RESUMEN
This study aimed to evaluate the effectiveness of isolated treatment with retinoic acid and its combination with the microneedling technique in facial melasma, seeking to associate these results with possible oxidative damage. This is a blinded randomized clinical trial with 42 women with facial melasma (skin phototype I-IV), randomized into Group A (microneedling and 5% retinoic acid) or Group B (5% retinoic acid alone). Four procedures were applied with 15 days intervals (4 blood collections). Clinical improvement was assessed using the Melasma Area Severity Index (MASI). Serum oxidative stress levels were evaluated by protein oxidation (carbonyl), lipid peroxidation (TBARS) and sulfhydryl groups, as well as enzyme activities of superoxide dismutase (SOD) and catalase (CAT). The statistical analyzes were performed by generalized estimation equation (GEE). There was a reduction in MASI scale and TBARS levels in both groups over time (p < 0.05), with no difference between groups (p = 0.416). There was also a substantial increase in the carbonyl levels at 30 days (p = 0.002). The SOD activity decreased after 30 days, regardless of group (p < 0.001), which was maintained after 60 days. In Group A, there was a reduction in sulfhydryl levels at 60 days (p < 0.001). It is important to highlight that both groups demonstrated efficacy in the clinical improvement of melasma within at least 60 days, reducing the MASI score by almost 50%. However, microneedling with retinoic acid seems to be the worst treatment because there is a reduction in the non-enzymatic antioxidant defense, which is important to protect against oxidative stress.