Ephedrine is an alkaloid, or chemical compound, found in the plant ephedra and is traditionally used in Chinese medicine and some over-the-counter and prescription medications. More recently, it has been marketed as a diet pill.

Ephedra-containing products stimulate the central nervous system and often include additional stimulants, such as caffeine, to promote weight loss. According to the Food and Drug Administration, ephedra has been found in weight-loss supplements and products to increase energy levels and athletic performance. Some variations of ephedra have even been sold as alternatives to illegal drugs.

The use of ephedrine has been controversial because of side effects such as high blood pressure, rapid heart rate, nerve damage, muscle injury, psychosis and memory loss. More serious results have also been reported, including heart attack, stroke, seizure and death. Because ephedrine and supplements containing it have been linked to unreasonable risk of illness or injury, according to the Mayo Clinic, ephedrine is currently banned in the U.S.

To learn about other potentially dangerous weight-loss drugs, take a look at our list of dangerous diet pills.