What is the difference between eccrine and apocrine sweat glands?

Eccrine glands are spread over nearly the whole body, open directly onto the skin, and release a watery fluid that cools you by evaporating. Apocrine glands are concentrated in the underarms and groin, open into hair follicles, and release a thicker secretion that skin bacteria turn into body odor.

How many sweat glands does the body have?

Reviews estimate roughly 2 to 4 million eccrine glands across the body, densest on the palms, soles, and forehead. Apocrine glands are far fewer and are limited mainly to hair-bearing regions such as the underarms and groin.

Which glands cause body odor?

Apocrine glands are the main source of the raw material for body odor, but their secretion is close to odorless when fresh. The characteristic smell appears only after skin bacteria break that secretion down into volatile compounds, so odor is a partnership between the gland and the skin microbiome.

Why do my palms sweat when I am nervous but not smell?

The palms are dense in eccrine glands, which respond to emotion and alertness as well as heat and produce a watery, mostly odorless fluid. Odor is tied to apocrine glands in the underarms and groin, not to the eccrine sweat on the hands.

What is an apoeccrine gland?

It is a third type described in the human armpit that shares features of both eccrine and apocrine glands: it is large but opens onto the skin surface and can produce a lot of watery sweat. Its exact role in normal sweating and in heavy underarm sweating is still debated.

Is this page medical advice?

No. It is an educational summary of normal sweat gland anatomy and physiology drawn from published sources. It does not diagnose or treat any condition; questions about your own sweating are best discussed with a clinician.

Research

Eccrine and Apocrine Glands: The Two Types of Sweat

Human skin contains two principal kinds of sweat gland. Eccrine glands are spread over nearly the entire body surface and produce the watery sweat that cools us, while apocrine glands are concentrated in the underarms, groin, and around the nipples and release a thicker secretion that skin bacteria turn into body odor. A third, hybrid apoeccrine gland has also been described in the human armpit. This page explains how the main gland types differ in structure, location, and function. It is educational and is not medical advice.

By the Sweat Explained Editorial Team · Published 2026-07-20 · Last reviewed 2026-07-20 · Educational information, not medical advice.

Key statistics at a glance

2 to 4 million
estimated number of eccrine sweat glands distributed across the human body
Baker 2019 (Temperature)
Underarms, groin, areola
main regions where apocrine glands are found, opening into hair follicles rather than directly onto the skin
Wilke 2007 (Int J Cosmet Sci)
Acetylcholine
the main neurotransmitter that activates eccrine sweating, which is unusual for a sympathetic nerve
Sato 1989 (J Am Acad Dermatol)
Puberty
the point at which apocrine glands become functionally active, under the influence of sex hormones
Wilke 2007 (Int J Cosmet Sci)
Odorless at first
apocrine secretion has little smell until skin bacteria break it down into volatile odor compounds
Baker 2019 (Temperature)

Two glands, one skin

Not all sweat is the same, and not all of it comes from the same place. The skin carries two main types of sweat gland that evolved for different jobs. Eccrine glands handle temperature control: they pour a dilute, watery fluid onto the skin surface, and its evaporation cools the body. Apocrine glands are far fewer and are tied to hair-bearing regions such as the underarms and groin; their secretion is not primarily about cooling and is closely linked to body odor.

A useful way to keep them straight is by what activates them and what they release. Eccrine glands respond mainly to heat and, at some sites, to emotion, and their fluid is almost odorless when fresh. Apocrine glands respond more to emotional and hormonal signals, and their secretion only becomes smelly after resident skin bacteria metabolize it. Understanding this split explains why a hot day and a stressful meeting can each make you sweat, but not always in the same places or with the same smell.

Eccrine versus apocrine at a glance

The features most often used to distinguish the two main gland types, drawn from sweat-gland physiology reviews (Sato 1989; Wilke 2007; Baker 2019).

Structural and functional differences between eccrine and apocrine sweat glands
Feature	Eccrine glands	Apocrine glands
Location	Almost the entire body surface; densest on palms, soles, and forehead	Underarms, groin, perianal area, and areola (hair-bearing regions)
Number	Roughly 2 to 4 million across the body	Far fewer; a small fraction of total sweat glands
Opens onto	Directly onto the skin surface through a pore	Into a hair follicle, above the sebaceous gland
Secretion	Dilute, watery, mostly water with sodium and chloride	Thicker, richer in proteins and lipids
Main trigger	Heat and, at some sites, emotional stimuli	Emotional and hormonal signals
Function	Evaporative cooling (thermoregulation)	Not primarily cooling; secretion linked to body odor after bacterial breakdown
Active from	Functional in infancy	Becomes active at puberty

These are general distinctions; a third hybrid apoeccrine gland has been described in the axilla and shares features of both types (Sato 1987).

Eccrine glands: the cooling system

Eccrine glands are the workhorses of temperature control. Each is a small coiled tube, with a secretory coil deep in the skin and a duct that carries fluid to a pore on the surface. When core temperature rises, the brain signals these glands to release a watery fluid; as that fluid evaporates, it draws heat away from the body. They are densest on the palms, soles, and forehead but are present over almost the whole body.

A distinctive detail is how they are wired. Eccrine glands are supplied by sympathetic nerves, but unlike most of the sympathetic system they release acetylcholine rather than noradrenaline as their main chemical messenger (Sato 1989). That cholinergic control is why drugs and conditions that affect acetylcholine signaling can change sweating, and it is the basis for tests that stimulate sweat glands directly. Eccrine sweating at the palms and soles is also triggered by emotion and alertness rather than heat alone, which is why hands can turn damp under stress.

Apocrine glands and body odor

Apocrine glands are larger, sit deeper, and empty into hair follicles rather than onto open skin. They are concentrated in the underarms, groin, and around the nipples, and they become active at puberty under hormonal influence (Wilke 2007). Their secretion is oily and protein-rich, and, importantly, it is close to odorless when it first reaches the skin.

Body odor develops in a second step. Skin bacteria break down apocrine secretion into smaller, volatile molecules that carry the characteristic smell (Baker 2019). This is why odor is really a partnership between the gland and the skin microbiome, and why the underarm, with its warmth, moisture, and dense bacterial community, is the classic site. The distinction matters: eccrine sweat is mostly about heat, whereas apocrine secretion is the raw material that the skin's bacteria turn into scent.

The apoeccrine gland: a described hybrid

Beyond the two classic types, researchers have described a third gland in the human armpit. Key points from the primary description (Sato 1987) and later reviews:

Where it is. Apoeccrine glands were identified in the axillae (armpits) and appear to develop around puberty from eccrine-like precursors.
Why the name. They share features of both types: like apocrine glands they are large, and like eccrine glands they open directly onto the skin surface and produce a copious, watery secretion.
Possible role. Because they can secrete at high rates, apoeccrine glands have been proposed to contribute to heavy underarm sweating, though their exact contribution in health and in hyperhidrosis is still debated.
Why it is uncertain. The apoeccrine gland is described in a limited body of work, and not all questions about its prevalence and function are settled, so it is best treated as a recognized but less fully characterized third type.

What this means in plain terms

If you remember one thing, make it this: eccrine glands cool you, apocrine glands are the starting point for odor. The watery sweat that appears all over the body on a hot day is eccrine; the sweat tied to underarm smell is apocrine, and it needs skin bacteria to become smelly at all. The two systems overlap in the underarm, which is why that area both sweats and can carry odor.

Knowing the difference helps make sense of everyday experiences and of the wider research on this site: why palms sweat under stress, why fresh sweat has little smell, and why body odor is as much about skin bacteria as about the glands themselves. This page describes normal anatomy and physiology; it is educational and does not diagnose or treat any condition.

Methodology and limitations

This page draws on peer-reviewed physiology sources: Baker's 2019 comprehensive review of sweat gland function (Temperature), Sato and colleagues' classic account of normal sweat gland biology (J Am Acad Dermatol 1989), the primary description of the apoeccrine gland (Sato et al., Am J Physiol 1987), a history of sweat gland biology (Wilke et al., Int J Cosmet Sci 2007), and an anatomy review of sweat glands (Groscurth, Curr Probl Dermatol 2002). Each numeric or structural claim was traced to those sources.

Limitations: the count of eccrine glands is an estimate with a wide reported range and varies between individuals and body sites, so figures such as 2 to 4 million should be read as approximate. The apoeccrine gland is described in a smaller literature, and its prevalence and functional importance remain debated. This page summarizes general anatomy and physiology; it is educational and is not a diagnosis or medical advice.

Frequently asked questions

What is the difference between eccrine and apocrine sweat glands?: Eccrine glands are spread over nearly the whole body, open directly onto the skin, and release a watery fluid that cools you by evaporating. Apocrine glands are concentrated in the underarms and groin, open into hair follicles, and release a thicker secretion that skin bacteria turn into body odor.
How many sweat glands does the body have?: Reviews estimate roughly 2 to 4 million eccrine glands across the body, densest on the palms, soles, and forehead. Apocrine glands are far fewer and are limited mainly to hair-bearing regions such as the underarms and groin.
Which glands cause body odor?: Apocrine glands are the main source of the raw material for body odor, but their secretion is close to odorless when fresh. The characteristic smell appears only after skin bacteria break that secretion down into volatile compounds, so odor is a partnership between the gland and the skin microbiome.
Why do my palms sweat when I am nervous but not smell?: The palms are dense in eccrine glands, which respond to emotion and alertness as well as heat and produce a watery, mostly odorless fluid. Odor is tied to apocrine glands in the underarms and groin, not to the eccrine sweat on the hands.
What is an apoeccrine gland?: It is a third type described in the human armpit that shares features of both eccrine and apocrine glands: it is large but opens onto the skin surface and can produce a lot of watery sweat. Its exact role in normal sweating and in heavy underarm sweating is still debated.
Is this page medical advice?: No. It is an educational summary of normal sweat gland anatomy and physiology drawn from published sources. It does not diagnose or treat any condition; questions about your own sweating are best discussed with a clinician.

Sources

Primary peer-reviewed studies and official sources first, then reviews and institutional framing (secondary).

Baker LB. Physiology of sweat gland function: the roles of sweating and sweat composition in human health. Temperature (Austin). 2019;6(3):211-259. Comprehensive review covering eccrine and apocrine gland structure, number, and function. Full text
Sato K, Kang WH, Saga K, Sato KT. Biology of sweat glands and their disorders. I. Normal sweat gland function. J Am Acad Dermatol. 1989;20(4):537-563. Classic account of eccrine gland structure and cholinergic sympathetic control. Journal
Sato K, Leidal R, Sato F. Morphology and development of an apoeccrine sweat gland in human axillae. Am J Physiol. 1987;252(1 Pt 2):R166-R180. Primary description of the apoeccrine gland. (secondary) Journal
Wilke K, Martin A, Terstegen L, Biel SS. A short history of sweat gland biology. Int J Cosmet Sci. 2007;29(3):169-179. Reviews eccrine and apocrine gland location, development, and function. (secondary) Journal
Groscurth P. Anatomy of sweat glands. Curr Probl Dermatol. 2002;30:1-9. Anatomy reference for eccrine and apocrine glands. (secondary) Journal

How to cite this page

Sweat Explained. Eccrine and Apocrine Glands: The Two Types of Sweat. Published 2026-07-20; last reviewed 2026-07-20. Available at: https://sweatexplained.com/research/eccrine-vs-apocrine-sweat-glands

Please cite the original studies for the underlying figures. Journalists are welcome to link to this page; the charts are original renderings of the cited data.