Efficacy of Compound Acid Chemical Peeling in Patients with Moderate Acne: A Prospective Study with Comprehensive Facial Evaluation.

Compound acid chemical peeling is widely used to treat acne vulgaris (AV), but the biological mechanisms underlying its clinical effects remain incompletely understood. We hypothesized that compound acid chemical peeling would improve acne severity and would be associated with changes in the skin microbiome and a reduction in local inflammatory responses in patients with moderate AV. This study aimed to investigate the clinical, microbiological, and inflammatory effects of compound acid peeling in this population. We carried out a prospective, split‑face, randomized trial enrolling 30 patients with moderate AV. One hemiface received compound acid peeling twice weekly for 3 weeks (6 total sessions), followed by a 9‑week observation period. The contralateral hemiface received no treatment for the first 3 weeks and then underwent the same peeling protocol for 3 weeks, with a 6‑week follow‑up. Outcome measures included the Global Acne Grading System (GAGS), patient self‑assessment, standardized facial imaging, skin biopsy with immunohistochemistry, bacterial DNA extraction, PCR amplification, and 16S rRNA gene sequencing. Patients showed a statistically significant improvement in GAGS scores (P < 0.001). Facial imaging analysis revealed reductions in redness and porphyrin readings. Immunohistochemical staining for interleukin (IL)-1α, IL-6, IL-17, transforming growth factor-β (TGF-β), and toll-like receptor 2 (TLR2) was reduced. Skin microbiome alpha diversity decreased, with a notable decrease in the relative abundance of Staphylococcus (P < 0.05). Throughout the study, no adverse events were reported. Compound acid peeling was effective and well-tolerated during the observation period and was associated with changes in the skin microbiome and local inflammatory marker staining.