Nature Isn't Always Safe. Remember Rattlesnakes?

Here's the thing about herbal supplements: Everyone wants them to work as well as synthetic medication, but few are inclined to recognize their thoroughly pharmacological qualities. Of course, as this week's issue of the Lancet points out, sometimes those qualities become glaringly clear. According to the British medical journal, St. John's wort, an enormously popular herbal supplement with purported antidepressant qualities, can interact with medicines prescribed for treatment of HIV and heart disease, effectively nullifying the drugs' presence in the patient's bloodstream.

"It's informally recommended that doctors ask patients what herbs or supplements they're taking before they write a prescription," says TIME medical correspondent Dr. Ian Smith. That lax attitude may not be enough to keep patients safe, researchers warn. In January, CVS, one of the nation's largest pharmacy chains, started asking customers to include herbs and nutritional supplements in their list of current medications. Because St. John's wort is so popular, and because it's generally not considered a "real" drug, it may take some time for consumers to get used to mentioning it when they visit the doctor. For their own safety, says Dr. Smith, patients should make full disclosure a habit. "We don't really know what's in herbs like St. John's wort," adds Smith. "We need to establish safety guidelines for all supplements — and that will be a process of trial and error."