Title : Botulinum toxin a for scar modulation: Systematic review of outcomes and clinical modifiers
Abstract:
Background: Hypertrophic and unesthe4c scarring remains a major concern in aesthe4c and dermatologic prac4ce. Conven4onal measures such as silicone or cor4costeroids show inconsistent
benefit and lack standardized protocols. Botulinum toxin A (BoNT-A) has emerged as an adjunct through muscle relaxa4on and fibroblast modula4on. This review evaluates its efficacy, safety, and pa4ent-reported outcomes in surgical and trauma4c scars, with specific focus on 4ming, dose, and anatomical site as key clinical modifiers.
Methods: This review followed PRISMA 2020 and was registered in PROSPERO. MEDLINE, Embase, Cochrane, and ClinicalTrials.gov were searched through September 2025. Eligible studies included RCTs or prospec4ve compara4ve trials evalua4ng peri- or early postopera4ve BoNT- A in adults. Primary outcomes were scar quality using validated scales. Secondary outcomes included pa4ent sa4sfac4on, pruritus, pain, and adverse events. Timing, dose, and anatomical site were assessed as effect modifiers within dermatologic dosing ranges.
Results: Sixteen studies with 456 pa4ents were included. BoNT-A consistently improved scar quality at 3-6 months and enhanced overall skin characteris4cs. Observer-rated scales showed improvements in pigmenta4on, pliability, vascularity, and texture, with reduced hypertrophy. Pa4ents reported greater sa4sfac4on, less pain and pruritus, and visible decreases in redness. Scar scales showed benefit in 6/7 VSS and 4/5 mSBSES trials, with 5/7 repor4ng narrower scars. Improvements were most pronounced in cosme4cally sensi4ve regions (face, neck, hands) and in keloid-prone areas (chest, shoulders, jawline). Early administra4on and higher dosing in high-tension sites yielded superior results. Reported adverse events were mild, transient, and limited to local erythema or ecchymosis, with no serious complica4ons.
Conclusion: BoNT-A improves scar cosmesis and pa4ent outcomes with a favorable safety profile. Timing, dose, and anatomical site are modifiable factors that op4mize efficacy, posi4oning BoNT-A as a prac4cal, evidence-based adjunct in both aesthe4c and dermatologic prac4ce. Standardized protocols are essen4al for broader clinical adop4on.
