Post-summertime exacerbation of acne is not a rare event. This study was conducted to assess the preventive effect of a proprietary formulation containing 2-hydroxy-5-octanoyl benzoic acid on this environmental related disease. This compound is commonly called beta-lipohydroxyacid (LHA). Among a randomized group of 14 acne-prone women, 12 who developed cornified follicular plugs the end of summertime were treated by the LHA formulation twice daily for 2 weeks. Ten of 14 other women who presented the same skin condition remained untreated as controls. The comedolytic effect was assessed using non-invasive ultraviolet-light video recording combined with computerized image analysis. The cornified follicular plugs were progressively cleared in 10/12 LHA-treated women and in 3/10 untreated volunteers. Analytical assessments showed a significant decrease in both the number and total size of microcomedones in the LHA-treated women. By contrast, no quantitative change was disclosed in the untreated group. It is concluded that the tested LHA formulation exerts comedolytic properties that might help in preventing post-summertime acne exacerbations.