Underarm Sweating
Apocrine Gland
The apocrine gland is one of the two main sweat glands, and it is the one that makes the underarm distinctive.
Apocrine glands are sweat glands concentrated in areas such as the underarms and groin. They release a thicker, richer secretion than eccrine glands, respond to stress and hormones rather than mainly to heat, and are central to how body odor forms.
What an apocrine gland is
Apocrine glands are a type of sweat gland found in specific areas — most notably the underarms and groin — rather than across the whole body. They open into hair follicles and release a thicker, protein- and lipid-rich secretion, quite different from the watery sweat that cools you.
They become active around puberty, under hormonal influence, which is part of why body odor and heavier underarm sweating tend to appear in the teenage years.
Their role in odor
On its own, apocrine secretion is nearly odorless. Body odor develops when skin bacteria break that secretion down into stronger-smelling compounds. Because apocrine glands are concentrated in the underarm, that is the classic site for this process.
Apocrine versus eccrine
The other main type, the eccrine gland, is spread across the body and makes the watery sweat that cools you in response to heat. Apocrine glands respond more to emotion and hormones. The underarm is unusual in having both in abundance.
Frequently asked questions
What do apocrine glands do?
They release a thick, rich secretion in response to stress and hormones, mainly in the underarms and groin. That secretion is odorless until skin bacteria break it down, which is how body odor forms.
When do apocrine glands become active?
They largely switch on around puberty, under hormonal influence, which is why body odor and heavier underarm sweating tend to emerge in the teenage years rather than in early childhood.
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.