Masseter.
The large chewing muscle at the jaw angle. Botulinum toxin there eases teeth grinding (bruxism) and can make a wide lower face look slimmer.
The masseter in the lexicon: function, enlargement through bruxism, treatment with botulinum toxin, effect on jaw pain and facial shape, dose and durability.
A closer look.
The masseter muscle runs from the cheekbone to the angle of the lower jaw and is – relative to its weight – the strongest muscle in the body. It closes the jaw when chewing. Anyone who grinds at night or clenches during the day trains it constantly: it thickens, the jaw angle widens, often accompanied by headaches and jaw pain.
Botulinum toxin is placed at several points in the muscle belly and reduces its strength for a few months. Symptoms usually ease within two weeks; the visible slimming of the lower face develops over four to eight weeks because the muscle shrinks slowly. The dose is clearly higher than for expression lines.
Common side effects are a temporary feeling of weakness when chewing hard foods and slight asymmetries when smiling if neighbouring muscles are affected. The effect lasts four to six months; a night guard remains sensible to protect the teeth.
This lexicon entry is general information and does not replace the medical consultation required under German law (§ 630e BGB).
At a glance.
A question about Masseter? Send us a short WhatsApp message – we usually reply the same working day.
Ask via WhatsAppFrequently asked questions.
Can I still chew normally afterwards?
Yes. Only the maximum force is reduced; very chewy foods can be more tiring in the first weeks.
Does the face stay slimmer permanently?
The muscle shrinks as long as it is treated; without treatment it returns to its old size over months.
Sources and further reading.
- NHS: Botox injections – patient information
- DGBT – German Society for Aesthetic Botulinum Toxin Therapy
- BfArM – Federal Institute for Drugs and Medical Devices
- European Medicines Agency (EMA)
- NHS: teeth grinding (bruxism)
- § 630e BGB – duty to inform before treatment (German Civil Code)
- AWMF – German clinical practice guidelines
External links open in a new window; their operators are responsible for their content. Medical responsibility for this page: Katayoun Mostaghimi, specialist in general medicine. Last updated: 2026-10-05.
Talk to the physician.
Book on DoctolibOr simply call: +49 1520 8367711 · info@vivaderm.de
Or start with a consultation only: consultation appointment (€50, credited against a treatment)