Johnson & Johnson’s foot gel, Regranex 0.01% (becaplermin), used to treat refractory legs and foot ulcers that are not healing in diabetic patients, will carry from now on a “black-box,” warning users on the increased risk of dying from cancer, the U.S. Food and Drug Administration said Friday.

The FDA decision follows results of a postmarket epidemiologic study involving 4431 patients, 1,622 of whom were exposed to Regranex and 2,809 were controls. The study, announced in early March, found that the patients treated with more than three tubes of the cream over two years had a five time bigger risk of developing cancer.

Susan Walker, M.D., director of the Division of Dermatological and Dental Products, said the FDA “still cautions health care professionals to carefully weigh the risks and benefits of treating patients with Regranex,” adding that the drug is not recommended for patients with known malignancies.

Foot ulcers are the leading causes for hospitalization of patients with diabetes. Regranex is an artificial version of a substance from the growth factor category that is created by the human body, which makes cells divide more rapidly than usual. When combined with wound care products, Regranex helps wounds heal faster.

In response the to the FDA decision, Johnson & Johnson’s Ethicon unit, which sells Regranex, said the risk of a patient using the gel to develop cancer is minimal if taking into consideration that only four cases of cancer were reported while, in the past ten years, the gel was used by more than 750,000 patients.

“We remain confident in the safety and efficacy of Regranex Gel when used according to its label,” James Hart, Ethicon’s vice president for global medical affairs said in a statement, according to Reuters.