Information on masseter botulinum toxin
The masseter is a strong chewing muscle that works when the jaw closes. Persistent clenching or grinding (bruxism) can make this muscle more prominent in some people and cause jaw fatigue, pain and a wider-looking lower face. Masseter treatment means injecting botulinum toxin type A into this muscle to temporarily reduce its excessive contraction force.
Purpose and expectations
The aim is not to eliminate chewing but to reduce excessive muscle force. Systematic reviews have reported reductions in bite force and in some bruxism-related complaints in suitable people. Changes in muscle volume develop more slowly. However, studies used different doses and methods; the certainty of evidence is limited and the effect is not permanent.
Assessing the cause first
Clenching may be related to stress, sleep disorders, certain medicines and dental-jaw structure. If there is marked tooth wear, jaw-joint pain or limited mouth opening, a dental assessment is important. Botulinum toxin does not replace a night guard, a sleep assessment or psychological support; when needed it is planned alongside them.
Treatment details
Duration: About 15–20 minutes.
Who it is for: Adults with teeth clenching or prominent masseter muscles who have also had a dental assessment.
Number of sessions: A single session; the need for repetition is usually assessed months later according to symptoms. The final plan is set by the physician after the examination.
Possible risks
Pain and bruising at the injection site and temporary chewing fatigue may occur. Less commonly, smile asymmetry, a sunken look in the cheek area or headache may develop. Generalized muscle weakness or difficulty swallowing or breathing requires urgent medical assessment.
Who may not be suitable?
Infection in the area, a history of neuromuscular disease, pregnancy and breastfeeding, allergy to a product component and interacting medicines are assessed separately.
Aftercare
Not massaging the area in the first hours and briefly avoiding intense exercise may be advised. Hard foods may feel tiring in the first days.
Frequently asked questions
When does it start to work?
Reduced muscle force is usually noticed within the first weeks; changes in the jawline develop more slowly, over weeks to months.
How long does it last?
The effect is not permanent and its duration varies. Repeat treatment is decided by symptoms and examination, not by a calendar.
Does it stop clenching completely?
No. It can reduce muscle force but does not remove the cause of clenching.
This text is intended for general information and is not personalized diagnostic or treatment advice. Eligibility is determined after a medical history and examination. Outcomes may vary from person to person; a specific result cannot be guaranteed.
References
- Fedorowicz Z, et al. Botulinum toxin for masseter hypertrophy. Cochrane Database Syst Rev. 2013. PMID: 24018587.
- Rauso R, et al. Botulinum toxin type A injections for masticatory muscles hypertrophy: A systematic review. J Craniomaxillofac Surg. 2022. PMID: 34620536.
- Chen Y, et al. Effectiveness of Botulinum Toxin Injection on Bruxism: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Aesthetic Plast Surg. 2023. PMID: 36694050.
