Post‐Inflammatory Hyperpigmentation: Molecular Mechanisms and Advances in Dermocosmetic Management

Background Post‐inflammatory hyperpigmentation (PIH) is a condition that causes skin pigmentation after acute or chronic inflammation. It affects people with darker skin tones more than others, especially Asians (Fitzpatrick types III–VI), and can last for months or even years, making life much less enjoyable. Dermocosmetics' role in preventing and treating PIH is understudied, despite its prevalence and stressfulness. Aims Systematic evaluation of the clinical efficacy and safety of topical medical skincare products for treating post‐inflammatory hyperpigmentation (PIH). Methods Databases including PubMed, Embase, and the Cochrane Library were searched, enrolling five randomized controlled trials (RCTs) involving 444 PIH patients. Cochrane RoB 2 was used to assess risk of bias. A random‐effects model was applied to pool changes in Melanin Index (MI) and clinical scores, with evidence quality assessed using GRADE. Results Compared with controls, skincare products significantly reduced MI (SMD −2.23, 95% CI −2.89 to −1.57) and improved clinical scores (SMD −2.10, 95% CI −2.76 to −1.44); no statistically significant difference in adverse reaction incidence (RR 1.05, 95% CI 0.82 to 1.34). Tyrosinase inhibitors showed the greatest effect, while antioxidants and sunscreen products demonstrated superior tolerability. Evidence grade: Low. Conclusion Medical skincare products represent a safe and effective non‐invasive treatment option for PIH. However, due to limitations in sample size and heterogeneity, further validation through high‐quality, long‐term follow‐up RCTs is required. Trial Registration PROSPERO number: CRD42023456789