Myth, sweat smells by itself

Short answer: Fresh sweat is almost odourless. The smell only appears when bacteria on the skin break the sweat down, and that takes a few hours in a warm, damp layer. The fabric against your skin therefore affects how quickly it happens.

Where the myth comes from

Because we often notice odour after a day when we have sweated, it is easy to think that sweat itself smells. But there is usually a gap between the moment you sweat and the moment the smell appears. That is when the real process happens, and it is also where you have a chance to do something about it.

Sweat is water and salts

The sweat from most glands is mainly water with salts and has no smell. It has an important job, cooling the body as it evaporates from the skin. Fresh sweat on clean skin therefore barely smells at all. It is only when the sweat stays in a warm, damp layer that things change, see bestsellers for women.

Bacteria create the smell

Bacteria on the skin turn sweat and skin oil into substances that smell. These bacteria are a normal part of the skin, but they thrive where it is warm and damp. That is why odour usually comes from armpits, feet and places where clothes sit close. The longer sweat stays put, the more time bacteria have, see Copenhagen Bamboo bestsellers.

The fabric sets the pace

A fabric that holds moisture against the skin gives bacteria better conditions. A fabric that moves moisture away and lets it evaporate keeps the surface drier and can delay the smell. That is why many people notice that different tops start to smell at different speeds, even after the same amount of sweating, see bamboo sweats for men and women.

Clothes hold on to odour

Once the smell has formed, it settles into the fabric. Airing a worn top removes some of it, but not all. If clothes sit damp in a laundry basket for days, the bacteria get even more time. Hang worn clothes to dry before they go in the basket, and wash them before the odour sets in.

Wash with care

Ordinary detergents at forty degrees remove sweat and skin oil from most fabrics. Turn clothes inside out, because the inside is what touched your skin. Avoid too much fabric softener, which can coat the fibres and trap odour. Let clothes dry completely before they go in the wardrobe, so no musty smell develops.

Everyday habits that help

Change into a dry layer if you have sweated a lot, for example after cycling. Let shoes and clothes air out before wearing them again, and alternate between two pairs of shoes. A shower removes bacteria and skin oil, so you start the day with clean skin. Small habits like these make a noticeable difference over a long day.

When the smell changes

Body odour varies from person to person and can change with diet, stress and season. That is completely normal. If you notice a marked or sudden change in your body odour, or you sweat much more than before without a clear reason, it is a good idea to talk to your doctor.

Frequently asked questions

Does sweat smell on its own

No. Fresh sweat is almost odourless. The smell comes when bacteria on the skin break down sweat and skin oil, especially in warm, damp layers.

How long before clothes start to smell

Typically four to six hours, depending on temperature, activity and which fabric sits against the skin all day.

Can you delay the smell

Yes. A fabric that moves moisture away from the skin keeps the surface drier and gives bacteria poorer conditions, so the smell appears later.