Washington ? 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 Thursday follows an agency advisory committee recommendation last year that Elidel cream and Protopic ointment carry 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.

As of October, the FDA has received reports of 78 cases of cancers in patients treated with the two drugs.

Novartis Pharmaceuticals makes Elidel, and Astellas Pharma Inc. produces Protopic. They estimate about 10 million people combined have used the drugs.