, ginseng, a probiotic, even vitamin C — all of these, when taken in packaged form, are supplements. Some have lined store shelves for decades. Others are ancient cures processed and packaged for 21st-century consumers.
Whatever their history, supplements are everywhere these days, and consumers are eating them up, spending billions each year on capsules, powders and gummies. More than half of adults age 20 and older have taken one in the last 30 days, data from the National Health and Nutrition Examination Survey found — and that percentage increases with age. About 80 percent of women over age 60 take dietary supplements, the same report shows.

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But what many adults don’t realize is that taking some of these supplements alongside prescription drugs and other medicines can have dangerous and even life-threatening effects. A number of supplements can enhance, diminish or negate a prescription drug in ways that can be consequential and unpredictable, says Laura Shane-McWhorter, a clinical professor of pharmacology at the University of Utah.
Still, federal research shows about 34 percent of survey participants — representing roughly 72 million people in the United States — take some kind of dietary supplement along with a prescription medication.
Wondering which supplement-prescription pairings can be risky? Here are six popular supplements and their known effects on some common medications.
1. St. John’s wort
Derived from a flowering shrub native to Europe, St. John’s wort is often taken to treat mild to moderate depression, or to reduce menopausal symptoms such as hot flashes. But it has numerous drug interactions and can reduce the potency of birth control pills and hormone replacement therapy, Shane-McWhorter says. It can also interfere with omeprazole (Prilosec), alprazolam (Xanax), certain statins and some antihistamines, Mayo Clinic reports.
What’s more, St. John’s wort can render Pfizer’s new COVID-19 antiviral treatment, Paxlovid, powerless. “If a person is being treated with Paxlovid and is taking St. John’s wort, that means essentially that the Paxlovid may not work,” Shane-McWhorter says.