Sweating is our body's way of cooling down, a bit like an internal air conditioner.
Author
- Michael Freeman
Associate Professor of Dermatology, Bond University
When our core temperature rises (because it's hot outside, or you're exercising), sweat glands all over our skin release a watery fluid. As that fluid evaporates, it takes heat with it, keeping us from overheating.
But sweating can vary from person to person. Some people might just get a little dewy under the arms, others feel like they could fill a swimming pool (maybe not that dramatic, but you get the idea).
So what's a normal amount of sweat? And what's too much?
Why do some people sweat more than others?
How much you sweat depends on a number of factors including:
your age (young kids generally sweat less than adults)
your sex (men tend to sweat more than women)
how active you are.
The average person sweats at the rate of 300 millilitres per hour (at 30°C and about 40% humidity). But as you can't go around measuring the volume of your own sweat (or weighing it), doctors use another measure to gauge the impact of sweating.
They ask whether sweating interferes with your daily life. Maybe you stop wearing certain clothes because of the sweat stains, or feel embarrassed so don't go to social events or work.
If so, this is a medical condition called hyperhidrosis , which affects millions of people worldwide.
People with this condition most commonly report problematic armpit sweating, as you'd expect. But sweaty hands, feet, scalp and groin can also be an issue.
Hyperhidrosis can be a symptom of another medical condition, such as an overactive thyroid , fever or menopause .
But hyperhidrosis can have no obvious cause, and the reasons behind this so-called primary hyperhidrosis are a bit of a mystery. People have normal numbers of sweat glands but researchers think they simply over-produce sweat after triggers such as stress, heat, exercise, tobacco, alcohol and hot spices. There may also be a genetic link.
OK, I sweat a lot. What can I do?
1. Antiperspirants
Antiperspirants, particularly ones with aluminium , are your first line of defence and are formulated to reduce sweating. Deodorants only stop body odour.
Aluminum chloride hexahydrate , aluminium chloride or the weaker aluminum zirconium tetrachlorohydrex glycinate react with proteins in the sweat glands, forming a plug. This plug temporarily blocks the sweat ducts, reducing the amount of sweat reaching the skin's surface.
These products can contain up to 25% aluminium. The higher the percentage the better these products work, but the more they irritate the skin.
2. Beat the heat
This might seem obvious, but staying cool can make a big difference. That's because you have less heat to lose, so the body makes less sweat.
Avoid super-hot, long showers (you will have more heat to loose), wear loose-fitting clothes made from breathable fabrics such as cotton (this allows any sweat you do produce to evaporate more readily), and carry a little hand fan to help your sweat evaporate.
When exercising try ice bandanas (ice wrapped in a scarf or cloth, then applied to the body) or wet towels. You can wear these around the neck, head, or wrists to reduce your body temperature.
Try also to modify the time or place you exercise; try to find cool shade or air-conditioned areas when possible.
If you have tried these first two steps and your sweating is still affecting your life, talk to your doctor. They can help you figure out the best way to manage it.
3. Medication
Some medications can help regulate your sweating. Unfortunately some can also give you side effects such as a dry mouth, blurred vision, stomach pain or constipation. So talk to your doctor about what's best for you.
Your GP may also refer you to a dermatologist - a doctor like myself who specialises in skin conditions - who might recommend different treatments, including some of the following.
4. Botulinum toxin injections
Botulinum toxin injections are not just used for cosmetic reasons. They have many applications in medicine, including blocking the nerves that control the sweat glands. They do this for many months.
A dermatologist usually gives the injections. But they're only subsidised by Medicare in Australia for the armpits and if you have primary hyperhidrosis that hasn't been controlled by the strongest antiperspirants. These injections are given up to three times a year. It is not subsidised for other conditions, such as an overactive thyroid or for other areas such as the face or hands.
If you don't qualify, you can have these injections privately, but it will cost you hundreds of dollars per treatment, which can last up to six months.
5. Iontophoresis
This involves using a device that passes a weak electrical current through water to the skin to reducing sweating in the hands, feet or armpits. Scientists aren't sure exactly how it works.
But this is the only way to control sweating of the hands and feet that does not require drugs, surgery or botulinum toxin injections.
This treatment is not subsidised by Medicare and not all dermatologists provide it. However, you can buy and use your own device, which tends to be cheaper than accessing it privately. You can ask your dermatologist if this is the right option for you.
6. Surgery
There is a procedure to cut certain nerves to the hands that stop them sweating. This is highly effective but can cause sweating to occur elsewhere.
There are also other surgical options, which you can discuss with your doctor.
7. Microwave therapy
This is a newer treatment that zaps your sweat glands to destroy them so they can't work any more. It's not super common yet, and it is quite painful. It's available privately in a few centres.
Michael Freeman is a founder of, and works at, The Skin Centre, a private dermatology practice on the Gold Coast, Queensland. The Skin Centre provides botulinum toxin injections for axillary (armpit) hyperhidrosis.
