The over-the-counter stimulant ephedrine, often used to increase endurance and lose weight, is under increasing scrutiny for its possible health risks.

While the precise hazards are still unclear, a variety of reports have linked its use to heart attacks, strokes and seizures, and heatstroke.

Baltimore Orioles pitching prospect Steve Bechler died Monday of heatstroke after a spring training workout in Fort Lauderdale, Fla. His temperature reached 108.

Broward County medical examiner Dr. Joshua Perper said Tuesday that ephedra, the herbal form of ephedrine, probably contributed to Bechler's death. Bechler had been taking Xenadrine, an over-the-counter drug containing ephedra, Perper said.

When the NFL banned ephedrine, it cited concern that the stimulant could interfere with the body's ability to regulate heat. The drug also is banned by the NCAA and the International Olympic Committee, but not by major league baseball.

Ephedra, also known as ma huang, is considered a dietary supplement and is not regulated by the Food and Drug Administration. Because of the health issues, however, the Department of Health and Human Services hired the RAND Corp. last summer to do a comprehensive review.

The concern results, in part, from reports to the FDA of people falling ill or even dying after taking the supplements.

Two years ago, Drs. Christine Haller and Neal Benowitz of the University of California, San Francisco, reviewed 140 of these reports.

They concluded that one-third of the cases definitely or probably resulted from ephedrine, and another third possibly did. These included 10 deaths and 13 cases of permanent impairment.

The most commonly reported ill effects were heart related, including high blood pressure, palpitations and heart attacks. Strokes and seizures, especially in outwardly healthy young adults, were also apparently triggered by ephedrine.

The California doctors estimated that in 1999, about 12 million Americans used the supplements.