Why does sweat cause bad odor?

Q:Why do we need B.O.? Everything in nature has a purpose, except B.O. . . . Do something good, hard work, exercise, smell very bad . . . . You move, you stink. Why can't our bodies help us? Why can't sweat smell good?

- Comic Jerry Seinfeld
A: B.O., formally known as bromhidrosis, results from sweating, which is your body's way of cooling itself when overheated. B.O. usually starts to be a problem during puberty - when teens' bodies are changing and they're already self-conscious.

During puberty, the increasing androgen hormones in boys and girls increase the activity of the sweat glands and alter the chemistry of sweat. Sweat serves as food for skin bacteria, and body odor develops. It's not just in the underarms; teens start perspiring in the scalp, upper thighs, groin, anal area, and the feet.

Teens need to have a bath or shower every day. Poor hygiene can cause skin breakdown so bacteria and viruses can gain access to deeper layers of the skin, causing infections such as impetigo, boils, and abscesses.

Sometimes excess sweating is a symptom of another medical problem.

Social sweating may occur with social anxiety, social phobias or panic attacks. Behavioral therapy, antidepressants, and anti-anxiety drugs may help.

Hyperhidrosis causes excessive sweating even while someone is inactive. Prescription antiperspirants, Botox injections, and even surgery are options.

Cholinergic urticaria happens in people who have an allergic reaction to their own sweat, causing hives. Antihistamines or steroids may be given.