Influence of the cosmetic use of botulinum toxin type a on temperature measurements using infrared thermography

This study aims to assess the influence of the cosmetic use of Botulinum toxin type A (BTX-A) on temperature measurements using Infrared thermography (IT). A quantitative cross-sectional study was conducted with 16 patients to examine the cosmetic application of BTX-A in the upper third of the face to treat dynamic wrinkles (expression lines). The substance used in the patients was Botulinum Toxin type A DYSPORT^® 500 IU. A thermogram in frontal norm was acquired from each patient in three different moments: (M1) before BTX-A application, (M2) 10 min after BTX-A application, and (M3) five days after BTX-A application. The ROIs were demarcated in each image with a diameter of 10 mm, and then the average temperature values of each ROI were recorded. Mixed ANOVA, with Tukey's post hoc test, was used to determine interactions between factors in the dependent variable. The paired T-test was used to assess whether the mean temperatures on the face's right and left sides were statistically different. The significance level was set at 5%, considering p < 0.05. For the left-side temporal ROI, statistically significant differences were observed only between the different assessed times (p = 0.010). Considering the mean temperature difference, at the temporal ROI, a reduction of the M2 temperature was observed (ΔT = 0.3 ℃) and an increase at M3 (ΔT = 0.6 ℃). The cosmetic use of BTX-A may alter skin temperature values assessed using IT, and this effect can last for days.