The Food and Drug Administration said the fat-blocking weight-loss pill orlistat, which has been available by prescription, can be sold in a reduced-strength version over the counter.
The new version will be sold as "alli" by GlaxoSmithKline PLC. Xenical, the prescription version, is made by Roche Holding AG.
GlaxoSmithKline chose the name "alli" because it's supposed to be "allied" with a weight-loss program, including exercise and healthy eating, reports CBS News correspondent Dan Raviv.
The drug is intended for people 18 and older to use along with a reduced-calorie, low-fat diet and exercise.
Dr. Charles Ganley, FDA's director of nonprescription products, stressed that the drug is intended for use along with diet and exercise programs.
"Using this drug alone is unlikely to be beneficial," Ganley said at a telebriefing.
While some dietary supplements make weight-loss claims, Ganley said this is the first nonprescription drug approved by the agency for that purpose.
Ganley said in trials, for every five pounds people lost through diet and exercise, those using orlistat lost an additional two to three pounds.
When taken with meals, orlistat blocks the absorption of about one-quarter of any fat consumed. That fat — about 150 to 200 calories worth — is passed out of the body in stools, which can be loose as a result. About half of patients in trials experienced gastrointestinal side effects.
The agency recommended users take a multivitamin when using this drug.
The new drug would contain half the dose of Xenical prescription capsules. The price has not been set but is expected to run $1 to $2 a day, company officials said. The company estimated 5 million to 6 million Americans a year would buy the drug over the counter.
The Food and Drug Administration said the most common side effect of the product is a change in bowel habits including loose stool and some oily spotting. Eating a low-fat diet will reduce the likelihood of this side effect.
FDA said people who have had organ transplants should not take OTC orlistat because of possible drug interactions. In addition, anyone taking blood-thinning medicines or being treated for diabetes or thyroid disease should consult a physician before using orlistat, the agency said.
GSK Consumer Healthcare, which will market the pill, said it chose the name alli to indicate a partnership with consumers in their weight-loss efforts.
"We know that being overweight has many adverse consequences, including an increase in the risk of heart disease and type 2 diabetes," said Dr. Douglas Throckmorton, deputy director for the FDA's Center for Drug Evaluation and Research.
"OTC orlistat, along with diet and exercise, may aid overweight adults who seek to lose excess weight to improve their health," he said.
But Dr. Sidney M. Wolfe, director of Public Citizen's Health Research Group, called the approval "the height of recklessness." Wolfe said studies have associated the prescription version of the drug with precancerous lesions of the colon. He has also called for withdrawal of the prescription version.