Many people don’t realize it, but you can have a negative drug interaction even with over-the-counter drugs. Ginkgo biloba and garlic can increase bleeding risks if you take anticlotting drugs. And St. John’s wort can reduce the effectiveness of warfarin and certain statins, channel blockers and digoxin (AARP Bulletin June Issue, page 22). Grapefruit and grapefruit juice can increase side effects of many medications, including certain statins, blood pressure and heart-rhythm drugs, according to the U.S. Food and Drug Administration. Alcohol can increase drowsiness and raise the risks of overdoses when used with many drugs for anxiety, seizures or depression, according to the National Institutes of Health. Talk to your doctor about these issues!