Acne vulgaris as an inflammatory disease, with an excessive production of subdermal fat, modifies the dynamics of the bloodstream, and consequently temperature, on the affected skin zone. A high percentage of this heat interchange is manifested as electromagnetic radiation with far-infrared wavelengths, which can be captured through a thermal imaging camera. A technique based on thermal image analysis for efficiency assessment in acne vulgaris is described. The procedure is based on computing statistical parameters of thermal images captured from the affected skin zone being attended by an acne treatment. The proposed technique was used to determine the skin thermal behavior according to acne severity levels in different acne treatment stages. Infrared images of acne skin zones on eight patients, diagnosed with acne vulgaris and attended by one specific acne treatment, were weekly registered during 11 weeks. The infrared images were captured until no more improvement in affected zones was detected. The obtained results suggest a direct relationship between the used statistical parameters, particularly first- and second-order statistics, and the acne vulgaris severity level on the affected zones.