Literature review of the adverse events associated with botulinum toxin injection for the masseter muscle hypertrophy.

Botulinum toxin masseter injections are commonly performed procedures with good results and safety profiles. The majority of complications appeared within 2-4 weeks of injection and disappeared within 12 weeks. Despite the temporary nature of these complications, they often decrease patient satisfaction and confidence, so physicians should familiarize themselves with the regional anatomy and injection safety zones.