The labels on two prescription creams to treat eczema will have to bear "black box" warnings of possible cancer risks. The Food and Drug Administration action follows an agency advisory committee recommendation last February that Elidel cream and Protopic ointment carries the label warnings.

The new labeling also will clarify that the two drugs are recommended for use only after other prescription topical medicines have been tried by patients, the FDA said. The agency is also issuing a guide updating patients of its concerns.

A black box warning is the most serious type of warning in prescription drug labeling. The warning will be located lower on the labels of the two drugs than is typical, although a statement higher on the labels will refer to the risk.

Eczema is a medical condition that causes the skin to become inflamed or irritated. It affects 10 to 20 percent of infants and about three percent of adults and children in the U.S.

Novartis Pharmaceuticals, which makes Elidel, says in a statement Thursday that it remained confident in the safety and efficacy of Elidel.

Astellas Pharma Inc., formed through the merger of Protopic maker Fujisawa Healthcare Inc. and Yamanouchi Pharmaceutical Co., says in a statement that its drug "is safe and effective when used in a manner consistent with its label."