Botulinum Toxin Dosing for Anhidrosis (Hyperhidrosis Treatment)
For the treatment of anhidrosis (hyperhidrosis), the recommended dose of Botox (botulinum toxin type A) is 50 units per axilla, which has been shown to effectively eliminate axillary sweating for 6-8 months. 1
Dosing Guidelines by Anatomical Location
Axillary Hyperhidrosis
- Recommended dose: 50 units of Botox per axilla
- Efficacy: Complete anhidrosis achieved by day 3 post-injection
- Duration of effect: 6-8 months before wearing off
- Insufficient dosing: Lower doses (15-20 units) showed no appreciable effect 1
Palmar Hyperhidrosis
- Recommended dose options:
- 50 units per palm - effective with less hand weakness
- 100 units per palm - slightly more effective but with greater risk of weakness
- Administration: Intradermal injections at 20 sites in each palm
- Duration of effect: At least 2 months in all patients, up to 6 months in most patients 2
- Important side effect: Temporary decrease in finger pinch strength (23% decrease with 50U, 40% decrease with 100U) 2
Administration Technique
- Administer via intradermal injections
- For axillary treatment: Multiple injection sites throughout the axilla
- For palmar treatment: 20 injection sites distributed across each palm
Mechanism of Action
Botulinum toxin works by inhibiting acetylcholine release at the neuromuscular junction by cleaving the synaptic Vesicle Associated Membrane Protein (VAMP), which blocks cholinergic innervation to sweat glands, resulting in temporary anhidrosis 3
Safety Considerations
- Healthcare providers should have epinephrine and antihistamines available during administration
- Risk of anaphylaxis is <2% 3
- For palmar hyperhidrosis, patients should be warned about potential temporary weakness in hand muscles:
- Handgrip strength typically unaffected
- Finger pinch strength may decrease for several months 2
Storage Requirements
- Refrigerate at 2°C to 8°C (36°F-46°F)
- Keep in original carton to protect from light
- Do not freeze or shake 3
Treatment Duration and Follow-up
- Effects typically last 6-8 months for axillary hyperhidrosis 1
- Effects last at least 2 months, and up to 6 months for palmar hyperhidrosis 2
- Repeated treatments maintain efficacy similar to first treatments 4
Clinical Pearls
- Higher doses (50U) are necessary for effective treatment of axillary hyperhidrosis; lower doses (15-20U) showed no effect
- For palmar hyperhidrosis, consider the trade-off between efficacy and hand weakness when selecting between 50U and 100U doses
- Treatment can be repeated after relapse with similar efficacy to initial treatment
- The anhidrotic effect typically begins within 2-3 days after injection