"Unknown Risks" of non-steroid topical medications for atopic dermatitis

Tacrolimus ointment is a nonsteroid treatment for atopic dermatitis which is both effective and has a minimal side-effect profile. However, some clinicians may be reluctant to use tacrolimus ointment due to the "unknown risks", meaning those that have not been uncovered in human studies conducted thus far. Therefore, the available animal data regarding the "unknown risks" of topical tacrolimus therapy are reviewed, and a discussion of the interpretation of this available but limited data is presented.

Some of the fear on the part of clinicians regarding the use of topical tacrolimus may come from the results of animal studies which showed an increase in lymphoma and UV-induced skin cancer after treatment with topical tacrolimus in animal models of carcinogenesis. However, rigorous assessment of these studies suggest that it is somewhat likely that these represent a species-specific response to tacrolimus in an animal already predisposed to tumor formation, and therefore may not be relevant in assessing the possibility of an increased human health risk.

Animal and human studies suggest that topical tacrolimus is a safe alternative to topical steroids, with the major known adverse effect being a transient burning sensation, compared with the known adverse effects of topical steroids, including long-lasting ones. Therefore, in the opinion of the authors, currently available data, including animal studies, does not suggest that "unknown risks" of topical tacrolimus need be any more concerning than the known side-effects of the topical steroids.