odour; BO; perspire; perspiration; sweating; eccrine; glands; apocrine; puberty;
What is sweat?
Our bodies have their own air-conditioning system. It's called sweating.
Sweat flows out through the skin to cool us down if our body temperature is getting higher than the usual 37º Celsius.
Sweat is also known as perspiration.
- We sweat (perspire) to cool our skin and release heat from our body when the hypothalamus (say hippo-thal-a-mus), (the part of the brain that looks after body temperature) sends messages to our body to start sweating. This could be in hot weather or after hard exercise.
- If you have a fever it's because your body is fighting an infection and having a higher body temperature is one of the ways the body does this. While your body is pushing up your temperature you will not sweat, but when your body needs to cool down again you can become very sweaty.
Where does it come from?
There are two types of sweat glands.
The eccrine glands (say ek-reen) are found all over the body in the deeper layer of the skin (the dermis). There are over 2 million of them. There are lots of them on the palms of our hands, the soles of our feet, our armpits and on our scalp.
Each gland has its own exit to the skin's surface. This is called a pore.
If you lick your arm you can taste your sweat. It tastes salty. Sweat from eccrine glands is made out of water, a little bit of salt and tiny amounts of some other chemicals.
The apocrine sweat glands (say ap-oh-kreen) are found in armpits and in the genital and anal area (your 'private' bits). The exit of these glands is into a hair follicle – they do not have their own pore. These glands start working when you reach puberty. They make a thick, oily fluid different to the sweat on other parts of your body.
Why sweat smells
Well actually sweat from the eccrine glands does not have a smell. Sweat from apocrine glands does have a smell, but it is usually only a very slight smell.
But our bodies have bacteria (germs) living on skin and clothes. These bacteria use sweat to grow.
A lot of body smell (body odour or BO) comes from the bacteria feeding on the oils in sweat under the arms or groin. This sweat gets onto the clothes we wear and if we don't wash and change underclothes then the smell gets stronger!
But the worst smell can be from our feet! Feet make a lot of sweat and bacteria can get a really good feed if they hang out inside your socks and shoes. (If your feet are damp then fungi can grow and you could get tinea, which is a fungus.)
Spicy foods and garlic can change the smell of sweat too.
Everyone has their own personal smell - that's how dogs can track people after sniffing a piece of their clothing.
How do you know if you're smelly?
Your nose very quickly gets used to smells around it, so you don't notice your own body smell, but if you are a nearly teen and stick your nose under your arm you might notice a smell. Usually this smell is not as strong or as bad as most people fear it is if you wash regularly and change your clothes.
However – your feet!!! You can notice when your feet smell bad.
Sometimes if people tell you that you smell bad – have BO – they might be being unkind rather than truthful.
Sometimes the things that people use to hide their body smell have a much stronger and more unpleasant smell than their body actually has.
What you can do
Our topic on Personal hygiene has lots of ideas which can help.
Just remember these things.
- If you can, wash your body every day and change your underwear every day.
- Air your shoes, especially sneakers or sports shoes when you take them off. Leave them overnight in the laundry or even outside if you have a covered area where you can safely leave them.
- If you wear a school uniform hang it up when you take it off. Hang it in a place where it can get a passing breeze if possible.
- Kids who have not yet reached puberty do not need antiperspirants and deodorants because their sweat is not smelly. Clean clothes are the most important way to smell nice.
- If you are a 'nearly teen', deodorants, antiperspirants and other smell nice products work best if your skin is clean. Be aware that some perfumes and sprays can make some people feel unwell even though they are not the ones wearing them.
- Clean your teeth twice a day. Your mouth doesn't sweat but bacteria can make your breath smell bad.
Dr Kim says
Drinking tap water is usually enough to replace water lost by sweating. Sports drinks which replace body salts lost during sweating are not needed unless you are in a long hard game where you are running a lot of the time.
Did you know?
- Animals, birds and insects have sweat glands which make pheromones (fer-o-moans). The smell of pheromones attracts animals to each other, eg male rats to female rats, and mothers and their young. They help ants from the same nest to recognize each other.
- The oils in human armpit sweat contain pheromones which we cannot smell. Some people think that humans are most comfortable with people who make pheromones that they subconsciously like, even though we are not aware of these smells.
- Men sweat 40% more than women. It's because the female body is better able to keep a constant temperature.
- Most of a cow's sweat glands are on its nose.
- Dogs and cats control their body temperature by panting (breathing fast). They don't have sweat glands all over their body like humans do.
- Sweating like a pig isn't true. Pigs also don't have lots of sweat glands which is why they like to roll in mud to keep cool.
- A hippo's sweat is red. The red stuff stays on the skin and acts as a kind of sunscreen.
- In the 'olden days' people thought that washing their bodies could make them weak so they didn't! Even the really rich people might only have a bath once a year!
- We can start sweating after eating spicy foods, such as foods which have a lot of chilli in them. This is not because spicy foods make our body hot, but because somehow our brain is tricked by messages going to it from pain sensors on the tongue. Chillies actually burn our tongue!
- Hot drinks can also trigger these pain sensors and make our brain think we are getting too hot and this can cause us to sweat.
We've provided this information to help you to understand important things about staying healthy and happy. However, if you feel sick or unhappy, it is important to tell your mum or dad, a teacher or another grown-up.