Efficacy of Botulinum Toxin A for the Management of Melasma: A Split‐Face, Randomized Control Study

Background Melasma management remains challenging due to its multifactorial nature pathogenesis and recurrent nature. Previous studies showed positive effects of botulinum toxin A (BoNT‐A) for treating and preventing ultraviolet‐induced hyperpigmentation. Objective To evaluate the effectiveness of adjunctive incoBoNT‐A injection combined with triple combination cream (TCC, 4% hydroquinone, 0.05% tretinoin, and 0.01% fluocinolone acetonide) for treating and preventing melasma recurrence compared to topical therapy alone. Methods A split‐face study was conducted in 30 female patients with melasma. One side of the face was randomly applied TCC to the melasma‐affected areas for 12 weeks (monotherapy), while the contralateral side received TCC and intradermal incoBoNT‐A at baseline and week 12 (combination therapy side). Evaluations were performed at baseline and 2, 4, 8, 12, 16, 20, and 24 weeks. Clinical improvement and melanin index were assessed using the MASI score on the malar area (MASI m ), and Colorimeter respectively. Patient satisfaction was also evaluated. Results Twenty‐eight subjects completed the study. The combination therapy side showed significant MASI m decrease at week 2 ( p = 0.0032), while the monotherapy side showed no significant change. At 4 weeks, a greater reduction of MASI m was observed in the combination therapy side (MASI m 14.5 and 11.54, 20.41% reduction) when compared to the monotherapy side (MASI m 11.68 and 11.79, 0.93% worsening). At week 12, worsening of melasma was observed on both sides during the summer period. At week 24 (3 months after discontinuing TCC), MASI m was 14.79 on the monotherapy side (worsen 21.03% from baseline) and 9.14 on the combined technique (36.97% improvement, p = 0.0003). Patients' satisfaction was higher for the combination therapy when compared to the monotherapy at the end of the study (8.92 vs. 7.04, p < 0.0001). No serious adverse events occurred. Conclusion Intradermal incoBoNT‐A injection combined with TCC demonstrated superior efficacy in melasma treatment and recurrence prevention compared to TCC monotherapy.