Botulinum Toxin Type A Effective for Treatment of Hypertrophic Scars

hypertrophic scar
Close up of cyanotic keloid scar caused by surgery and suturing, skin imperfections or defects. Hypertrophic Scar on skin, dermatology and cosmetology concept.
Significant clinical and cosmetic improvement was seen after treatment with botulinum toxin type A.

Botulinum toxin type A can lead to significant clinical and cosmetic improvement in patients with hypertrophic scars, according to study research published in the Journal of Cosmetic Dermatology.

Researchers conducted a split‐scar, double‐blind, randomized and controlled trial of botulinum toxin type A injection in 30 adult patients with old hypertrophic scars. The entire scar was treated, with each side randomly assigned to receive 1 of 2 treatments: botulinum toxin type A or 0.9% normal saline once monthly for 3 consecutive months.

Patients were recruited from an urban, university‐based outpatient clinic from January 2019 to June 2019. The Vancouver Scar Scale (VSS) and digital photograph standardization were used to assess the scars.

A total of 21 participants (mean age 24.86±6.98 years; 20 men) completed the study. The researchers found that the mean VSS score for the botulinum toxin type A‐treated half of the scars decreased from 7.29±2.327 before the injection to 5.33±2.41 after the injection, which was highly significant (P =.01). In the control group, the mean VSS decreased insignificantly from 7.29±2.327 before the injection to 7.10±2.234 after the injection (P =.104).

At 6 months’ follow-up, patients were generally satisfied with the botulinum toxin type A-treated side (95% CI, 1.22-2.30; P =.016), with the majority of patients (66.7%) reporting that they were “slightly satisfied” with the results.

Study limitations include the smaller population and the shorter length of some scars, which could have not guaranteed diffusion prevention.

“The present split-scar, double-blind, randomized and controlled study demonstrated that treating older hypertrophic scars (range 1-15 years) could result in their reduction and improvement of their surgical outcome,” stated the investigators.

“Further studies on different scar types and at various time points (fresh vs. mature scars) should give more insights on better approaches using [botulinum toxin type A] for treating scars,” they concluded.


Elshahed AR, Elmanzalawy KS, Shehata H, ElSaie ML. Effect of botulinum toxin type A for treating hypertrophic scars: A split‐scar, double‐blind randomized controlled trial [published online July 15, 2020]. J Cosmet Dermatol. doi: 10.1111/jocd.13627