What is the recommended dose and injection site of Botox (Botulinum toxin) for treating blepharospasm?

Botox Dosing and Injection Sites for Blepharospasm

Recommended Treatment Approach

For blepharospasm, start with 2.5-5.0 units of botulinum toxin per injection site in the pretarsal portion of the orbicularis oculi muscle of the upper eyelid, with additional injections in the lower eyelid, for a typical total dose of 25-50 units per eye (50-100 units bilaterally). 1

Formulation Selection

• OnaBoNT-A (Botox) and incoBoNT-A (Xeomin) are equally effective and should be considered as first-line treatment options for blepharospasm. 2
• AboBoNT-A (Dysport) is a possibly effective treatment option but has less robust evidence. 2
• All three formulations demonstrate stable efficacy over long-term treatment (mean 11.2 years) with no significant differences in clinical outcomes. 3

Specific Dosing by Formulation

Botox (OnaBoNT-A)

• Mean effective dose: 47 ± 10 units per treatment session 3
• Initial dosing: 2.5-5.0 units per injection site 1
• Historical standard: 12.5 units per side (25 units total) 4

Xeomin (IncoBoNT-A)

• Mean effective dose: 62 ± 11 units per treatment session 3
• Starting dose: 2.5-5.0 units per injection site 1
• Use a 1:1 conversion ratio when switching from Botox to Xeomin 1

Dysport (AboBoNT-A)

• Mean effective dose: 120 ± 35 units per treatment session 3

Optimal Injection Technique

The pretarsal injection technique is superior to traditional triple injection methods and should be the preferred approach. 5

Pretarsal Technique (Preferred)

• Two injections into the pretarsal portion of the orbicularis oculi muscle of the upper eyelid 5
• Additional injection(s) into the lower eyelid as needed 5
• This technique achieves 95% treatment success rate versus 81% with triple injection 5
• Duration of benefit: 12.5 weeks versus 8.5 weeks with triple injection 5
• Significantly lower ptosis rate compared to traditional techniques 5

Traditional Triple Injection (Alternative)

• Two injections into the upper eyelid 5
• One injection into the lower eyelid 5
• May also include injections into the eyebrow region for eyebrow spasm 6

Treatment Timeline and Expectations

• Onset of therapeutic effect: 6.1 ± 3.3 days after injection 3
• Duration of effect: 10.2 ± 3.5 weeks 3
• Recommended re-injection interval: 3-6 months (typically every 12 weeks) 3, 1
• Note: Therapeutic effects begin to wane approximately 2 weeks before the standard re-injection interval, so shorter intervals may improve outcomes 3

Dose Stability and Adjustments

• 85% of patients maintain stable doses throughout long-term treatment 3
• 90% of patients maintain stable clinical improvement over time 3
• Global Clinical Improvement score: 2.5 ± 0.6 (on 0-3 scale, where 3 = marked improvement) 3

Safety Profile and Adverse Effects

• Overall adverse effect frequency: 3.0% 3
  • Ptosis: 2.3% 3
  • Dry eye: 0.5% 3
  • Diplopia: 0.2% 3
• All adverse effects are mild and transient 3, 4, 6
• No systemic side effects reported in large case series 6
• The pretarsal technique significantly reduces ptosis risk compared to traditional injection methods 5

Critical Pitfalls to Avoid

• Avoid excessive dosing initially: Start with lower doses (2.5-5.0 units per site) to minimize risk of drug diffusion to adjacent muscles, particularly given FDA boxed warnings about diffusion-related adverse events 1
• Do not use excessively long re-injection intervals: The standard 12-16 week interval may be too long, as therapeutic effects wane around 10 weeks; consider 10-12 week intervals for optimal symptom control 3
• Avoid non-pretarsal injection techniques when possible: The pretarsal approach provides superior efficacy and safety compared to traditional methods 5
• Do not confuse blepharospasm with other conditions: Patients with combined blepharospasm and involuntary levator palpebrae inhibition respond particularly well to pretarsal injections 5