The use of urea for the treatment of onychomycosis: a systematic review

BACKGROUND: Onychomycosis, a fungal infection affecting the nail plate, is a common condition often requiring prolonged treatment regimens, with low success rates. Urea is one treatment option, which is thought to improve the efficacy of topical and oral antifungal agents. Despite a theoretical basis for the use of urea for the treatment of onychomycosis, the evidence-base for this treatment has not been systematically reviewed. AIM: The purpose of this study was to conduct a systematic literature review to determine the efficacy and safety of urea as a monotherapy and as adjunct therapy, compared to other treatment regimens for onychomycosis. METHOD: A systematic literature search of ten electronic databases was conducted. Only studies that used microscopy and culture or other validated laboratory-based testing method to confirm the presence of a fungal infection before treatment were included. The outcome measures assessed were efficacy (defined in terms of mycological, clinical and complete cure) and safety (defined as self-reported adverse events). RESULTS: The systematic search yielded 560 unique studies for review. Of these, only six were eligible for inclusion. All studies were observed to have methodological concerns, most studies consisted of small sample sizes and were difficult to compare given heterogeneity in outcome measures and follow-up time. Despite this, a trend was observed to suggest that urea, when added to topical or oral antifungal treatment regimens, improved efficacy of the treatment. CONCLUSION: This review suggests that topical urea, as an adjunct to topical and oral antifungal treatment regimens, may improve the efficacy of treatment. However, further research is needed. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13047-019-0332-3) contains supplementary material, which is available to authorized users.