The U.S. Food and Drug Administration sent out a warning to consumers not to use off-brand versions Ozempic and Wegovy to lose weight.

The trouble is that those versions, often sold online, contain a version of semaglutide that is used in lab research and has not been approved for use in people.

“Compounded drugs are not FDA-approved, and the agency does not verify the safety or effectiveness of compounded drugs,” the notice said.

The drugs are being taken by many as a weigh-loss drug. Wegovy is a prescription for overweight or obese patients, and ozempic is a medication for those with type 2 diabetes.

Regulators warn the off brands might not contain the same ingredients as the prescription products and may not be safe or effective.

The Associated Press contributed to this report.