Topical treatment for postinflammatory hyperpigmentation: a systematic review

Background Topical measures are the mainstay treatment for postinflammatory hyperpigmentation (PIH). Numerous studies have assessed the efficacy of topical medications for the treatment of PIH, but few have evaluated the quality of evidence supporting these topical therapies. We performed a systematic review to evaluate the evidence of topical treatments for PIH.Methods We included English-language studies that evaluated topical medications for PIH. We searched PubMed, MEDLINE, and EMBASE from conception to March 29 2021. We used the modified Grading of Recommendations, Assessment, Development and Evaluation scale (GRADE) scale to assess quality of evidence.Results Forty-seven of 1,224 studies with 1,853 subjects were included. Topical agents with high-quality studies included retinoids, hydroxy acids, corticosteroids, thiamidol, niacinamide and plant-derived products. Sunscreens with SPF30 or greater was recommended in almost every study. Common side effects included desquamation, burning, stinging, dryness, and pruritus.Conclusions Retinoids, hydroxy acids and broad-spectrum sunscreen were supported by the greatest number of high-quality studies. Ongoing inflammation may be subtle, especially in darker skin phenotypes. Herein, we proposed an evidence-based algorithm for PIH based on the high-quality studies. There is a need to adopt a validated outcome measure for PIH to better compare efficacy between various treatments in future studies.