Q: Are there any good prescription or over-the-counter diet drugs?
A: It has been nearly impossible to design a diet drug that’s both effective and safe. Just ask the pharmaceutical industry—or the Food and Drug Administration (FDA), which in the past year or so has denied approval for at least three hopeful contenders due to safety concerns.
And a number of previously approved diet pills have been withdrawn from the U.S. market—most recently Meridia (sibutramine), because it can increase the risk of heart attacks and strokes. That leaves few FDA-approved options.
- Over-the-counter. The only OTC drug approved for weight loss is Alli (orlistat), which is a half-strength version of prescription Xenical (see below). By limiting fat absorption in the intestines, Alli can help you lose a few more pounds than you would from diet and exercise alone (about five extra pounds over six months), company research indicates. But when the unabsorbed fat travels lower down in the digestive tract, it can cause frequent and urgent bowel movements, loose stools and flatulence, particularly if you don’t stick to a very low-fat diet. The drug also reduces absorption of vitamins A and D and other fat-soluble nutrients. Moreover, in 2010, the FDA began warning users of orlistat about the rare risk of severe liver injury.
- Prescription. Drugs such as Adipex-P, Ionamin and Tenuate contain phentermine or other central nervous system stimulants and are intended only for short-term use. They suppress appetite, but may also increase blood pressure and heart rate, cause dizziness and insomnia, and have other adverse effects. If used longer, they can be habit-forming.The fat-blocker Xenical (orlistat), approved in 1999, was, until recently, the only prescription drug available for longer-term use. (Editor's note: Since the publication of this article, two new prescription diet medications have been approved.)
The drawbacks of these drugs usually outweigh their potential benefits, and they should be taken only after careful consultation with your doctor. Other prescription medications, including antidepressants and the diabetes drug metformin, are sometimes used (off-label) for weight loss, but they also have side effects.