WASHINGTON – Government health officials warned dieters and body builders Friday to immediately stop using Hydroxycut, a widely sold supplement linked to cases of serious liver damage and at least one death.

The Food and Drug Administration said the maker of the dietary supplement has agreed to recall 14 Hydroxycut products. Available in grocery stores and pharmacies, Hydroxycut is advertised as made from natural ingredients. At least 9 million packages were sold last year, the FDA said.

Dr. Linda Katz of the FDA’s food and nutrition division said the agency has received 23 reports of liver problems, including the death of a 19-year-old boy living in the Southwest. The teenager died in 2007, and the death was reported to the FDA this March.

Other patients experienced symptoms ranging from jaundice, or yellowing of the skin, to liver failure. One received a transplant and another was placed on a list to await a new liver.

There was no immediate comment from the U.S. distributor of the diet pill, Iovate Health Sciences, headquartered near Buffalo, N.Y. Made by a Canadian company, Hydroxycut is used by people trying to shed pounds and by body builders to sharpen their muscles.

Dietary supplements aren’t as tightly regulated by the government as medications. Manufacturers don’t need to prove to the FDA that their products are safe and effective before they can sell them to consumers. But regulators monitor aftermarket reports for signs of trouble, and in recent years companies have been put under stricter requirements to alert the FDA when they learn of problems.

Katz said it has taken so long to get a handle on the Hydroxycut problem because the cases of liver damage were rare and the FDA has no authority to review supplements before they’re marketed. “Part of the problem is that the FDA looks at dietary supplements from a post-market perspective, and an isolated incident is often difficult to follow,” she said.

The FDA relies on voluntary reports to detect such problems, and many cases are never reported, officials acknowledge.

Health officials said they have been unable to determine which Hydroxycut ingredients are potentially toxic, partially because the formulation of the products has changed several times. A medical journal report last month raised questions about one ingredient, hydroxycitric acid, derived from a tropical fruit. The article said it could potentially damage the liver.