Scottsdale, Arizona - Herbal supplements are natural, so they must be safe, right? Not necessarily. Herbal supplements can have strong effects in the body, and some can interact with prescription medications used to treat heart and circulatory problems, such as high blood pressure and heart failure. Some of these interactions can even be dangerous.

Herbal supplements and prescription medications

Up to one-half of adults who take prescription medications also take dietary supplements, including herbal supplements. That number increases with age.

Yet many herbal supplements may interact with medications for cardiovascular disease — which are widely prescribed for older adults. Indeed, 8 of the 10 most widely used supplements have the potential to interact with the blood-thinning medication warfarin (Coumadin, Jantoven, others). Here are just a few of the herbal supplements that can affect warfarin:

• Danshen
• Dong quai
• Evening primrose oil
• Garlic
• Ginkgo
• Ginseng
• St. John's wort

That's why it's so important to talk with your doctor before taking herbal supplements if you take prescription medications. Your doctor and pharmacist can help you avoid risky interactions.

Herbal supplements and drug interactions

This table shows popular herbal supplements and interactions with common heart medications. It's not a complete list, however, so be sure to discuss with your doctor the medications and supplements you take.

Playing it safe with herbal supplements

If your doctor tells you it's OK to use an herbal supplement combined with a medication, make sure you follow dosing instructions carefully. Watch for any unusual signs or symptoms that you could be having a drug interaction, such as rapid heartbeat, low blood sugar or changes in blood pressure.