Background: Acanthosis nigricans is commonly associated with obesity. It is characterized by brown-black skin thickening on the neck and the flexural areas. This study aimed to assess the efficacy of topical 20% urea cream compared to 10% urea cream in the treatment of acanthosis nigricans in adolescents.

Material and methods: A randomized comparative, double-blind study was conducted on participants aged 12-18 years with acanthosis nigricans of the neck. Treatment efficacy was assessed via narrowband reflectance spectrophotometer, while the overall success rates at weeks 2, 4, and 8 were evaluated by the investigator- and participant-assessed global evaluation scales.

Results: A total of 40 participants with acanthosis nigricans were enrolled and completed the study. Throughout the period of 8 weeks of treatment, 20% urea showed greater improvement of hyperpigmentation compared to 10% urea (p = 0.001), with 22.5 ± 11.9% and 10.7 ± 8.1% improvements, respectively. Findings from the overall global evaluation scales were consistent with the results from the narrowband reflectance spectrophotometer. Treatment with 10% urea and 20% urea was well-tolerated without any local serious adverse reactions.

Conclusion: Urea cream improves neck hyperpigmentation associated with acanthosis nigricans in adolescents, in which the 20% concentration shows superior efficacy to the 10% concentration.