U.S. poison control centers reported 1,178 adverse reactions to ephedra dietary supplements in 2001, said the study, which was to be posted on the Annals of Internal Medicine's Web site Tuesday and published in the journal next month.
Ephedra accounted for 64 percent of all adverse reactions involving herbs, even though it is found in fewer than 1 percent of all herbal products sold.
"It comes down to a risk-benefit ratio," said one of the report's authors, Dr. Stephen Bent of the San Francisco Veterans Affairs Medical Center. "The benefits for ephedra are not at all well established. It is a minimal benefit that goes away when you stop using the product. And the risks are really substantial."
The study, based on data collected by the American Association of Poison Control Centers, is just the latest to question ephedra's safety.
The Food and Drug Administration has reports of nearly 100 deaths of people who had taken the herb, a stimulant that can quicken a person's heart rate and cause their blood vessels to constrict.
The American Medical Association has also advised people not to use ephedra, which has been banned by the International Olympic Committee, the National Football League and the National Collegiate Athletic Association.
The Bush administration ordered a review of ephedra's safety in June.
Wes Seigner, a lawyer for the Ephedra Education Council, a group funded by the supplement industry, insisted the herb can be used safely.
He noted that the study compared ephedra only to other herbs, including such mild agents as ginseng and St. John's wort, and not to medications used by people trying to lose weight.
The study also didn't explore the seriousness of the reactions reported to poison centers, Seigner said. Some of the reported side effects could be as benign as a headache, he said.
Seigner said that while the industry generally agrees that ephedra supplements should come with a mandatory warning label and shouldn't be marketed to children, banning them would be to ignore a potential treatment for obesity.
Ephedra, also known by its Chinese name, Ma huang, was once widely used in the United States as a decongestant and asthma treatment. Doctors stopped prescribing it in the 1930s in favor of safer medications.
Now it shows up most in "performance enhancing" dietary supplements marketed to athletes.
An Alabama jury last year ordered supplement maker Metabolife International to pay $4.1 million to four people who suffered strokes or heart attacks after taking an ephedra-based appetite suppressant. And the families of a dead 28-year-old bodybuilder in Las Vegas and a dead 27-year-old Marine Corps officer in Florida sued supplement-maker Twin Laboratories Inc. blaming the deaths on an ephedra supplement called "Ripped Fuel."
By David B. Caruso