We are always sweating but many things cause us to sweat more than usual. Hot weather, exercise and doing something that makes us feel anxious all cause the sweat to flow. Sweating is one of the body’s ways of cooling down and it is important that we do sweat. There is a very rare condition where people do not sweat, and they are at a very high risk of overheating.
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There are two types of sweat glands.
The most common type of sweat glands (eccrine glands) are spread all over our body and they produce sweat that is mainly salt and water. This sweat helps keep your body at the right temperature.
You have more than 2 million eccrine glands!
When this sweat evaporates, it cools your body down.
During hot weather you will sweat more.
Hot drinks, drinks that contain alcohol or caffeine, and spicy foods can also make you sweat more than usual.
Having a fever is part of the way that a body fights an infection. Your temperature drops when your body is recovering from the infection. If you have a fever, your body cuts down the amount of sweat that you make (keeping your temperature high). When your body is ready for its temperature to drop you may sweat a lot (this is sometimes called ‘breaking of the fever’).
If you are dehydrated – perhaps it is hot weather and you have not had enough to drink, or you have been ill with diarrhoea and vomiting – you will make less sweat than usual.
We also have sweat glands (apocrine glands) in certain places, such as under the arms and in the groin, which make oils as well as ordinary sweat. These glands only start making the oils after the beginning of puberty.
These sweat glands make sweat at the same times as the eccrine glands, and they make even more sweat when you are stressed.
Sweat by itself does not have much of an odour. Most of the smell is caused by bacteria which live on the skin and in clothing. These bacteria use the sweat for growing.
The sweat on most of our body is not full of food (nutrients) for bacteria, so the bacteria there do not cause a lot of smell.
The only place where there is often a smell from this eccrine kind of sweat is the feet. When feet are covered by socks and shoes, bacteria can really get to work and produce a lot of unpleasant smells. If your feet are damp, yeasts can grow as well as bacteria and they can make a different unpleasant smell.
When sweat gets onto clothes, bacteria can also grow there, making the clothes smelly too.
Most body odour is produced by bacteria feeding on the apocrine sweat from under the arms and in the groin.
Some foods that we eat, such as garlic and spicy foods, can change the smell of sweat.
We all have our own particular scent. This is why dogs can track a particular person by their scent. Have you noticed that perfumes and deodorants don’t always smell the same on different people? That’s because of our different scents.
How do you know if you have unpleasant body odour?
Strange as it may seem, people with unpleasant body odour are unable to smell their body odour. Because they live with it all the time, they are no longer sensitive to the smell. (They can still smell smelly shoes!)
Most people do not have an unpleasant smell, but many people are very anxious that they may have an unpleasant body smell.
You may have an unpleasant smell if you do not wash under your arms and in the groin area at least once a day, if you wear the same clothes day after day and they don’t get washed often, or you wear the same shoes day after day.
Sometimes people have a smell caused by a health problem. People with diabetes for example may have a fruity smell, while people with kidney or liver disease may have an ammonia smell.
How to prevent bad body odour
Wash your body regularly, especially underarms, groin and feet. Dry your feet completely after you have washed them.
Change and wash your clothes often.
Let your shoes dry completely before wearing them again. If possible, wear different shoes on alternate days.
Cotton socks might be better than synthetic socks, but the most important thing is to wash your feet daily, and change your socks daily if possible.
If someone has told you that you have an unpleasant body odour, and you think that might be true, you could try an antibacterial soap when you wash your body. Most people do not need this.
Deodorants and anti-perspirants
Once you start going through puberty, it may be a good idea to start using underarm deodorants and anti-perspirants.
Underarm deodorants make the sweat acidic which stops bacteria from growing. We still make the same amount of sweat, but there are fewer bacteria to make the smell.
Anti-perspirants block the sweat ducts with aluminium salts, so that less sweat is produced. Less sweat equals fewer bacteria and less smell. They should only be used on underarms – you need to be able to sweat over the rest of your body to keep yourself healthy.
There is no evidence that these products are linked to any health problems.
Some deodorants are highly perfumed. Make sure that you are not replacing one smell with another one that other people will not enjoy either.
Some people may be allergic to deodorant sprays and perfumes, so don’t spray them around other people in change rooms.