Underarm Sweating
Bromhidrosis
Bromhidrosis is the medical term for noticeable or excessive body odor. It arises when skin bacteria break down sweat (especially the apocrine secretion concentrated in the underarms) into strongly smelling compounds. It reflects the normal odor process turned up, rather than a sign of poor hygiene.
Bromhidrosis is the clinical word for body odor, and understanding it clears up a lot of the shame that can attach to the subject.
What bromhidrosis means
Bromhidrosis simply means body odor that is noticeable or troublesome. It is the same process behind everyday underarm smell (bacteria breaking down sweat into odorous compounds) rather than a separate disease.
It centers on the underarm because that area is rich in apocrine glands, whose thick secretion is the preferred food of odor-forming bacteria, and because it is warm, covered, and often hairy.
Why it happens
Fresh sweat is largely odorless. Bromhidrosis develops when there is more apocrine secretion, more bacterial activity, or conditions that favor both: warmth, moisture, and hair. Diet, hormones, and some medical conditions can influence it too.
It is not evidence of being unclean; it is the ordinary odor mechanism operating strongly.
When to raise it
Persistent, marked body odor, or a sudden change in body odor, can occasionally point to something a clinician should look at, so a noticeable change is reasonable to mention.
Frequently asked questions
What causes bromhidrosis?
Skin bacteria breaking down sweat (especially the apocrine secretion in the underarms) into strong-smelling compounds. Warmth, moisture, and hair encourage it. It reflects the normal odor process turned up, not poor hygiene.
Is bromhidrosis the same as sweating a lot?
No. Bromhidrosis is about odor, not the amount of sweat. Someone can sweat heavily with little smell, or notice marked odor without being especially damp, because odor tracks the apocrine secretion and bacteria rather than watery cooling sweat.
Sources & further reading
The reputable organizations our editorial team draws on for the anatomy, definitions, and safety guidance behind this page, and where you can read more on each topic.
General educational information about sweating. Not medical advice, and not a substitute for diagnosis or treatment by a qualified healthcare professional.