What Causes Armpit Sweat?

Candace Goforth Desantis

Armpit sweat occurs when the body overheats as a result of physical activity or increased temperatures. Psychological, emotional, or hormonal stimulation also can cause underarm perspiration. Nearly all parts of the body perspire, but underarms tend to sweat more profusely because they have a higher concentration of sweat glands.

An antiperspirant can help with sweating.
An antiperspirant can help with sweating.

Perspiration is the body's built-in cooling system. It also hydrates the skin and balances the body's fluids and electrolytes. When the body overheats, glands beneath the skin release sweat. As air passes over it, the moisture evaporates and cools the skin. Armpits are tucked inside the body and have little exposure to airflow, so sweat tends to pool there.

A diagram of the human skin, including sweat glands.
A diagram of the human skin, including sweat glands.

Sweat glands are controlled by the sympathetic nervous system, which is responsible for the body's fight-or-flight response. When that system is stimulated, as in moments of fear, embarrassment, or nervousness, armpit sweat may increase. Hormonal changes, such as puberty, pregnancy, and menopause, also can bring on a surge of underarm perspiration.

Certain areas, such as the armpits, experience high amounts of sweating.
Certain areas, such as the armpits, experience high amounts of sweating.

Normally, when people cool down, relax, or leave a stressful situation, they stop sweating. For some people, constant and excessive armpit sweat can occur spontaneously. This condition, known as axillary hyperhidrosis, can become so severe that it interferes with daily activities. It can cause perspiration to drip from underarms and soak through shirts even when the person is at rest and in a cool environment.

Sweating works to cool the body off.
Sweating works to cool the body off.

Excessive sweating confined to the armpits is believed to be genetic, and there is no known cause. Generalized hyperhidrosis, however, is an inordinate increase in sweating over the entire body and can be caused by a variety of factors. Certain medications, obesity, alcohol, and cigarettes are known culprits. Other causes include overactivity in the sympathetic nervous system and illnesses such as lymphoma and endocarditis.

There are more than 2.6 million sweat glands throughout the human body. Eccrine glands are those that occur over most of the body. They excrete fluid composed mostly of water and salt with trace amounts of electrolytes. The sweat glands in the armpits are called apocrine glands. They are larger and deeper than eccrine glands, and they also produce a thicker, fatty secretion made up of protein and carbohydrates.

Sweat from apocrine glands contains pheromones, chemicals that stimulate sexual arousal through the sense of smell. The components also cause the yellow coloration in armpit sweat that tends to stain shirts. The bacteria on skin breaks down this sweat, causing the unpleasant odor associated with underarm perspiration.

Generalized hyperhidrosis, or excessive sweating all over the entire body, is caused by a variety of factors.
Generalized hyperhidrosis, or excessive sweating all over the entire body, is caused by a variety of factors.

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Discussion Comments


@burcidi-- You don't want to stop armpit sweating! It's natural and necessary for the body to function properly.

If you're having odor issues, there are many ways to resolve this. You should shower often and wear deodorant that prevents the development of bacteria because it's bacteria that causes odor, not the sweat itself.

You can also try removing armpit hair if you don't already. Armpit hair can hold onto sweat and increase bacteria causing more odor.


Is there a way to stop armpit sweating?


My friend who is also my coworker has hyperthyroidism. Her body produces too much thyroid hormones and this is also affecting her sweat production. I've known her for several years, and I know that she didn't have an excessive armpit sweating problem before. Ever since she developed this condition, she is sweating profusely.

Our office is not that hot in winter and it's very cold in the summer because of the air-conditioning. Everyone wears long-sleeves in the office year-round except her. She wears sleeveless and still, I see her sweating and trying to cool down!

She is taking medications and I hope she gets well soon. I know it's very frustrating for her to be going through this. I wanted to share this here because some people get grossed out when they see people who sweat so much. But this is not normal, it's a medical condition and we shouldn't forget that.

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