The Influence of Urea Treatment on Skin Susceptibility to Surfactant-Induced Irritation: A Placebo-Controlled and Randomized Study

Certain ingredients in moisturizing creams may influence the skin susceptibility to irritants. One agent of particular interest is the well-known humectant urea. The present placebo-controlled study on 28 subjects was designed to evaluate the effects of urea treatment on three types of sodium lauryl sulphate (SLS) exposures: (1) repeated exposure to SLS for 15 days with concurrent cream treatment, (2) the skin susceptibility to SLS following prophylactic treatment with urea and (3) SLS exposure after recovery of the surfactant-damaged skin by urea treatment. Parameters measured were transepidermal water loss (TEWL) and skin blood flow. Repeated exposure to SLS induced a slight but significant barrier damage, measured as TEWL, and the difference between the treatments was almost significant (p = 0.06). Treatment of normal skin reduced TEWL in the urea-treated area, and the irritant reaction to SLS was significantly decreased. Treatment of surfactant-damaged skin promoted barrier recovery, and the second exposure to SLS induced a less pronounced reaction in the urea-treated area compared to the placebo-treated site. In conclusion, urea promotes barrier recovery in SLS-damaged skin and makes both normal and irritated skin less susceptible to irritation. The findings may be of clinical relevance in attempts to reduce contact dermatitis due to irritant stimuli.