Quick answer:
Botulinum toxin injected into the skin of the underarms temporarily blocks the nerve signals that activate sweat glands. It can dramatically reduce excessive underarm sweating within one to two weeks, and results often last six months or longer. Botulinum toxin is FDA-approved for severe primary axillary hyperhidrosis that is not managed adequately with topical agents.
What is hyperhidrosis?
Primary hyperhidrosis is sweating beyond what the body needs for temperature control, often starting in adolescence and affecting the underarms, palms, soles or face. It can interfere with work, clothing choices and confidence.
How does the treatment work?
Sweat glands are activated by acetylcholine released from nerve endings. Botulinum toxin blocks this release locally, so the treated glands produce much less sweat. Other sweat glands elsewhere continue to work normally.
What happens during the procedure?
- Mapping
– a starch-iodine test may be used to show the most active sweating area.
- Numbing
– topical numbing or ice can be used.
- Injections
– many small, shallow injections are placed across each underarm.
- Finish
– the procedure takes around 15–30 minutes.
Results and duration
- Sweating reduces noticeably within a few days to two weeks.
- Results commonly last six to nine months, sometimes longer.
- Repeat treatment restores the effect when sweating returns.
Side effects
Mild soreness, bruising or tenderness at injection points are common and short-lived. Some people notice increased sweating in other areas, but this is usually mild. Serious side effects are uncommon when performed correctly.
Alternatives
- Clinical-strength antiperspirants (aluminium chloride)
- Prescription topical anticholinergics
- Microwave-based sweat gland reduction devices
- Oral medications, considered on a case-by-case basis
Is my sweating "excessive"?
- Sweat soaks through clothing on most days, regardless of temperature
- You change shirts or carry spares regularly
- Sweating limits clothing colours or social activities
- Antiperspirants have not helped enough
Sweating that starts suddenly in adulthood, occurs at night, or affects the whole body should be checked for other medical causes.
Preparing for treatment
- Shave a day or two before if advised.
- Avoid antiperspirant on the day so the mapping test is accurate.
- Wear dark, loose clothing.
After treatment
Avoid heavy exercise and saunas for 24 hours. Mild tenderness fades within a day or two. You can usually return to work immediately. Keep a simple note of when sweating returns, which helps plan the next session.
Cost-effectiveness over a year
Because results usually last six months or longer, many people need one or two sessions a year. Booking before summer or a major event is a common strategy.
Frequently asked questions
Is it safe to stop sweating in the underarms?
Yes. The underarms account for a small fraction of total body sweating, so temperature control is not meaningfully affected.
Can palms be treated too?
Yes, though palm injections are more uncomfortable and may temporarily weaken grip.
When should I book before summer?
Two to four weeks ahead allows the full effect to develop.
References
- U.S. FDA – Botulinum toxin labelling for severe primary axillary hyperhidrosis
- International Hyperhidrosis Society – Treatment guidelines
This article is general information, not medical advice or a diagnosis. Suitability, recovery and results vary from person to person. Please consult a qualified doctor before any procedure.
