IMPORTANCE Lasers are gaining interest as a treatment option for postinflammatory hyperpigmentation (PIH) but can pose a clinical dilemma given the risk for laser-induced or exacerbated PIH. OBJECTIVE To assess the clinical evidence for the use of lasers in the treatment of PIH. EVIDENCE REVIEW A systematic review was performed by searching PubMed databases from January 1, 1990, through May 31, 2016. Included studies involved laser treatment for PIH with the degree of pigmentation as a measure of outcome. The search was filtered to include only clinical studies written in the English language. Study methods were analyzed and the reproducibility of the studies was graded. Outcome measures varied from study to study and included concentration of melanin and hemoglobin, patient satisfaction questionnaires, clinical photography, subjective clinical improvement, light microscopy, melanin index, reflectance spectroscopy, and/or skin biopsy evaluated by a blinded dermatopathologist. FINDINGS Of 1295 results, 20 unique studies with 224 patients met the inclusion criteria. These studies included 1 randomized clinical observer-blinded study (6 patients), 4 nonrandomized clinical trials (133 patients), 1 cohort study (34 patients), 7 case series (44 patients), and 7 case reports (7 patients). Multiple lasers were studied; however,most of the studies were not methodologically rigorous. Some studies showed no improvement or worsening of PIH after laser treatment. The most extensively studied device was the Q-switched Nd:YAG laser, which has shown promising results based on multiple outcome measures as listed above. CONCLUSIONS AND RELEVANCE Some lasers may be beneficial in the treatment of PIH. The evidence suggests that additional studies would be required to determine the benefit of laser treatment of PIH.
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