Our understanding of the details of the recovery time of acute irritant contact dermatitis (ICD) is limited. We examined skin reactivity to a model surfactant, sodium lauryl sulfate (SLS), on previous acute ICD and normal sites over time with visual grading and noninvasive instruments. Acute ICD was induced on the upper arms of 18 volunteers (aged 30 to 51 years) by occluded application of 1% SLS for 24 h. Previous ICD and normal sites were provoked by occluded application of 2% or 7.5% SLS 30 min daily 4 consecutive days. Skin reactivity was assessed daily by visual erythema scoring (VES), transepidermal water loss (TEWL), skin color reflectance (SCR) and electrical capacitance (EC). Skin function of previous ICD sites assessed by VES, TEWL, SCR, and EC did not normalize until 2 weeks later; all parameters of previous ICD returned to normal after 3 weeks. While skin reactivity to 2% and 7.5% SLS showed no differences between previous ICD and normal sites at 4 weeks, differences of irritant reactivity especially 7.5% SLS between previous ICD and normal sites were significant at 3 weeks post-provocation. Our results demonstrate that irritation evaluated with irritant provocation was long-lasting, even though skin functional parameters assessed by various bioengineering instruments returned to normal. Complete recovery of skin function including irritability after acute ICD induced by 1% SLS was achieved approximately 4 weeks later. The date were generated with a model surfactant; it remains to be determined whether similar responses will be noted with chemicals of different physiochemical properties.