In short: Botulinum toxin can clearly reduce excessive underarm sweating for several months, often around four to seven months. The first changes usually appear within the first week, although the effect does not develop equally fast in everyone. Completely dry underarms for a fixed period cannot be promised. When the sweating increases again, you and your doctor decide together whether and when another treatment makes sense.
How long does the effect last?
For planning purposes, a range of around four to seven months is a useful guide. Some people notice dampness again sooner, others benefit for longer. What is meant is a lasting reduction in sweat production. It does not mean that every treated person stops sweating under the arms entirely for that whole time.
In hyperhidrosis, the body produces more sweat than it needs to regulate its temperature. Botulinum toxin, often called „Botox“ in everyday language, temporarily blocks the signals that nerves send to the sweat glands. The glands are not removed in this treatment. As the block wears off, sweat production can increase again.
How long you will feel relief in daily life cannot be predicted exactly before the first treatment. The severity of the sweating and the treatment itself also play a part. A sensible goal is therefore less bothersome underarm wetness in everyday situations, for example at work or when meeting other people.
| Phase | What to expect | What matters for you |
|---|---|---|
| Before treatment | Assessment of the cause and of previous treatment | Note your symptoms, medication and what you have tried so far |
| First week | A reduction in sweating may become noticeable | Do not judge the result straight after the session |
| Up to about two weeks | The effect can continue to develop | Get in touch if there is no improvement |
| Following months | Often around four to seven months of less underarm wetness | Watch for the effect wearing off and how much it affects you |
Beforehand: cause and suitability
Heavy sweating deserves a medical assessment if it restricts you in daily life or does not improve enough with suitable antiperspirants. An antiperspirant reduces sweat production, while a deodorant mainly targets odour. An unsuccessful attempt with an ordinary deodorant therefore does not mean that all topical options have been exhausted.
In primary hyperhidrosis there is no identifiable underlying condition. Secondary hyperhidrosis, by contrast, can be linked to a thyroid disorder or to medication, for example. The cause should be assessed by a doctor in particular if the sweating is new, occurs at night or affects the whole body. Treating only the underarms would not resolve a possible underlying condition.
At Swiss Derma Clinic in Zurich we offer treatment for excessive underarm sweating. Before the first treatment, this includes an examination and a discussion of the advantages and disadvantages. Whether botulinum toxin is an option for you depends on the findings, your symptoms and the treatments you have already tried.
A little preparation helps with the dermatological assessment: Since when have you been sweating heavily? Are both underarms affected? Does it also happen while you sleep? Which products have you already tried, and how well did you tolerate them? Please also bring a list of your medication. Do not stop prescribed medicines on your own.
The session: small skin injections
The doctor first assesses the area where sweating is most pronounced. If needed, the area can be made visible with a starch-iodine test, in which sweating skin turns dark. Whether this test is required depends on the examination.
The active substance is then injected superficially into the underarm skin at several points using a fine needle. Unlike in the treatment of expression lines, the target here is the signal transmission to the sweat glands. The injections can feel uncomfortable or sting. On request, we pretreat the skin with a numbing cream.
Before your appointment, also ask whether and when you should shave your underarms and which products you may use on the day of treatment. The instructions can depend on the planned procedure. Tell the doctor about earlier treatments with botulinum toxin, including on other parts of the body, and about known allergies or unusual reactions to injections.
The first days and weeks
A final assessment is not yet possible straight after treatment. The reduction in sweating sets in with a delay. A change often becomes noticeable within the first week, and for some people only over the course of about two weeks. Dampness on the day of treatment therefore does not mean that the treatment is not working.
Try to observe comparable everyday situations: Do you still have to change your top? Are the sweat marks smaller? Does the underarm wetness still bother you just as much at work? Observations like these make the result easier to discuss than the expectation that the skin must be perfectly dry at all times.
You can usually return to your normal activities straight away. We recommend avoiding intensive exercise and sauna visits for a few days after treatment. We will discuss at your appointment when you can shave your underarms and use deodorant again.
If there is no effect
If you notice no improvement after about two weeks, or if individual areas continue to sweat heavily, contact the practice that treated you. The result will then be assessed by a doctor. This does not automatically mean that an additional injection is needed.
When the sweating increases again
After several months the underarm wetness can return. This is in line with the temporary effect of the treatment. What matters for further planning is how much the sweating bothers you again and how helpful the first treatment was for you.
A repeat treatment is not scheduled by the calendar alone. The doctor takes into account how things have gone so far, possible side effects and the requirements of the medicine used. The permitted intervals depend on the specific product. Even if the effect wears off sooner than hoped, the next treatment therefore does not always follow immediately.
For a follow-up consultation, note when the improvement began and when bothersome dampness returned. If the treatment brought you hardly any relief, the diagnosis and other treatment options should also be discussed again. You can find information about what we offer on our page on the assessment and treatment of underarm sweating.
Side effects and important limits
Pain, redness, swelling or bruising can occur at the injection sites. Headache, itching or temporary muscle weakness are also possible. If any symptoms worry you, discuss them with the practice that treated you.
If there is an infection at the intended injection site, no injection may be given there. Conditions that impair the transmission between nerves and muscles, as well as certain medicines, call for particular caution. Please therefore also mention conditions that at first glance have nothing to do with sweating.
During pregnancy and breastfeeding, treatment of underarm sweating with botulinum toxin is generally postponed. The available data are not sufficient to confirm that its use is safe. If you experience difficulty swallowing, speaking or breathing after an injection, you need medical help immediately.
Frequently asked questions
Will my underarms be completely dry afterwards?
That is possible, but it cannot be expected for everyone. The aim of treatment is a clear reduction in bothersome sweating. Even a partial reduction can make daily life easier. How pronounced the effect is for you only becomes clear over time.
Does the smell of sweat also disappear?
Less moisture does not automatically mean that all odour disappears. Excessive sweating and body odour are different problems. Deodorant can therefore still play a role. Ask the practice when you can use it again after the injections.
Will I sweat more in other places instead?
The treatment targets the underarms and does not stop sweating on the rest of the body. Increased sweating outside the underarms has been described as a possible side effect. It affects only a small proportion of those treated. Let us know if you notice such a change.
Can I make the effect last longer myself?
No particular skincare product or lifestyle can be relied on to extend the effect. Follow the aftercare advice you were given and review how things are going with your doctor. That is the best basis for planning the next treatment.
Do these timings also apply to the hands?
The information in this article relates to the underarms. Other parts of the body need their own assessment. With the hands in particular, pain during the injections and possible temporary muscle weakness have to be considered. Experience with underarm treatment therefore cannot simply be transferred.
This article does not replace a medical examination.
