Herbal supplements are natural, so they must be safe, right? Not necessarily.
Herbal supplements can have strong effects in the body. 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.
About half of U.S. adults report taking supplements. But research suggests that most don't tell their doctors about this use — even those who also take prescription medications.
Yet many herbal supplements may interact with prescription medications, including some used to prevent or treat heart disease.
That's why it's so important to talk with your doctor before taking herbal supplements if you take prescription medications. Your doctor and your pharmacist can help you avoid risky interactions.
Herbal supplements and drug interactions
Several popular herbal supplements interact with common heart medications. This list covers only some interactions. It's important to talk to your doctor before taking any herbal supplements if you take prescription medications.
Taking coenzyme Q10 can decrease:
- The effectiveness of warfarin (Jantoven)
- Your blood pressure if you also take a calcium channel blocker, such as diltiazem (Cardizem, Tiazac, others)
Danshen can interact strongly with certain heart medications, including:
- Anticoagulants. Taking danshen significantly increases your risk of bleeding if you also take warfarin or another anticoagulant, such as clopidogrel (Plavix) or aspirin.
- Calcium channel blockers. Taking danshen increases your risk of low blood pressure if you also take diltiazem or another calcium channel blocker.
- Digoxin (Lanoxin). Taking danshen increases the effects of digoxin — which is used to treat a variety of heart conditions — and puts you at risk of irregular heartbeat (arrhythmia).
Evening primrose may increase your risk of bleeding if you also take an anticoagulant, such as:
Garlic increases your risk of bleeding if you also take an anticoagulant, such as:
Ginkgo biloba increases your risk of bleeding if you also take:
Taking ginseng with warfarin decreases warfarin's effectiveness.
Hawthorn might interact with:
- Beta blockers, such as atenolol (Tenormin), nadolol (Corgard) or propranolol (Inderal, Innopran, Hemangeol)
- Calcium channel blockers, such as diltiazem, nifedipine (Procardia) and verapamil (Calan SR, Verelan)
- Nitrates, such as nitroglycerin (Nitrostat, Nitro-Dur, others) and isosorbide (Dilatrate-SR, Isordil)
Licorice decreases levels of warfarin and can increase the effects of digoxin.
Saw palmetto increases your risk of bleeding if you also take:
St. John's wort
Taking St. John's wort reduces the effectiveness of:
- Calcium channel blockers
- Statins, such as atorvastatin (Lipitor), lovastatin (Altoprev) and simvastatin (Flolipid, Zocor)
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 signs that you could be having a drug interaction, such as:
- Rapid heartbeat
- Changes in blood pressure