Herbal Remedies' Potential Dangers

We've all heard about herbal supplements that have worked for someone we know. People swear by them: echinacea for a cold, ginkgo biloba for memory or the peppermint in the salve your aunt believes can ease chest congestion. Over the past decade, use of herbal supplements has jumped 83%, going from $12.2 billion in U.S. sales in 1996 to a whopping $22.3 billion last year. While many of those users may be skeptical, they figure, Hey, these things are natural; what harm could they do?

As it turns out, in some cases they can do a lot of harm, and a surprising number of people are putting themselves at risk by using herbal supplements without being informed about their actual benefits and potential dangers. A new study conducted at the University of Iowa and published in the June issue of Mayo Clinic Proceedings reveals just how widespread the problem has become.

Researchers found that the most common mistake users of herbal remedies make is believing that the substances they take actually work. An earlier National Institutes of Health study showed that about 19% of Americans take herbal supplements and more than half the time they're using the substances to treat a specific health condition instead of just for general well-being. That's fine, provided the supplements treat those conditions, but in more than two-thirds of cases, the preparations have never been clinically proved to be effective for those uses. And as any scientist will tell you, clinical proof— a randomized, controlled trial— is the gold standard for establishing a drug's usefulness and safety. So a lot of dollars— not to mention medical faith— are being spent on potentially useless treatments.

Aside from making you think you're doing something to alleviate your health problem (and not really treating the ailment at all), herbal supplements present other possible pitfalls. "If a supplement is not effective and not harmful, most physicians probably won't have a problem with it," says Aditya Bardia, an internist at the Mayo Clinic and lead author of the study. "It's when it's not effective and also harmful that it's going to be a cause of concern."

Certain supplements can have adverse effects ranging from nausea and vomiting to life-threatening conditions like liver or kidney dysfunction. For example, in 2002 the U.S. Food and Drug Administration (FDA) released a warning about potential liver damage from kava root, then one of the 10 most popular herbal supplements sold in the U.S. And in 2004 the FDA banned ephedra, a Chinese weight-loss herb, after it was linked to more than 100 deaths. Equally troubling, some Ayurvedic supplements, medications based on Indian and South Asian practices, may be adulterated and thus could be contaminated with dangerous heavy metals, including lead and mercury.

Perhaps the greatest potential risk, however, lies in possible interaction with pharmaceutical drugs you are already taking. Saint-John's-wort, which has been shown to help in treating mild to moderate depression, is also known to reduce the effectiveness of some HIV medications and heart drugs such as digoxin and warfarin— life-and-death meds that it doesn't pay to fool with.

To avoid such complications, ask your doctor before you decide to try an herbal supplement, and be sure to disclose any supplements you're taking even if you're not asked. That can be particularly important when you're being prescribed a new medication. The message here is not to avoid all herbal supplements. Increasingly, Western medicine is improving because of discoveries about these alternative treatments. However, it's important to remember that they are essentially drugs, and the best way to use them is to separate fact from fiction first.

Sanjay Gupta's Fit Nation series airs on House Call on CNN, Saturdays and Sundays, at 8:30 a.m. E.T.

—With reporting by Shahreen Abedin