Efficacy and safety of topical timolol 0.5% plus saline 0.9% versus each one alone in acne scar trichloroacetic acid‐CROSS therapy: A blinded randomized controlled trial

Trichloroacetic acid‐CROSS (TCA‐CROSS) or chemical reconstruction of scars is an approved method in the treatment of ICE‐PICK scars. Timolol is a blocker of beta‐adrenergic receptors that speeds up the healing of skin wounds. In this study, for the first time, the TCA‐CROSS technique was combined with the use of saline injection and topical timolol to increase the effectiveness of treatment, and reduce the number of treatment sessions and complications, and thus improve the aesthetic result. In this parallel‐group split‐face randomized controlled assessor and analyst‐blinded study, 45 patients with atrophic acne scars were randomly divided into 3 equal groups. TCA‐CROSS treatment was performed on all facial scars of patients. In group 1, before TCA‐CROSS, saline was injected under the scars on one side of the face, in group 2, after TCA‐CROSS, 0.5% timolol eye drops were applied on the scars on one side, and in group 3, saline was injected before TCA‐CROSS. After that, timolol eye drops were applied on the scars of the same side. In all groups, the choice of control side was random. The number of scars and patient and physician satisfaction were the main variables evaluating the effectiveness of the treatment. TCA‐CROSS improved scars in both control and treatment sides of all 3 groups. Although the number of scars decreased on the treatment side of groups 2 and 3, the decrease was not statistically significant. In the saline + TCA group, the number of scars on the treatment side was slightly more than on the control side. In the group of patients who used timolol, the severity and duration of scar hyperpigmentation were significantly lower (group 2 p = 0.016, group 3 p = 0.002). No permanent complication was observed in the patients. Patients' satisfaction in groups 2 and 3 was higher in the treatment side than the control side. The combination of saline injection followed by TCA‐CROSS is not recommended. Application of 0.5% timolol after TCA‐CROSS caused a slight decrease in scar severity and a significant reduction of post‐inflammatory hyperpigmentation (PIH) duration. So, the topical timolol makes a better result of TCA‐CROSS for acne scar treatment.