Ephedra

Ephedra is a substance extracted from plants that has been used in traditional medicine for centuries. However, its use in dietary supplements as a substance known as "ephedrine", which was popular around the turn of the 21st century, was found to be unsafe and led to a number of deaths, including that of pitcher Steve Bechler in spring training in 2003.

The substance has not been banned by Major League Baseball, as it does not have any performance-enhancing properties. However, it was banned in the minor leagues, and the Players' union cautioned its members against consuming any products containing the substance following Bechler's death.