The Food and Drug Administration yesterday told distributors and manufacturers of a hormone sold nationwide for weight reduction to quit selling the product, saying it has not been reviewed for safety and effectiveness.

The FDA took the action against a steroidal hormone called DHEA, or dehydroepiandrosterone or dehydroandrosterone, which has been marketed through retail stores and by mail order as a product that can promote weight loss, a better sex life and longer life span.

FDA spokesman Bruce Brown said the agency is aware of 17 manufacturers selling the substance "from New York to California to Florida, and in between," but added that there easily could be other manufacturers. Most call their products DHEA or DHEA-complex, he said.

Brown said DHEA is undergoing scientific testing in animals at Temple University and at the private Jackson Laboratory in Bar Harbor, Maine, to determine if it may have some medical use in weight control or cancer treatment.

However, he said, the substance is far from being ready for human use. If it is later approved for medical treatment, it likely will be a prescription drug because of the chance of side effects, Brown added.

Brown said the possibility of side effects concerns FDA. To avoid them, the products sold now probably "either do not contain DHEA or they contain clinically insignificant amounts," he said.