Dangers of Herb-Drug Interactions

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Larry Benton was scared. He had read that Asian ginseng might counteract a prescription drug that helps prevent blood clots, and he had been taking precisely that combination for months. But his doctor wouldn’t talk to him about herbs, and his insurance plan didn’t allow for switching doctors or seeing alternative health-care providers. Benton (not his real name) had difficulty finding information beyond the one report he’d seen, yet he said he needed both the herb, which he felt gave him a much-needed energy boost, and the prescription medication, a blood-thinner called warfarin. Afraid to continue taking the combination and afraid to stop, Benton didn’t know which way to turn.

The Good, the Bad and the Unknown

Benton’s dilemma illustrates a potentially problematic side of herbal remedies: When combining herbs with pharmaceuticals, bad interactions may result. But finding information on the subject is difficult, and medical doctors are often hesitant to offer advice. Part of the problem, some say, is that Western medical doctors are just getting acquainted with herbs. And Western science is just beginning to produce the research reports that doctors rely on to make decisions about their patients’ health care.

“Consumers are not well served by our medical climate,” says Amanda McQuade Crawford, a medical herbalist, president of the National College of Phytotherapy in Albuquerque, and founding member of the American Herbalists Guild.

But McQuade Crawford and others say that herb-drug combinations offer many health benefits—provided they are used and/or prescribed carefully.

Among those who believe that herbs and drugs can be effective partners is Mary Hardy, a medical doctor practicing in California and an Herbs for Health editorial adviser. However, whether it’s smart to prescribe an herb-drug combination depends on the needs of the individual patient, she says.

“It’s about balance,” Hardy says, “and about knowing what goal you’re trying to achieve and putting it in context of that goal.”

Why Combine?

Health-care practitioners who prescribe herb-drug combinations say they do so for many reasons, including using herbs to ease side effects from harsh, though potentially life-saving pharmaceuticals. They also use herbs to strengthen the effects of pharmaceuticals (allowing for a lower dose) and help patients withdraw from addictive or potentially harmful drugs. McQuade Crawford, for example, once helped a client who was taking antiviral drugs and a strong diuretic called Lasix to treat hepatitis C, a viral disease that causes the liver to inflame.

“As the doctors kept increasing his Lasix, he became more frightened and they became more pessimistic in their prognosis,” she says. Along with changes in diet, exercise and stress management, McQuade Crawford recommended that her client add potassium-rich dandelion leaf and silymarin, the active compounds in milk thistle, to his regimen, all in addition to the Lasix and antivirals. In three months, he no longer needed the prescription diuretic, she says, and his doctors’ tests showed improvement in his liver enzymes and viral load.