(Health.com) -- If you take heart medication, you may want to avoid some of the most popular over-the-counter herbal supplements on the market, including ginseng, saw palmetto, and echinacea. These herbal remedies -- and many others -- can cause potentially serious problems in people taking heart medications, a new report warns.
"These products are not by themselves dangerous," says the lead author, Dr. Arshad Jahangir, a cardiologist and professor of medicine at the Mayo Clinic in Scottsdale, Arizona. "But when taken with medications for cardiovascular diseases, a relatively safe compound can become dangerous."
Herbal remedies such as ginseng, ginkgo, garlic, black cohosh, St. John's wort, hawthorn, saw palmetto, and echinacea can dilute, intensify, or exacerbate the side effects of prescription heart drugs such as blood thinners and cholesterol-lowering statins, the report says.
Some supplements may also increase heart rate and blood pressure, causing potential complications in heart patients.
The report, published this week in the February 9 issue of the Journal of the American College of Cardiology, lists more than 25 herbal products that people with cardiovascular diseases should avoid, including 12 of the 20 best-selling herbal supplements in the United States, according to the American Botanical Council.
For instance, St. John's wort, which is often taken to treat depression and anxiety, affects how the body absorbs dozens of prescription medications and may diminish the efficacy of statins and beta-blockers, a class of drugs used to treat high blood pressure and heart-rhythm disorders.
Herbal supplements such as garlic and ginkgo, meanwhile, can interfere with blood thinners (most notably warfarin) and increase the risk of bleeding associated with those drugs.
"Stay away from the four G's: garlic, ginkgo, ginseng, and ginger," says Dr. Elsa-Grace Giardina, a cardiologist at Columbia University, in New York, who has studied herbal remedies and heart drugs but did not participate in the current report. "They all have effects on bleeding."
Even grapefruit juice, which people often drink for weight loss and heart health, can increase the blood concentration of statins, raising the risk of liver damage and muscle pain, the report notes.
Older people should be especially mindful of interactions such as these, since they are much more likely than younger people to have heart problems and may be taking a half-dozen prescription drugs or more, Dr. Jahangir says.
Many heart patients -- and even some doctors -- aren't aware of the dangers of mixing heart drugs and herbal products, he adds. Doctors rarely ask for a detailed list of the alternative remedies that patients take, and patients seldom volunteer that information.
"Patients will typically discuss prescription or over-the-counter medicines, but in their minds these [herbal] compounds are not medicines," Dr. Jahangir says.
Mixing heart medicine and herbal products is made even more risky by the lack of scientific evidence and regulation for herbal products and other dietary supplements, the report suggests. Although the potency of some herbal products can rival that of some prescription medicines, they are not subject to the same checks that prescription drugs are.
Few herbal products have been widely tested for safety and efficacy in randomized, placebo-controlled trials, as the U.S. Food and Drug Administration (FDA) requires of prescriptions drugs. Moreover, the FDA does not approve dietary supplements before they appear on the market, and monitors the safety and purity of herbal products only if consumers report side effects or other problems.
As a result, many popular herbal products haven't been proven to work, and some contain impurities or inconsistent amounts of the active ingredient.
"The public believes there is a check on everything, which is not true at all," says Dr. Jahangir.
For her part, Dr. Giardina recommends that heart patients -- and anyone else, for that matter -- steer clear of herbal products.
"Frankly, I would just avoid them all," she says. "Go into your medicine cabinet and get rid of anything you bought in an herbal store that you take in a pill form. Save your money and go buy a pair of shoes."
Copyright Health Magazine 2011