title: Adverse events associated with botulinum toxin injection: a multidepartment, retrospective study of 5310 treatments administered to 1819 patients.
abstract: BACKGROUND
  The injection of botulinum toxin is now commonly used for many therapeutic and cosmetic purposes but because of its increased use more adverse events are being reported.
  
  
  OBJECTIVE
  To retrospectively evaluate and analyze the safety of botulinum toxin injections in terms of purpose and the type of toxin administered.
  
  
  METHODS
  Data were collected on 1819 patients who underwent a total of 5310 treatments between 2005 and 2011 at a single tertiary medical center. Information on the dosage, treatment purpose, type of botulinum toxin, and any adverse events associated with these treatments were collected and analyzed. The generalized estimating equation (GEE) with the logistic link function was used to estimate the overall frequencies of adverse events. A multivariable GEE with the logistic link function was used to identify the factors associated with adverse events.
  
  
  RESULTS
  Among the 5310 botulinum toxin treatments in our study cohort, 2258 of which (42.5%) were used to treat hemifacial spasm, 184 adverse events (3.73%) were recorded, 114 (2.26%) muscle-related, and 71 (1.47%) muscle-unrelated. The highest number of adverse events (8.29%) was associated with the treatment of blepharospasm and the lowest (1.07%) with masseter hyperplasia. By multivariate analysis, the odds ratio for females was 1.577 (95% confidence interval [CI] = 1.052-2.364; p = 0.027) and for the dose was 1.006 (95% CI = 1.002-1.010; p = 0.005). When compared with upper face wrinkles, the odds ratio was 2.510 (95% CI = 1.400-4.499; p = 0.002) for blepharospasm, 0.375 (95% CI = 0.202-0.695; p = 0.002) for cervical dystonia, and 0.114 (95% CI: 0.015-0.862; p = 0.035) for masseter hyperplasia.
  
  
  CONCLUSIONS
  When injecting botulinum toxin for cosmetic purposes, practitioners should be cautious, especially when targeting the areas around the eyes, as these treatments are prone to cause adverse events.
authors.affiliation: Department of Dermatology, Asan Medical Center, University of Ulsan College of Medicine , Seoul , Korea.
authors.forename: Byung Wook
authors.initials: BW
authors.lastname: Kim
authors.forename: Gyeong-Hun
authors.initials: GH
authors.lastname: Park
authors.forename: Woo Jin
authors.initials: WJ
authors.lastname: Yun
authors.forename: Nark Kyoung
authors.initials: NK
authors.lastname: Rho
authors.forename: Kyoung Ae
authors.initials: KA
authors.lastname: Jang
authors.forename: Chong Hyun
authors.initials: CH
authors.lastname: Won
authors.forename: Sung Eun
authors.initials: SE
authors.lastname: Chang
authors.forename: Sun Ju
authors.initials: SJ
authors.lastname: Chung
authors.forename: Mi Woo
authors.initials: MW
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage / Q000009:adverse effects*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007267:Injections; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000008:administration & dosage / Q000009:adverse effects*; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A