Botulinum toxin type A may have a role in improving the appearance and quality of new scars in patients at risk of abnormal scarring, according to a new systematic review and meta-analysis published in the July 2026 issue of Plastic and Reconstructive Surgery.
The study reviewed 19 studies involving 686 patients and found botulinum toxin type A was associated with improved scar quality, reduced scar width and higher patient satisfaction across several commonly used scar assessment scales.
Lead author Dr Carlos Zavaleta-Corvera, of Universidad Científica del Sur in Lima, Peru, said the treatment appears to be ‘a promising tool for scar prevention and scar quality improvement’.
The findings add to growing interest in earlier scar modulation strategies, particularly for patients prone to hypertrophic scarring, keloid formation or poor aesthetic scar outcomes following surgery or trauma.
Pathological scarring and the clinical burden of poor wound healing
Pathological scars, including hypertrophic scars and keloids, remain a common and often difficult clinical problem. While scar appearance is a major concern for many patients, the issue is not purely cosmetic. Thickened or raised scars may also cause pain, pruritus, restricted movement and psychological distress, particularly when they occur in visible areas or across mobile anatomical regions.
The authors noted that approximately 100 million people develop new scars each year, including around 11 million hypertrophic or keloid scars. They also reported that pathological scars affect between 4.5 and 16 percent of people with a genetic predisposition, with incidence rates ranging from 39 to 68 percent in surgical patients and 32 to 94 percent following traumatic injuries.
Scar formation is influenced by a complex wound healing process involving haemostasis, inflammation, proliferation, re-epithelialisation and tissue remodelling. When this process becomes dysregulated, excessive fibroblast activity, abnormal collagen deposition and increased wound contraction can contribute to hypertrophic or keloid scar formation.
Significant improvements across scar assessment scales
The review included randomised controlled trials and cohort studies identified through PubMed, Scopus, Embase and Web of Science. Seventeen of the included studies were randomised controlled trials and two were cohort studies.
Outcomes included scar quality, patient satisfaction and adverse effects. Scar assessment was performed using several validated tools, including the Vancouver Scar Scale, visual analog scale, Stony Brook Scar Evaluation Scale, Patient and Observer Scar Assessment Scale and Patient Scar Assessment Scale.
Across the studies reviewed, botulinum toxin type A was associated with significant improvements on several measures. Vancouver Scar Scale scores favoured botulinum toxin type A, suggesting reduced scar severity, while visual analog scale results indicated improved aesthetic perception. Scar width was also reduced in the botulinum toxin type A groups.
Results on the Stony Brook Scar Evaluation Scale and Patient and Observer Scar Assessment Scale also favoured treatment. The Patient Scar Assessment Scale, which reflects the patient’s own experience of symptoms such as pain, itching, stiffness and cosmetic impact, did not show a statistically significant difference between groups.
Patient satisfaction was higher among those treated with botulinum toxin type A, with the meta-analysis reporting a relative risk of 1.83 compared with controls. Adverse effects were described as minimal and transient, with no serious adverse effects reported in the studies reviewed.
Reducing mechanical tension during early wound repair
By relaxing nearby muscles, the authors note that botulinum toxin type A may reduce tension across a healing wound, creating a more favourable environment for early scar formation.
This is clinically relevant because increased tension along wound margins is a recognised contributor to widened scars and abnormal scar development. By limiting repetitive movement and reducing traction on wound edges during early healing, botulinum toxin type A may help support a narrower and more controlled scar response.
Dr Zavaleta-Corvera said its potential value may be particularly relevant in areas exposed to frequent movement, including the face, neck, chest, abdomen and periocular region.
Fibroblast activity, collagen remodelling and inflammatory modulation
According to the authors, botulinum toxin type A may exert antifibrotic effects by modulating fibroblast activity and downregulating transforming growth factor-beta, which is involved in fibroblast differentiation and myofibroblast activity. It may also influence extracellular matrix homeostasis by regulating collagen biosynthesis and matrix metalloproteinase-mediated degradation.
The authors noted that these effects may support a more organised collagen remodelling process. Botulinum toxin type A may also attenuate neurogenic inflammation by inhibiting the release of pro-inflammatory neuropeptides, including substance P, transforming growth factor-beta and calcitonin gene-related peptide.
Together, these mechanical and biological effects may help explain why botulinum toxin type A was associated with improved scar quality in the studies reviewed.
Clinical relevance in high-movement and high-tension anatomical sites
For plastic surgeons and other medical practitioners involved in wound closure and scar management, the findings suggest a possible adjunctive role for botulinum toxin type A in selected patients at higher risk of abnormal scarring.
The review noted positive findings in a range of surgical and traumatic contexts, including thyroidectomy, mammaplasty, abdominoplasty, epicanthoplasty, cleft lip repair and traumatic facial wounds. Benefits appeared most relevant where wound tension, movement or aesthetic visibility were important considerations.
In practical terms, the findings point to the possibility of intervening earlier in the scar formation process, rather than relying only on established scar treatments after abnormal scarring has developed.
However, the authors emphasised that botulinum toxin type A should not be viewed as a replacement for existing scar management strategies. Rather, it may have a role as part of a broader approach that can include surgical technique, silicone therapy, corticosteroid injections, pressure therapy, laser treatment and other established interventions where appropriate.
The authors concluded that botulinum toxin type A appears to be an effective and safe intervention for improving the quality of surgical and traumatic scars, helping to prevent pathological scarring by reducing muscle tension and modulating fibroblast and inflammatory activity. While the findings are promising, they cautioned that the current evidence is not yet sufficient to support a standardised clinical protocol.
