The Food and Drug Administration is investigating reports of liver damage in patients taking alli, the only nonprescription weight-loss drug approved by the agency.
Regulators say they have received more than 30 reports of liver damage in patients taking alli and Xenical, the prescription version of the drug. The reports, between 1999 and October 2008, included 27 hospitalized patients and six who suffered liver failure.
Alli and Xenical are marketed by British drug maker GlaxoSmithKline, although Xenical is manufactured by the Swiss firm Roche.
Roche referred questions to GlaxoSmithKline. A spokeswoman for GlaxoSmithKline said there is no evidence the company's drug causes liver injury, noting that it primarily acts on the intestinal tract. She said alli's safety has been studied in more than 30,000 patients enrolled in 100 clinical studies.