Maximum Botox Dose for Trapezius Muscle
For therapeutic applications in the trapezius muscle, doses typically range from 20-100 units per injection site, with total doses commonly exceeding the FDA-approved 400 unit maximum when treating multiple body regions, which has been demonstrated as safe and effective in clinical practice. 1
Dose Range Based on Clinical Evidence
Standard Therapeutic Dosing
- Single injection site: 20 units of onabotulinumtoxinA has been studied for myofascial trigger points in the upper trapezius, though this showed limited efficacy compared to saline 2
- Cosmetic/aesthetic applications: Studies on bilateral trapezius hypertrophy for shoulder contouring have used BTxA injections successfully, though specific doses are not explicitly stated in the available evidence 3
High-Dose Safety Profile
- Doses exceeding 400 units per session have been documented as safe when treating multiple body regions, including dystonia and spasticity cases 1
- In a study of 68 patients receiving >400 units per session, over 70% reported "very much improved" or "much improved" outcomes with no serious adverse effects 1
- Mean duration of benefit was 9 weeks with high-dose protocols 1
Practical Dosing Considerations
Injection Technique for Trapezius
- Superior trapezius: Target the horizontal 1/5-2/5 and vertical 2/10-4/10 sections for optimal intramuscular nerve distribution 4
- Middle trapezius: Target the horizontal 1/5-3/5 and vertical 4/10-5/10 sections 4
- Avoid the horizontal 2/5-3/5 and vertical 2/10-4/10 nerve entry points to prevent nerve trunk damage causing paralysis 4
Reconstitution and Storage
- Reconstitute with preservative-free 0.9% sodium chloride only 5
- Must be refrigerated and discarded if more than 4 hours elapse after reconstitution due to lack of preservatives 5
- For 100 units: add 2.5 mL for a concentration of 4 units per 0.1 mL, or 2.0 mL for 5 units per 0.1 mL 6
Clinical Algorithm for Dosing
Initial treatment approach:
- Start with 20-50 units per trapezius muscle for first-time patients 2, 5
- Assess response at 3-6 weeks 2
- Subsequent doses should be individualized based on response, with larger doses often required when initial response is insufficient 5
For bilateral treatment:
- Total doses of 40-200 units (20-100 units per side) are reasonable based on the safety profile of high-dose protocols 1, 3
Safety Considerations
Common Pitfalls
- Do not exceed 4 hours between reconstitution and injection to maintain sterility 5
- Avoid injecting near nerve entry points to prevent unwanted paralysis 4
- Monitor for mild adverse effects that typically resolve within one week 2