摘要： The authors conducted this meta-analysis of randomized controlled trials (RCTs) to assess the effects of photobiomodulation therapy (PBMT) in the treatment of androgenic alopecia (AA). RCTs published in Pubmed, Web of Science, and Embase were systematically reviewed to identify the effects of PBMT in AA patients. The outcome measures included hair density and hair growth. Results were expressed as weighted mean difference (WMD) with 95% confidence interval (95%CI) and a risk ratio (RR) of 95%CI. A fixed-effects model or a randomized-effects model was performed according to the heterogeneity among the included studies. Nine RCTs met the inclusion criteria and were included in this meta-analysis. The mean change from baseline in hair density was 36.78 ± 23.84/cm2 in the PBMT group as compared with 8.88 ± 19.56/cm2 in the control group. Patients who received PBMT had a greater increase in hair density than those treated with a sham device (WMD = 18.56/cm2, 95%CI: 13.22, 23.89; P < 0.001). Moreover, PBMT was associated with a 42.43% increase in hair growth as compared with the sham device treatment (WMD = 42.43, 95%CI: 28.58, 56.28; P < 0.001). A greater rate of patients who were treated with PBMT achieved an improvement in hair regrowth than those with the sham device (RR = 1.32, 95%CI: 1.09, 1.58; P = 0.003). This study indicated that PBMT seemed to be a promising noninvasive treatment for patients with AA since it could improve hair density and stimulate hair growth. However, considering the potential limitations in this study, more large-scale RCTs are needed to verify our findings.