Sweating (also known as perspiration or diaphoresis) is controlled by the autonomic nervous system in the brain. When needed, signals are sent to the sweat glands in the skin, which are located all over the body, particularly numerous in the armpits, face, head, palms of the hands and soles of the feet. The sweat glands are then stimulated to produce sweat. On average, they produce 200-700 ml of this salty secretion (sweat) daily, and even more than a litre per hour during extreme exertion.

Sweat is always produced when the body needs cooling down and has to protect itself from overheating. Sweating creates what's known as evaporative cooling, which provides the body with a pleasant cooling effect. When sweating, small droplets of fluid, produced by the sweat glands, pass through the skin's pores to the surface and evaporate immediately in the outside air. And it's precisely this evaporation that creates the cooling effect. The sweating process is regulated by the central nervous system and the release of certain messenger substances.

Through sweating, the body not only loses fluid, but also salts and minerals. Excessive salt loss due to increased sweat production - for example, in a hot summer or during very strenuous physical activity - can lead to significant problems in the body's electrolyte balance. "If you want to sweat less, you should also drink less" is an absolute myth and NOT true! Anyone who sweats a lot absolutely must drink a lot - and if you sweat heavily, don't forget to replenish your minerals too.

What exactly is sweat?

People who sweat easily, or more than others, find it an unpleasant nuisance. You can see it, sometimes you can smell it, and it makes you feel uncomfortable. But nature had a reason for equipping us and other mammals with sweat glands: these glands secrete a watery fluid - sweat - through the skin.

Sweating serves several purposes and is even responsible for whether we find someone likeable or not. You can find out more about the reasons in our guide "Why do we sweat?". Sweat glands are divided into two types depending on how they secrete: eccrine & apocrine sweat glands.

Eccrine sweat glands - the sweat producers

When we talk about sweat glands, we usually always mean the so-called eccrine sweat glands. These produce the typical sweat, namely the clear, salty and rather odourless liquid that is produced, for example, during exertion, heat or even stress.

They are therefore the actual sweat glands and are responsible for "sweating" and thus for regulating body temperature. They are distributed all over the body in a considerable quantity of 2 - 4 million.

People with darker skin have about twice as many. These glands produce a clear, odourless sweat that evaporates on the skin's surface. This creates evaporative cooling, which protects our body from overheating. Eccrine sweat glands can be described as the body's "air conditioning" and the sweat produced as the "coolant".

Sweat consists of more than 99% water and otherwise mainly electrolytes:

• Salts: potassium, sodium, calcium, magnesium, zinc, iron, bicarbonate, sulphate and phosphate
• Acids: amino acids, acetate, pyruvate and lactate
• Hydrophilic substances: urea, proteins, ammonia

The pH value is in the acidic range of 4.5. This allows it to have an antibacterial effect and support the formation of the skin's so-called acid mantle.

Apocrine sweat glands - the scent producers

Apocrine sweat glands are only found in certain areas of the skin - such as the armpits, genital and perineal area or the areola of the nipples, and play a rather minor role in sweating as a cooling function.

They only develop during puberty and are also known as "scent glands". They produce small amounts of a milky secretion that contains proteins and lipids and is almost pH-neutral (pH value 7.2).

Their main function is to create one's own individuality:

Everyone has their "own" smell, which certainly plays a big role in choosing a partner. It's not for nothing that there's the saying: to be able to get on well with someone.

These are very odour-active substances that stick stubbornly to the skin's surface. Due to the onset of moistening by the sweat from eccrine glands, these fragrances are released into the environment.

The secretion of the apocrine glands is hormonally controlled. The activity of these glands usually starts during puberty. This also explains why adolescents often leave behind a typical musty, rancid sweat odour.

How does sweat odour develop?

Fresh sweat is almost odourless. If it starts to smell unpleasant, the culprits are usually bacteria living on the skin, for whom sweat serves as a food source. Bacteria are not always bad in principle, but what they do with our sweat is rather annoying and unwanted. The bacterial decomposition process produces the typical smell, which is not only unpleasant for those around us. The bacteria break down long-chain fatty acids into smaller molecules such as butyric acid or formic acid.

Butyric acid is a fatty acid that has a very unpleasant smell, similar to that of rancid butter. So it's no wonder that this sweat doesn't "smell nice" to our noses, but rather comes across as pungent.

Sometimes fresh sweat does smell!

If a teenager suddenly smells unpleasantly "musty", it's due to hormonal changes. During this time, even fresh sweat can smell unpleasant. You can find out why this is the case here: Sweating during puberty.

Where on the skin do the glands produce sweat?

You might be surprised, because a particularly large number of eccrine glands are found on the soles of the feet, the palms of the hands and the forehead. Be honest, you expected the armpits to be in first place, didn't you? But see for yourself where on the body how many glands are actually located.

Sweat gland-rich zones:

In areas of the body where there are many sweat glands close together, a person sweats heavily under certain circumstances. However, this does not automatically mean that they sweat the most in these areas.

Sweat gland-free zones:

• Lips
• Nail bed
• Glans penis
• Clitoris
• Labia minora
• Eardrum

Also important to know!

In areas of the body where there are many sweat glands close together, a person sweats heavily under certain circumstances. However, this does not automatically mean that they sweat the most in these areas.

We can best illustrate this with our own experience: if you have problems with excessive sweating and dampness, where are your problem areas usually? Aren't they more likely to be the armpits? And that's despite the fact that we have significantly fewer sweat glands under our arms than in other areas of the body…

To prevent excessive sweating, antiperspirants can be used, or deodorants to mask the odour. You can find out the difference between an antiperspirant and a deodorant in this guide HERE.

If you have any further questions about sweating & sweat odour, the EVERDRY team will be happy to help.

First published: 12.05.2011

Updated: 27.05.2025