Botulinum toxin for excessive sweating (hyperhidrosis)
For hyperhidrosis, botulinum toxin is delivered to the nerve endings that stimulate the sweat glands, temporarily reducing excessive sweating; the dose is around 50 units per underarm and around 100 units per palm.
- Procedure time
- Underarms 15–20 minutes · palms 30 minutes
- Anaesthesia
- Usually not needed for underarms; topical anaesthetic and cooling for palms
- Recovery
- Back to normal the same day
- Sessions
- One session · assessed at week 4
- How long it lasts
- Underarms 6–9 months · palms 4–6 months
The target is a sweat gland, not a muscle
This treatment works differently from facial botulinum toxin. The target is not a muscle of expression but the nerve endings that stimulate the sweat glands.
The nerve ending releases acetylcholine, which switches the gland on. Botulinum toxin temporarily stops that release; without the signal, sweat production falls markedly.
The effect is confined to the area treated. The rest of the body’s sweating balance is not disturbed, and treating the underarms is not designed to create compensatory sweating somewhere else.
How the dose is calculated
For sweating, the dose is set by the surface area involved. Around 50 units per underarm and around 100 units per palm are typical.
The border of the sweating area can be made visible before treatment with a starch-iodine test. That way the units are distributed across the skin that actually sweats, and no injection is given outside the border.
- Surface area of the sweating region — the larger the area, the higher the total dose
- The site — palms need a wider, denser distribution of points than underarms
- Spacing between injection points — usually a grid of 1–2 centimetres
- How long the previous treatment lasted — if the effect faded early, the next dose is adjusted
The day of treatment
The area is cleaned and the injection points are marked. Injections are very superficial, with a short needle, at a large number of points: 10–20 per underarm, 30–40 per palm.
Underarm treatment needs no anaesthetic for most patients. Palms are more uncomfortable because the hand is more sensitive; topical anaesthetic and cooling are used there.
It takes 15–20 minutes for underarms and around 30 minutes for palms. You return to normal life the same day; avoid saunas, steam rooms and heavy exercise for the first 24 hours.
The timeline of the effect
The reduction in sweating usually begins within 2–7 days and becomes clear in week 2. Assessment is at week 4.
In the underarms the effect lasts 6–9 months on average, markedly longer than facial treatment. In the palms it is shorter, 4–6 months on average.
When it wears off, sweating returns gradually to its previous level. Treatment can be repeated; the interval is set by how quickly the symptom comes back.
What decides the result
The first thing is a correct diagnosis. Excessive sweating is sometimes a symptom of something else: thyroid disease, infection, hormonal change and some medicines can all increase it. Treatment is not planned until those possibilities have been excluded. If you have been investigated for this where you live, bring the results.
The second is distributing the units across the right area. If the border of the sweating region is drawn incorrectly, sweating continues at the edges and the result looks inadequate.
A known effect of palm treatment is a temporary reduction in hand grip strength; fine, gripping tasks can be harder for a few weeks. That possibility is discussed before treatment — and if your work depends on grip, it is worth timing the treatment around it.
Who this is not for, and what not to expect
Botulinum toxin is a prescription medicine with its own contraindications. The total units used in sweating treatment are higher than for the face, so your medication history and general health are assessed in more detail.
If the sweating is thought to be caused by another condition, that cause is investigated first. Treating without finding the underlying reason delays the diagnosis.
- Pregnancy and breastfeeding — not treated
- Neuromuscular disease (myasthenia gravis, Lambert-Eaton syndrome, motor neurone disease) — not treated
- Aminoglycoside antibiotics — they can amplify the effect of the toxin; not treated until the course is finished
- Active infection or inflammatory skin disease in the treatment area — not treated until it clears
- Known hypersensitivity to botulinum toxin — not treated
- Bleeding disorder or anticoagulant use — bruising is more likely; a doctor’s assessment is required
- The effect is not permanent; sweating returns gradually to its previous level when it wears off
This page is general information and does not replace a clinical examination. The method, dose and timescale that apply to you are decided by a doctor after examining you.
Frequently asked questions
How many units does sweating treatment use?
How long does it last?
Will I sweat more somewhere else?
What is palm treatment like?
What assessment happens first?
Pre-assessment
Describe your situation and we will answer with a measurement
Send a photograph or an X-ray. A doctor in the relevant speciality will reply with a graft range, a number of teeth or a dose range in units. If you are not suitable, we say so plainly.