Underarm Sweating

Sweaty Underarms: What Causes It?

What actually causes the underarm to sweat? The answer is a specific combination of anatomy and everyday triggers, rather than any single culprit.

Last updated Jul 11, 20262 min read

Quick answer

Underarm sweating is caused by the ordinary work of the sweat glands packed into the area — eccrine glands cooling you in response to heat and effort, and apocrine glands responding to stress and hormones — amplified by the warm, covered, slow-drying environment of the axilla.

The direct causes

The immediate cause is the sweat glands themselves. Eccrine glands release watery sweat to cool the skin whenever you are warm or active. Apocrine glands, unusually concentrated in the underarm, release a thicker secretion in response to adrenaline, nerves, and hormonal signals. The area's warmth and cover then keep that moisture from evaporating quickly.

So “what causes underarm sweating” really has two answers at once: heat-and-effort through the eccrine glands, and stress-and-hormones through the apocrine glands.

The everyday triggers that turn it up

On top of that baseline, common triggers push underarm sweating higher for a while: hot or humid weather, exercise, caffeine, spicy food, alcohol, and stressful or high-attention moments. Hormonal changes — puberty, menstrual cycles, pregnancy, the menopausal transition — can shift it over longer stretches.

Usually more than one of these is in play at once, which is why underarm sweating can feel unpredictable until you have watched your own pattern.

When a cause is worth checking

Most underarm sweating traces back to these everyday causes. Occasionally sweating reflects something a clinician should look at, especially when it is new, one-sided, or paired with other symptoms.

Key takeaways

Underarm sweat comes from eccrine glands (heat) and apocrine glands (stress and hormones) together.
The warm, covered axilla keeps moisture from evaporating quickly.
Everyday triggers and hormonal changes turn it up further.

Frequently asked questions

Can stress alone cause underarm sweating?

Yes. The apocrine glands concentrated in the underarm respond directly to adrenaline and nerves, so a stressful moment can bring dampness that has nothing to do with the temperature.

Do hormones cause underarm sweating?

They can shape it. Underarm sweating often steps up at puberty as apocrine glands become active, and shifts again with menstrual cycles, pregnancy, and the menopausal transition. These changes are a normal part of how the body regulates itself.

Can food or drink cause underarm sweating?

For some people, yes — caffeine, alcohol, and spicy food can each nudge sweating up for a while. The effect varies person to person and is temporary, settling once the trigger passes.

Is underarm sweating worse in summer?

For most people, yes — higher temperatures mean more cooling sweat across the body, the underarm included. It usually eases as the weather cools, which is a sign it is heat-driven rather than anything unusual.

Sources & further reading

Reputable organizations with more on sweating and related topics. Offered for further reading and general education, not as citations for any specific claim on this page.

General educational information about sweating. Not medical advice, and not a substitute for diagnosis or treatment by a qualified healthcare professional.