FDA warns consumers to beware of counterfeit alli

The U.S. Food and Drug Administration is warning consumers to beware that a counterfeit version of the over-the-counter diet drug alli is being sold on the Internet.

GlaxoSmithKline, which makes alli, told the FDA that its lab tests showed the counterfeit version does not contain orlistat -- the active ingredient in alli. Fake alli contains sibutramine, the main ingredient used in the prescription appetite suppressant Meridia.

In its warning the FDA said part of the danger of the fake alli is how the medication would interact with other drugs the user is taking. Sibutramine also should not be used by people with certain medical conditions and is supposed to be administered under the watch of a physician.