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.
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:
- Dong quai
- Evening primrose oil
- 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.
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.
- Clopidogrel (Plavix)
- Warfarin (Coumadin, Jantoven, others)
|Increases risk of bleeding
|Increases risk of bleeding
||Decreases effectiveness of warfarin
- Beta blockers, such as atenolol (Tenormin), nadolol (Corgard) and propranolol (Inderal LA, Innopran XL)
|Increases blood pressure and heart rate
- Calcium channel blockers, such as diltiazem (Cardizem, Dilacor XR, others), nifedipine (Procardia) and verapamil (Calan, Covera-HS, others)
- Nitrates, such as nitroglycerin (Nitro-Bid, Nitrostat, others) and isosorbide (Dilatrate-SR, Isordil)
|Decreases blood pressure
- Digoxin (Lanoxicaps, Lanoxin)
|Increases effects of digoxin
||Decreases levels of warfarin
|St. John's wort
- Calcium channel blockers
- Statins, such as atorvastatin (Lipitor), lovastatin (Mevacor, Altoprev) and simvastatin (Zocor)
|Reduces effectiveness of drugs
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.
Oct. 10, 2014
- Herbal and nonherbal supplements a danger for warfarin patients. American Heart Association. http://www.theheart.org/article/1079777.do. Accessed Sept. 1, 2014.
- Most patients don't tell their doctors they take supplements: But they can interact with prescription medications. AARP. http://www.aarp.org/health/drugs-supplements/info-11-2010/most_patients_dont_tell_their_doctors_they_take_supplements.html. Accessed Sept. 1, 2014.
- Avoid food-drug interactions. http://www.fda.gov/downloads/drugs/resourcesforyou/consumers/buyingusingmedicinesafely/ensuringsafeuseofmedicine/generaluseofmedicine/ucm229033.pdf. Accessed Sept. 1, 2014.
- Keifer DS, et al. The overlap of dietary supplement and pharmaceutical use in the MIDUS national study. Evidence-Based Complementary and Alternative Medicine. 2014:823853.
- Hsin-Hui Tsai, et al. A review of potential harmful interactions between anticoagulant/antiplatelet agents and Chinese herbal medicines. PLOS ONE. 2013;8:e64255.
- Garlic. Natural Medicines Comprehensive Database. http://www.naturaldatabase.com. Accessed Sept. 1, 2014.
- Hawthorn. Natural Medicines Comprehensive Database. http://www.naturaldatabase.com. Accessed Sept. 1, 2014.
- Tell your health care provider about your use of complementary health practices. National Center for Complementary and Alternative Medicine. http://nccam.nih.gov/timetotalk/forpatients.htm. Accessed Sept. 1, 2014.
- Evening primrose oil. National Center for Complementary and Alternative Medicine. http://nccam.nih.gov/health/eveningprimrose. Accessed Sept. 1, 2014.
- Gingko. Natural Medicines Comprehensive Database. http://www.naturaldatabase.com. Accessed Sept. 1, 2014.
- St. John's wort. Natural Medicines Comprehensive Database. http://www.naturaldatabase.com. Accessed Sept. 1, 2014.
- Ginseng. Natural Medicines Comprehensive Database. http://www.naturaldatabase.com. Accessed Sept. 1, 2014.