Over-the-counter weight-loss pills are no quick fix to melt away extra pounds, according to a cautionary report in the November issue of Mayo Clinic Women's HealthSource.

Many local drugstores sell diet pills, and even more choices are available on the Internet. But most diet pills haven't been proved safe or effective, and some are downright dangerous, the report warns.

The report looks at popular weight-loss diets, eating plans and strategies, including diet pills.

Pills containing ephedra are touted to decrease appetite. But they can cause dangerous side effects, including heart attacks, seizures, strokes and sudden death. Ephedra, although banned by the U.S. Food and Drug Administration, can be purchased online. Herbal supplements that contain the plant-derived chemical ephedrine also are available online and can cause similar health problems.

Other weight-loss pills can contain a cocktail of ingredients, including herbs, botanicals, vitamins, minerals, caffeine or laxatives. It's too often unknown how these ingredients, individually or in combination, could affect individuals. The risk of adverse reactions increases when diet pills are taken with other medications, the report says.

The FDA has approved the weight-loss drug Alli, a reduced-strength version of the prescription drug orlistat. Alli is taken with meals and promotes weight loss by decreasing absorption of fat by the intestines. It's intended for use as part of a reduced-calorie, low-fat diet. When individuals don't reduce fat in the diet, diarrhea and gas with oily spotting can be significant side effects.

While diet pill claims may be tempting, weight loss only happens when more calories are burned than consumed, the report concludes.