Patients with rosacea form a unique subset of the sensitive skin population because of the barrier defects inherent in this condition and the increased propensity for burning/stinging from topical products. This propensity for burning/ stinging when medications, skin care products, or cosmetics are applied to the facial skin has been frequently documented but never quantified. The objective of this 2-week study was to determine the prevalence of heightened neurosensory perceptions of burning/stinging in a random population of 40 women with mild to moderate rosacea defined as 15 or fewer inflammatory papules or pustules. Also evaluated was the effect of azelaic acid 15% gel on barrier function and facial stinging utilizing transepidermal water loss (TEWL), corneometry, and lactic acid facial sting tests as noninvasive measurement criteria. At baseline, the incidence of lactic acid stinging among these rosacea subjects was 62.5%, which is substantially higher than observed in the general population. Two weeks after application of azelaic acid 15% gel, no evidence of barrier damage was noted on TEWL or corneometry tests. Moreover, there was no statistical relationship between lactic acid stinging and a stinging response that is occasionally reported with exposure to azelaic acid 15% gel.