On Wednesday, the U. S. health officials announced that revised labels should be used by weight-loss drugs following reports of rare but sometimes severe cases of liver damage.

Under the trade name Xenical and over-the-counter as Alli, the drug, orlistat, is available by prescription.

According to a statement from the U. S. Food and Drug Administration, by taking orlistat about 13 cases of severe liver injury have been reported. Out of these 13 cases, 12are from overseas and one of them, from Alli, in the United States.

Dr Eugene Schiff, director of the Center for Liver Diseases at the University of Miami Miller School of Medicine, said that according to FDA estimates, consumers needn't be too worried about the risk despite some 40 million people worldwide are taking the drug.

He added, "The issue here is that they are identifying cases, not many, but some cases of severe liver injury."

FDA spokeswoman Elaine Gansz Bobo said, "We are telling consumers and health-care providers to be vigilant if patients develop symptoms suggestive of liver impairment."

Presently only an association between the rare side effect of the drug is being stated by the FDA.