Dysport for Masseter Reduction and Facial Slimming
Yes, Dysport (abobotulinumtoxinA) can be effectively used for masseter reduction to achieve facial slimming, particularly in young to middle-aged women seeking lower facial contouring. This is a well-established off-label aesthetic application with substantial clinical evidence supporting its efficacy and safety 1, 2.
Mechanism and Efficacy
Botulinum toxin type A chemically denervates the masseter muscle, reducing muscle bulk and creating a slimmer facial contour without surgery 1. The atrophic effect typically becomes visible 2-4 weeks after injection, with maximum effect achieved at approximately 3 months post-treatment 1, 3.
Expected Outcomes
- Muscle thickness reduction averages 31% at 3 months following initial injection 1
- Lower facial width reduction ranges from 3.94% at 2 weeks to 11.99% at 12 weeks, with sustained effect at 24 weeks 3
- Patient satisfaction is high, with 70% of patients reporting great satisfaction and an additional 23% generally satisfied 1
- Duration of effect typically lasts 6-12 months, requiring repeat sessions for maintenance 4
Injection Protocol
Dosing Considerations
The optimal dose varies widely in the literature, but typical protocols use 60-90 units of Dysport per side 1, 3. One large clinical series utilized Dysport specifically and demonstrated effectiveness with this dosing range 1. Note that Dysport has different potency compared to other botulinum toxin formulations, requiring dose conversion when comparing studies 2.
Injection Technique
Injections must be placed within the boundaries of the masseter muscle, respecting established safety zones 3, 4. The muscle can be palpated by having the patient clench their teeth, and injection points should be marked while the muscle is contracted 5.
Key anatomical considerations:
- Stay within the masseter muscle boundaries to avoid toxin diffusion to adjacent muscles 3
- Avoid the risorius muscle anteriorly to prevent smile asymmetry 3
- Consider combined injection into both masseter and platysma muscles for enhanced jawline definition 5
Adverse Effects and Management
Common Side Effects
Masticatory fatigue is the most common adverse effect, occurring as the muscle weakens 3. This is typically temporary and resolves as patients adapt.
Smile limitation and asymmetry can occur if toxin diffuses to the risorius muscle 3. Brazilian patients showed higher incidence of smile limitation (specific percentage not provided but noted as higher than Asian populations), possibly due to anatomical variations or injection technique 3.
Serious Complications
While the evidence provided focuses on masseter injections, general botulinum toxin complications include:
- Dysphagia (difficulty swallowing) if toxin diffuses to swallowing muscles 6
- Dry mouth from effects on salivary production 6
- Aspiration risk, particularly in patients with pre-existing neuromuscular disorders 6
Most side effects are temporary and resolve within 3-6 months as the toxin effect diminishes 6.
Patient Selection and Counseling
Ideal Candidates
This procedure is particularly effective for patients with masseter hypertrophy causing lower facial widening 1, 4. The technique has been extensively studied in Asian populations due to racial characteristics and dietary habits that promote masseter hypertrophy 1, 2, but has also demonstrated efficacy in Brazilian and other populations 3.
Patients who have undergone mandibular angle ostectomy but remain dissatisfied due to persistent masseter thickness are also good candidates 1.
Important Counseling Points
Informed consent must address:
- Temporary nature of results requiring repeat treatments every 6-12 months 4
- Potential for smile asymmetry or limitation 3
- Masticatory fatigue during the adaptation period 3
- Off-label use of the medication for this indication 2
- Expected timeline: visible results at 2-4 weeks, maximum effect at 3 months 1, 3
Despite side effects, 80% of patients in one study desired repeat treatment, indicating high overall satisfaction 3.
Clinical Considerations
Precise understanding of facial muscle anatomy is essential to decrease incidence of side effects 1. Reduction in masseter thickness can create relative prominence of the malar eminence and mandibular angle, which should be discussed with patients preoperatively 1.
The procedure offers significant advantages over surgical masseter resection:
- Simple technique with minimal invasiveness 1
- Few side effects when properly performed 1
- Rapid return to daily activities 1
- No long-term side effects reported in large case series 1
Multiple injection sessions are typically required to maintain long-term aesthetic results 4, and patients should be counseled about this ongoing commitment before initiating treatment.