One in six older adults are at risk of a major drug-drug interaction. That’s when one drug affects the way another one works. Potential adverse effects range from kidney failure to heartbeat irregularities. Here are some dangerous combinations to avoid:

• Amlodipine and simvastatin—risk of nerve damage, muscle injury, kidney failure

• Warfarin and simvastatin—risk of bleeding, muscle damage, kidney failure

• Aspirin and clopidogrel bisulfate—risk of bleeding

• Aspirin and naproxen—risk of bleeding, ulceration, perforation

• Clopidogrel bisulfate and omeprazole—risk of serious blood clots

• Niacin and some statins—risk of nerve damage, muscle injury, kidney failure

• Lisinopril and potassium—risk of hyperkalemia (a buildup of potassium that can cause heartbeat irregularities)