Long-awaited federal regulations might help improve supplement safety when they begin to take effect in June. The "good manufacturing practices" for dietary supplements are designed to prevent contamination and inclusion of the wrong ingredients and too much or too little of a dietary ingredient. But whether they can stop the spiking of supplements with prescription drugs is uncertain, especially if enforcement is lax. "We can't prevent people from doing illegal acts," says Vasilios Frankos, Ph.D., director of the FDA's division of dietary supplements.

Under the provisions of a separate law that went into effect in December, makers and distributors of supplements and over-the-counter drugs must report all serious adverse events to the FDA within 15 business days. So it's now more important for consumers and health caregivers to report suspect supplements.

Tougher requirements have not closed the most significant gap created by the 1994 Dietary Supplement Health and Education Act. Supplements still don't have to undergo FDA review for safety and effectiveness before they're marketed. The burden remains on the agency to prove that a supplement creates "a significant or unreasonable risk" before it can demand its removal.