BACKGROUND: Vitiligo is a commonly acquired autoimmune pigmentary disorder. Some patients resist conventional treatments, leading to the search for combination therapies. AIMS: This study aimed to compare the efficacy of 308-nm excimer laser monotherapy versus combined treatment with topical bimatoprost 0.03% in patients with facial vitiligo. PATIENTS AND METHODS: A single-blind randomized clinical trial was conducted at Razi Hospital, Tehran, on 38 patients with facial vitiligo who had at least one facial vitiligo patch and had not undergone treatment in the past 3 months. The patients were randomly allocated to either the intervention group (n = 18) or the control group (n = 20). Both groups received 308-nm EL therapy twice weekly for 15 weeks, while the intervention group additionally applied 0.03% bimatoprost solution daily. The patients were visited at the end of every 5 weeks and after the 15th week. Efficacy was evaluated using the scale for improvement assessment (SAI), visual analog scale satisfaction (VASS), and visual analog scale improvement (VASI). Data analysis was performed using the Mann-Whitney and t-tests, with a significance level set at p <
0.05. RESULTS: Of the total patients, 27 (71.05%) were female and 11 (28.95%) were male. The male-to-female ratio was 50% in the intervention group and 33.33% in the control group. The mean VASI score, as the primary outcome, showed a significant increase over time in the intervention group (p ≤ 0.001), increasing from 4.53 to 7.20 (an increase of 2.67 units). Additionally, the intervention had a significant effect on the VASI outcome compared to the control (p ≤ 0.001
mean difference: 2.55 [1.63 to 3.47]). As the secondary outcomes, the mean VASS and SAI scores significantly decreased over time in the intervention group (p ≤ 0.05). The intervention also significantly affected the VASS and SAI outcomes compared to the control (p ≤ 0.001). The side effects of the intervention group were hypertrichosis in three patients and erythema burning in one patient. CONCLUSIONS: Adding bimatoprost 0.03% to the treatment regimen may improve the outcomes of patients with facial vitiligo who are resistant to conventional treatments.