St. John’s wort: This supplement can greatly increase or decrease the potency of many medications and cause serious side effects. Patients who take antidepressants, anti-blood-clotting drugs, certain asthma drugs, immune-suppressing medications or steroids should probably avoid St. John’s wort.
S-adenosylmethionine (SAM-e): This can cause serious side effects when taken with antidepressant medications that affect serotonin.
Garlic, ginseng, ginger and feverfew: Patients who take anti-clotting medications such as aspirin, warfarin (Coumadin) and clopidogrel (Plavix) should avoid these supplements. They may increase the risk of bleeding. Supplements chondroitin and glucosamine also may interfere with warfarin.
Ginkgo: Ginkgo may increase the risk of bleeding in patients taking anti-clotting medications. Ginkgo can counteract the blood pressure-lowering benefits of thiazide diuretic drugs. It also can interfere with anti-seizure medications.
Kava: Kava is a sedative herb and is associated with serious liver problems, even when taken for a short time. Many medications, such as cholesterol-lowering drugs, pose a risk of liver damage. Taking kava may increase the risk of liver problems even more.