Comparative efficacy and safety of fractional carbon dioxide and erbium-based fractional lasers for atrophic acne scars: A systematic review and meta-analysis.

Fractional laser resurfacing is widely used for atrophic acne scars, but the comparative efficacy and tolerability of fractional carbon dioxide (CO₂) and erbium-based fractional lasers remain uncertain because of heterogeneous outcome definitions and laser platforms. This systematic review and meta-analysis aimed to compare the clinical response, safety, and recovery profiles of fractional CO₂ and erbium-based fractional lasers for atrophic acne scars. PubMed, Embase, Web of Science, and the Cochrane Library were searched from inception to April 2026. Comparative clinical studies evaluating fractional CO₂ lasers versus erbium: yttrium-aluminum-garnet (Er: YAG) or erbium-glass fractional lasers were included. Clinical response > 50% improvement was harmonized as the primary efficacy outcome. Relative risks (RRs), mean differences (MDs), and odds ratios (ORs) were pooled with 95% confidence intervals (CIs). Five studies involving 130 analyzed participants were included. Four studies contributed to the primary efficacy analysis. Erbium-based lasers were associated with a lower probability of > 50% clinical response than fractional CO₂ laser (RR, 0.69; 95% CI, 0.49-0.97; I²=45.9%). In the randomized-only sensitivity analysis, the direction was maintained but the CI included the null (RR, 0.76; 95% CI, 0.54-1.08). Fractional CO₂ laser was associated with greater treatment-related pain (MD, 1.86; 95% CI, 1.33-2.39) and longer downtime (MD, 3.67 days; 95% CI, 1.90-5.44). No statistically significant differences were observed for post-inflammatory hyperpigmentation (OR, 1.75; 95% CI, 0.67-4.57) or acneiform events (OR, 0.73; 95% CI, 0.12-4.25). Available comparative evidence suggests a favorable clinical-response signal for fractional CO₂ laser, accompanied by greater procedural pain and longer recovery. Treatment selection should therefore balance expected scar improvement against tolerability and downtime.