The Food and Drug Administration proposed new rules yesterday aimed at reducing the risks posed by a popular herbal stimulant that has been linked to seizures and deaths.

Products derived from herb ephedra are sold as an aid to weight loss and for a treatment of allergies, and they are popular among young people as pep pills. The stimulants are also called Ma huang, Chinese Ephedra and Epitonin, and are sold under such product names as Herbal Ecstasy and ULTIMATE Xphoria.

Since 1994, the FDA has received more than 800 reports of side effects from products made from ephedra, including irregular heartbeat, sleeplessness, anxiety, tremors and headaches. Extreme reactions have included seizures, heart attacks, strokes and two deaths. The FDA is looking at more than 15 other deaths that may have been caused by the products. Ephedra contains ephedrine, which is a stimulant.

"Often people think that because a product is called a dietary supplement, it does not have risks," said William B. Schultz, the FDA's deputy commissioner for policy. "But that is not necessarily true."

Under the proposed rules, manufacturers of products containing ephedrine alkaloids would have to limit the amount used to less than 8 milligrams per dose. Products would also be required to carry warning labels instructing consumers not to use more than 24 milligrams of the stimulant in any one day or to use the product for more than seven days.

Companies that want to market the products for their stimulant effects would be required to add a warning to the label that states: "Taking more than the recommended serving may result in heart attack, stroke, seizure or death."

The agency stopped short of attempting to ban the products, which are related to methamphetamine and are also similar to pseudoephedrine, the synthetic version used in over-the-counter decongestants.

The proposed regulations will appear in the Federal Register on Wednesday. The agency will receive written comments on the proposal until Aug. 18 and will issue a final regulation after reviewing the comments.

Industry reaction to the agency move was generally favorable. "We absolutely approve of the attempt to establish meaningful dose limits" on ephedra products, said spokesman Jeff Morrison of the American Herbal Products Association, which already had recommended dosage limits to its members.

Michael McGuffin, co-founder of Santa Monica, Calif.-based Zand Herbal Formulas, said he did not believe the FDA had enough evidence to block the supplement's use as a diet aid, and noted that the product has long been used in traditional Chinese medicine to fight nasal congestion. But, he added, that he did "not approve of the intentional sale of stimulants in any form as a way to get high."

The FDA move is "long overdue," said consumer advocate Bruce Silverglade of the Center for Science in the Public Interest. He noted that a 1994 law passed by Congress had "tied the agency's hands" when it came to regulating herbal products. The law loosened the agency's regulatory authority over dietary supplements, which historically have been held to lower standards of proof of safety and effectiveness than are drugs. The law, Silverglade said, "forces FDA to wait til there's blood on the tracks before the agency can act."

"One might ask," Silverglade said, "what are these products doing on the market at all?"

Schultz of the FDA said that the 1994 law did limit the agency's ability to act, but noted that the agency rarely used its broader authority in the past. "If the rules are going to put the responsibility on the consumers, as this law does, people have to realize that they have to take it seriously and become informed and make intelligent decisions," Schultz said.

One satisfied ephedra customer said that he was happy that the FDA had not tried to ban the product. Michael Feddersen, a Beverly Hills, Calif., interior designer, said that he uses the product to manage his hay fever, and finds that it works better than drugs. "When you really have a problem and you're really draining like crazy, it's really incredibly effective," he said. But Karen Schlendorf of Northport, N.Y., whose 20-year-old son, Peter, died last March after taking the drug during spring break, said she was "glad they decided to do something. In my heart, I wish it were a little more." Better warning labels might mean that "maybe we can save a life," Schlendorf said. "I know my son would never have taken this stuff if he'd realized how dangerous it was."

"It's a very bitter pill to swallow," Schlendorf said. "Trying to make money was more important . . . than saving the life of one person, whether it was my son or someone else."