The cholesterol drug Crestor (search) is being relabeled to add a warning that starter doses should be reduced in Asian-Americans and some other patients.

The Food and Drug Administration said Wednesday that Crestor, like other drugs in the category known as statins, can have a rare side effect of serious muscle damage.

A clinical trial found that levels of Crestor in Asian patients were double those of Caucasians taking the same dose, increasing the chance of muscle damage.

The new label urges physicians to start Asian patients, those with severe kidney disease and patients taking cyclosporine at the lowest dose level.

The lowest available dose would be 5 milligrams, compared with a maximum dose of 40 milligrams.

The cholesterol-lowering drug has been prescribed to more than 4.3 million patients, according to manufacturer AstraZeneca.

"We continue to believe Crestor is safe and effective when used according to the prescribing information," said David Brennan, AstraZeneca president.

Dr. Steven Galson, acting director of the FDA's Center for Drug Evaluation and Research, said the "advisory on Crestor is part of an ongoing effort to notify the public of potentially significant emerging safety data so that they can make more informed choices about their medical care."

Crestor has drawn some criticism for the reported muscle damage, but the FDA statement said a review of available data indicates the risk from Crestor is no higher than that from other statin drugs.

The FDA noted that kidney failure has also been reported in patients treated with Crestor and other statins. However, the agency said, since many patients who take these drugs have diabetes, high blood pressure or heart disease, they may already be at higher risk for kidney failure.

Overall, the FDA said it believes the benefits of statin drugs, when used as recommended, outweigh their potential risks.

Crestor has drawn criticism from consumer advocate Dr. Sidney Wolfe of Public Citizen as well as FDA whistleblower David Graham. In December the manufacturer said it had halted ads for the drug that the FDA criticized as misleading because they suggested Crestor is safer than has been proven.