Efficacy of topical vitamin C in melasma and photoaging: A systematic review.

BACKGROUND: Vitamin C is a micronutrient present in high concentrations in normal skin and a highly prescribed cosmeceutical, well known for protecting against ultraviolet-induced pigmentation and regulating collagen production. However, there is a lack of studies evaluating the efficacy of topical vitamin C in photoaging and melasma, with this systematic review being the first to assess the existing evidence. AIM: This systematic review aims to assess whether topical vitamin C could be effective in reversing photoaging signs and treating melasma. METHODS: Prospective, randomized controlled trials assessing protocols with topically applied vitamin C in patients with melasma or photodamage were searched in Medline, CENTRAL, and Scopus databases until the 12th of May 2022. Risk of bias was conducted in accordance with Cochrane Collaboration's tool for assessing the risk of bias in randomized trials, using RevMan 5.0. RESULTS: Seven publications were included, with 139 volunteers in total. Studies that evaluated the topography of skin indicated that the treated skin appeared smoother and less wrinkled, which was supported by biopsies data. On objective assessments of pigmentation, there was a significant lightening of the skin treated. Hydration improved equally in the vitamin C and placebo-treated sites. CONCLUSIONS: This study revealed that vitamin C is effective in treating uneven, wrinkled skin and has depigmenting properties, but long-term use may be needed to achieve noticeable changes. Q-switched Nd:YAG laser-associated protocols appear beneficial in enhancing vitamin C effects. Topical vitamin C may be a suitable alternative for melasma and photoaging, but more studies are needed to confirm these results and assess the ideal vitamin C concentration.