Weight Loss Medications

Two prescription drugs have been approved by the Food and Drug Administration (FDA) for long-term use. These drugs work in different ways and cause different side effects.

1. Sibutramine (Meridia). This drug changes your brain chemistry, making you feel full more quickly. Sibutramine can help you lose more weight than you could through diet and exercise alone. Studies have shown that after a year, sibutramine users lost an average of about 10 pounds more than did people who followed a low-calorie diet along with placebo. Side effects can include increased blood pressure and heart rate, headache, dry mouth, constipation and insomnia.

2. Orlistat (Xenical). This drug prevents the absorption of fat in your intestines. Unabsorbed fat is eliminated in the stool. Average weight loss with orlistat is about 6 pounds after one year. Side effects associated with the drug include oily discharge and frequent bowel movements. Because orlistat blocks absorption of some vitamins, your doctor will recommend that you also take a multivitamin.

The FDA has approved a reduced-strength version of orlistat (Alli) to be sold without a prescription. This medication works the same as prescription-strength orlistat. If you're among those who can benefit from weight-loss medication, you'll likely need to take it indefinitely. When drug treatment is stopped, much or all of the excess weight generally returns.

• Even if you qualify for weight-loss drug therapy, the drugs might not work for you. And, if they do work, their effects tend to level off after six months of use.