Seizures. Chest pain. Heart attacks.

Dr. Michael Mullins has seen them all in people taking ephedra, a common ingredient in popular weight-loss products such as Metabolife. He doesn''t see many, but those he does are enough to convince him that people should avoid the amphetaminelike herbal supplement.

"I would be very careful about taking it," said Mullins, an assistant professor of emergency medicine at Washington University in St. Louis and a toxicology consultant at Barnes-Jewish Hospital. "Of course, I would prefer people weren''t taking it at all."

Dr. Anthony Scalzo is more direct.

"My feeling is you don''t need it," said Scalzo, director of the division of toxicology at St. Louis University. "I know drugs taken off the market as dangerous that have had far fewer reports of complications than ephedra or ephedrine."

The potential deadly side effects of ephedra hit national headlines again two weeks ago when Baltimore Oriole pitching prospect Steve Bechler died of a heatstroke that sent his temperature to 108 degrees.

Trying to lose weight, Bechler was taking Xenadrine RFA-1, which is readily available at nutrition stores. Results of an autopsy suggested that the ephedra, the 81-degree humid heat, liver problems and borderline high blood pressure all played a role.

Bechler''s death came less than two years after the Minnesota Vikings lineman Korey Stringer collapsed and died during a summer training camp workout.

Although ephedra was not linked to his death, a bottle of ephedra-containing Ripped Fuel was found in his locker. As a result, the National Football League not only banned the substance, but also began random testing of players.

But you don''t have to look for high-profile cases to uncover the potential dangers. A November 2000 study in the New England Journal of Medicine reported at least 54 deaths and about 1,000 reports of complications linked to ephedra and ephedrine since the mid-1990s. The Food and Drug Administration later pointed to 80 deaths. Lawyers looking to sue Metabolife and other products abound on the Internet.

The Ephedra Education Council, the public relations arm of the ephedra industry, argues that the substance is safe when taken as directed. For example, Bechler was reported to have taken three Xenadrine tablets each morning; the recommended dosage is two, twice a day.

The council says that, based on its own surveys, between 12 million and 17 million Americans consume more than 3 billion doses of ephedra products each year. Existing data show them to be safe and effective.

Mullins and Scalzo, however, heatedly dispute that conclusion for several reasons.

Ephedra raises blood pressure and increases the heart rate, making it potentially dangerous for people with heart problems or other vascular disease. If blood pressure rises too high, it can cause a stroke.

"I can tell you that I''ve seen someone who had a seizure because they were taking an ephedra-containing weight-loss product with some other medications," Mullins said. "And I can think of another person I''ve seen who had chest pain and on their EKG and lab tests it indicated they were in the process of having a small heart attack."

Scalzo argues that such supplements actually work against your body. In Bechler''s case, for example, the Xenadrine was constricting his blood vessels at a time when he was working out and needing more blood going to his muscles.

"It does what adrenalin does -- break down fat in the body to form energy -- but your body''s already doing that," Scalzo said. "If you just exercise, your own adrenalin is released."

That''s not the only concern. Ephedra is considered a dietary supplement, not a drug, under the Dietary Supplement and Health Education Act of 1994. As such, there is no government agency that guarantees that the dose on the bottle is actually what''s in the pill or liquid. Even one pill may differ in strength from another in the same bottle.

"The Food and Drug Administration has not determined that they''re safe or effective or anything," Mullins said. "The idea that it''s on a store shelf and I can buy it because it''s been found safe just isn''t true."

Yet because it is sold over the counter, consumers may regard warnings less seriously, figuring it won''t do any harm if they take a couple more doses than what is recommended on the bottle.

"It''s thought of as being safe or natural by people because it is a plant product," Scalzo said. "They don''t realize that over the last century, probably 25 percent of all our drugs are derived from plant sources. Even drugs like aspirin are derived from a plant."

There are many potential complications. A given dose may produce different effects in a 100-pound ballerina as opposed to a 350-pound football lineman. It may produce serious interactions with other supplements and drugs. It may produce serious complications in people with medical conditions they may not even know they have.

The substance is abused by drug dealers who buy large quantities of asthma and sinus medications containing ephedrine or pseudoephedrine to manufacture methamphetamine. Athletes reportedly use extra-large doses as a stimulant before games.

But even though the FDA verifies the dosage and effectiveness of these medications, Scalzo says consumers should be leery of taking them even as prescribed. The FDA currently recommends a maximum daily ephedrine dose of 24 milligrams, that supplements contain no more than 8 milligrams of ephedrine or related alkaloids per serving and that ephedrine be used for no longer than a week.

"There''s probably a lot better and safer products out there right now than to use ones with pseudoephedrine," Scalzo said. "Personally, I avoid them."

Last fall, Secretary of Health and Human Services Tommy Thompson asked the FDA to evaluate the scientific evidence and recommend the strongest possible mandatory warning label possible for ephedra products, but no action has yet been taken. Scalzo recommends that anyone who has an adverse reaction call the FDA''s Medwatch line at (800) 332-1088 or the national Poison Control Center hotline at (800) 222-1222.

Better yet, Mullins says, quit taking them or don''t buy them in the first place.

"There''s just no substitute for eating fewer calories and getting more exercise," he said. "If I were to put on an infomercial on TV right now, it would be ''No substitute for situps.''"