Weight-loss drugs: Alli and Xenical (Orlistat)

Slim benefits and embarrassing side effects

A review of several thousand adverse event reports from the Food and Drug Administration associated with orlistat—the active ingredient in the over-the-counter (OTC) weight-loss drug Alli and the prescription drug Xenical--has further strengthened our earlier advice: Skip this drug.

The reports, obtained through a Freedom of Information Act request we filed with the FDA earlier this year, show a pattern of adverse events submitted to the agency since Jan. 1, 2007, including rectal bleeding and kidney, liver and thyroid problems. Those reports don't prove that orlistat is to blame; but only that those conditions are associated in the reports with the use of Alli and Xenical. To date, a clear link between the use of the drug and a majority of those side effects has not been firmly established. The FDA is already investigating liver toxicity issues associated with both drugs, and with rectal bleeding with Xenical.

Of the several thousand reports submitted to the FDA, Charles Bennett, director of the Research on Adverse Drug Events and Reports (RADAR) group, which also reviewed the reports said "this safety concern is heightened when one considers that only an estimated 1 percent to 10 percent of all adverse events that occur are ever reported to the FDA."