With bathing-suit season just around the corner, those diet-pill ads online or in the back of many women's magazines can be pretty tempting.  A recent Google of the words "quick weight loss" turned up more than 23 million hits—many of them links to allegedly safe and natural products that promised users could drop 20 pounds or more in a month with no health risks. Some of these products are relatively inexpensive, but others are quite pricey—more than $100 for a month's supply. Don't be fooled. Although many are simply ineffective and will hurt only your wallet, the FDA has recently cracked down on dozens that are downright dangerous.

In a March 20 warning to consumers, the agency said that it had found 72 over-the-counter products that could put consumers' health at serious risk. They included names like Fatloss Slimming, Powerful Slim and 21 Double Slim. An FDA analysis of the ingredients in all 72 of these products showed that they contained undeclared active pharmaceutical ingredients, including the controlled substance sibutramine, an appetite suppressant legally sold as the prescription drug Meridia; rimonabant, a drug not approved in the United States; phenytoin, an antiseizure medication; phenolphthalein, a suspected cancer-causing agent; and the diuretic bumetanide. No prescription drug—even a diet aid like an appetite suppressant—should be taken without medical supervision. And because some of the products contained doses higher than the levels approved for prescription drugs, the risks are higher as well. Potential side effects are scary: seizures, heart attacks and strokes. So much for safe and natural.

The FDA's crackdown on weight-loss pills is continuing, says Michael Levy, director of the agency's division of new drugs and labeling compliance. "We have ramped up our investigation of these types of products as a result of initial positive samples," he says. "I think a large percentage of these products are tainted."

If you think some of these products have names that reflect a certain unfamiliarity with the English language, you're right. Most appear to be coming from China, Levy says, although the only source listed on the box or bottle may be that of the American distributor. But in some cases, the country of origin is obvious. Take a look at the products listed on the site fastdietusa.com many have labels with Chinese characters.

Chinese manufacturers aren't the only culprits. Brazilian diet pills, for example, were the target of an earlier FDA warning because two products, Emagrece Sim and Herbathin, were found to contain fenproporex, a stimulant not approved in the United States. Since fenproporex is converted into an amphetamine in the body, people who take it can test positive for amphetamine use without realizing where the drug comes from. The FDA found that the Brazilian diet pills also contained active ingredients also found in Librium, used to alleviate anxiety, and Prozac, an antidepressant. Taking the pills could cause a host of side effects, from drowsiness to suicidal thinking, and could also interfere with prescription medications.
Still, almost three years later, the Brazilian pills remain popular. In a recent article in the Journal of General Internal Medicine, Dr. Pieter Cohen of the Cambridge Health Alliance in Massachusetts reviewed two cases of patients taking illegal pills from Brazil containing fenproporex. In the first, a 26-year-woman complained of chest pains, headaches and insomnia. Her urine tested positive for amphetamines; the symptoms went away after she stopped taking the pills. In the second case, a 38-year-old man tested positive for amphetamines at work and was suspended from his job. He also experienced heart problems—which disappeared when he quit the pills.

In 2004, the FDA banned the sale of supplements containing ephedra, an ingredient in many herbal weight-loss products, which is linked to heart attacks and strokes. Since then, manufacturers have used concentrated extracts of bitter orange peel instead. But bitter orange may not be safe either, according to the National Center for Complementary and Alternative Medicine (NCCAM).

Even products that aren't necessarily harmful may simply be a waste of money. Hoodia, a cactuslike plant from Africa, is marketed as an appetite suppressant despite the fact that there are no studies of its safety or effectiveness. It's also unclear how much real hoodia is in these products since harvesting is limited by conservation laws. Levy wouldn't comment on whether or not the FDA is investigating hoodia products.

As dangerous as these products are, the FDA's ability to regulate them is limited by the 1994 law on dietary supplements. The agency can't require safety and efficacy tests before these products get to consumers as it does for pharmaceuticals. Instead, the agency can only check out dietary supplements and diet pills that are already for sale. If tests show the pills contain prescription drugs, the manufacturer must recall them. If a company doesn't comply, the FDA can then take stronger action. In its recent warning, the agency indicated that some of the diet-pill manufacturers cited may soon be the target of seizures, injunctions and criminal charges.

In the meantime, this limited regulatory power means consumers have to be on guard for fraud when buying products from this huge and lucrative industry. According to the market-research firm Nutrition Business Journal, consumers spent $1.7 billion on weight-loss pills in 2007.  And a 2007 survey from the Centers for Disease Control (CDC) found that women were more than twice as likely as men to buy them. Because of the potential risks of side effects and drug interactions, Levy says consumers should always tell their doctors about any dietary supplements they are taking. That helps patients stay healthier, avoid trouble and also aids the FDA's efforts to get dangerous drugs off the market. "We think adverse events with this type of product are vastly underreported," Levy says, because consumers don't tell their doctors what products they're using.

The FDA has more detailed information about the risks of weight-loss products on its Web site. If you want to report problems yourself, contact the FDA at 800-FDA-1088 or online at their Web site.

© 2009