Two eczema creams - Novartis’s Elidel and Fujisawa’s Protopic - must carry a strong warning of cancer risk, the U.S. Food and Drug Administration said on Thursday.

Research shows the creams are absorbed into the body and can cause cancer, the FDA said. The creams will carry a “black box” warning - the strongest warning carried on medicines.

And babies should not be treated with the creams at all, the FDA said.

“The data showed that the risk of cancer increased as the amount of the drug given increased. The data also included a small number of reports of cancers in children and adults treated with Elidel or Protopic,” the FDA said in a statement.

In February members of an FDA advisory panel said they were concerned the companies were aggressively advertising the medicines to treat infants and others with skin problems the creams are not approved to treat.

Elidel, known generically as pimecrolimus, and Protopic known generically as tacrolimus, should be used only as directed and only after other eczema treatments have failed to work because of the risk, the FDA said.

Since the FDA approved Protopic in 2000 and Elidel in 2001, seven cases of lymphoma and six skin cancer cases have been reported in patients, the FDA said.

Animal tests have suggested the creams could cause cancer, the FDA added.

“The manufacturers of the products have agreed to conduct research to determine whether there is an actual risk of cancer in humans, and, if so, its extent,” the FDA said.

“Both products are applied to the skin to control eczema by suppressing the immune system. FDA’s Public Health Advisory specifically advises physicians to weigh the risks and benefits of these drugs in adults and children,” the agency added.

Doctors who prescribe the drugs should remember they should be used only for the shortest time possible, it said.

“Elidel and Protopic are not approved for use in children younger than 2 years old,” the FDA added.

“The long-term effect of Elidel and Protopic on the developing immune system in infants and children is not known. In clinical trials, infants and children younger than 2 years of age treated with Elidel had a higher rate of upper respiratory infections than those treated with placebo cream.”

According to the National Institutes of Health (NIH), about 15 million Americans, including about 20 percent of children, suffer from eczema, a skin inflammation that can cause itchy thick skin with blisters or scaly patches.