The U.S. Food and Drug Administration (FDA) on Tuesday warned against the use of allergy drug that contain promethazine hydrochloride (HCL) to children less than two years old.

The U.S. drug safety watchdog said in a safety alert that cases of breathing problems, some causing death, have been reported to it, when the drug was used in children under age 2.

The allergy drug, approved in 1951, is marketed as Phenergan as well as in various generic versions. The FDA warnings apply to all forms of the drug, including syrups, suppositories, tablets and injectables.

The FDA said labels on all versions of the drug have made changes corresponding to the strengthened warnings. It also asked parents to be cautious in giving the drug to children older than 2.

Source: Xinhua