Complications of facial cosmetic botulinum toxin A injection: analysis of the UK Medicines & Healthcare Products Regulatory Agency registry and literature review.

[BACKGROUND] Botulinum toxin A (BoNT-A) injection is one of the most frequently undertaken procedures in aesthetic medicine. The Medicines & Healthcare products Regulatory Agency (MHRA) is the government body in the United Kingdom (UK) mandated to ensure that the provision and administration of medicines is safe. We analyzed adverse events of facial cosmetic BoNT-A injections reported to the MHRA and assessed whether the incidence of reported adverse events in this government registry is comparable to published retrospective and prospective studies.

[METHODS] A freedom of information (FOI) request was submitted to the MHRA to obtain recorded complications of BoNT- A. Complications reported to the MHRA between 1991 and 2020 were analyzed. Only cases with BoNT-A where the indication was specified as for facial cosmetics were included in the analysis. Additionally, the literature was reviewed on adverse events of facial cosmetic BoNT- A injections, and a statistical meta-analysis of complication rates was carried out.

[RESULTS] A total of 188 adverse events of aesthetic BoNT-A injections were reported to the MHRA. The literature search resulted in 30 studies and a total of 17,352 injection sessions, where the complication rate was 16% (95% CI = 8% to 25%). Frequent adverse events included localized skin reactions such as bruising with an incidence of 5% (95% CI = 3% to 7%), headache in 3% (95% CI = from 1% to 5% ), and facial paresis in 2% (95% CI = 1% to 3%) of injection sessions.

[CONCLUSIONS] This is the first paper to obtain and evaluate data on adverse events of BoNT-A from the MHRA. An estimate of the likely complication rate of aesthetic BoNT-A in the UK, according to the MHRA database, is significantly lower than the rate recorded from our meta-analysis of the international literature. This suggests that the MHRA may be underestimating the adverse events of aesthetic BoNT-A treatment, which would have implications for patient safety and informed consent. Therefore, legislative changes may be required to ensure more robust reporting of aesthetic BoNT-A in the UK.