What is the recommended onabotulinumtoxinA (Botox) dose and injection protocol for an adult with primary palmar and axillary hyperhidrosis who has no contraindications (e.g., neuromuscular disease, pregnancy, active infection at the injection site, or hypersensitivity to botulinum toxin)?

Botox for Primary Palmar and Axillary Hyperhidrosis

For axillary hyperhidrosis, inject 50 U of onabotulinumtoxinA (Botox) per axilla (100 U total) distributed across 10-15 injection sites per side; for palmar hyperhidrosis, inject 50-100 U per palm (100-200 U total) distributed across 20 sites per palm, with nerve block anesthesia strongly recommended for palmar injections to reduce pain and improve tolerability.

Axillary Hyperhidrosis Protocol

Dosing and Technique

• Total dose: 50 U per axilla (100 U total for both axillae) is the standard effective dose, though some protocols use up to 100 U per axilla 1, 2
• Distribute injections across 10-15 evenly spaced intradermal injection sites per axilla, approximately 1-2 cm apart 1, 2
• Inject intradermally at a depth of 2-3 mm into the dermis where sweat glands are located 2

Expected Outcomes

• Median sweat reduction of 71% at 4 weeks post-injection compared to baseline 1
• Duration of effect: median 34 weeks (approximately 8 months) before repeat treatment needed 1
• Patients report marked improvement in daily activities and quality of life 1

Safety Profile

• Axillary injections are well-tolerated with minimal side effects 1, 2
• No serious adverse events reported in long-term studies 1, 2
• Local pain during injection is the primary complaint 2

Palmar Hyperhidrosis Protocol

Critical Anesthesia Requirement

• Regional nerve block anesthesia is strongly recommended (median and ulnar nerve blocks at the wrist) before botulinum toxin injection of the palm 3
• Nerve block is superior to skin cooling for patient comfort during palmar injections 3
• Without adequate anesthesia, palmar injections are extremely painful and poorly tolerated 2

Dosing and Technique

• Standard dose: 50-100 U per palm (100-200 U total for both hands) 4, 5
• The 50 U dose is effective and causes less hand weakness than 100 U 4
• Distribute across 20 evenly spaced intradermal injection sites per palm 4
• Inject 2.5-5 U per site depending on total dose chosen 4, 5

Expected Outcomes

• Median sweat reduction of 42% at 4 weeks with significant subjective improvement 1
• Duration of effect: median 25 weeks (approximately 6 months) before repeat treatment needed 1
• At 6 months, two-thirds of patients still show anhidrotic effect 4

Critical Safety Considerations and Hand Weakness

• Transient weakness of intrinsic hand muscles occurs in approximately 40% of patients (9 of 21 patients in one study) 1
• With 50 U per palm: finger pinch strength decreases 23% at 2 weeks, gradually improves but remains 7% below baseline at 6 months 4
• With 100 U per palm: finger pinch strength decreases 40% at 2 weeks, remains 11% below baseline at 6 months 4
• Handgrip strength is not significantly affected at either dose 4
• The weakness is not disabling but patients must be counseled about temporary reduction in fine motor function 1

Severity-Based Adjustments

Severe Palmar Hyperhidrosis (≥1 mg/cm²/min)

• Severe cases require higher doses and more injection sites to achieve satisfactory results 5
• Consider starting with 100 U per palm in severe cases 5
• Even with treatment, severe cases maintain higher residual sweat production than mild cases 5

Mild Palmar Hyperhidrosis (<1 mg/cm²/min)

• 50 U per palm is typically sufficient for mild cases 5
• These patients achieve better relative reduction in sweating 5

Repeat Treatment Protocol

• Repeat injections are as effective as initial treatment with no evidence of tachyphylaxis 1
• Schedule repeat treatment when symptoms return to bothersome levels, typically 6-8 months for axillae, 5-6 months for palms 1
• Use the same dose and technique that was effective previously 1

Common Pitfalls to Avoid

• Do not inject palmar hyperhidrosis without adequate anesthesia—this causes severe pain and poor patient tolerance 3, 2
• Do not fail to counsel patients about hand weakness before palmar injections—this is expected and temporary but can affect occupational activities requiring fine motor control 1, 4
• Do not use subcutaneous injection—intradermal placement is essential for targeting eccrine sweat glands 2
• Do not underdose severe cases—they require higher doses and more injection sites than mild cases 5
• Do not confuse this therapeutic use with botulism treatment—the evidence provided about botulism antitoxin is irrelevant to hyperhidrosis treatment 3, 6, 7