Quoted from http://latimesblogs.latimes.com/booster_shots/2010/05/fda-rare-risk-liver-damage-xenical-alli.html
The FDA cites rare risk of liver damage with weight-loss drugs Xenical and AlliMay 26, 2010 | 11:02 am
The Food and Drug Administration said Wednesday that it is ordering a revision of the labels of the weight-loss drugs Xenical and Alli to warn of the risk of very rare cases of severe liver damage associated with their use. The active ingredient in both drugs is orlistat, which blocks the absorption of fats in the intestines. Xenical is a prescription form of the drug. Alli is an-over-the-counter version which contains lower doses.
The agency said it had identified 13 cases of severe liver damage associated with the drugs, one in the United States and 12 abroad. Two of the patients died from liver failure and three others required liver transplants. The FDA said it could not positively say that the drug caused the damage because there is insufficient data in most of the cases. Some of the patients, for example, might have been taking other drugs or had other medical conditions that could have caused the injury. Worldwide, more than 40 million people have taken either Xenical or Alli, so the cases are very rare.
Patients taking the drugs should contact their physicians if they develop itching, yellow eyes or skin, dark urine, loss of appetite, or light-colored stools, all of which are signs of liver damage.