Where the smell comes from
You have two kinds of sweat glands. Eccrine glands cover the whole body and release salt water to cool you, and that sweat is nearly odorless. Apocrine glands sit in the armpits and the groin, switch on at puberty and release a thicker sweat that carries proteins and fats. Bacteria on the skin break that down into the compounds you recognize as body odor. Stress triggers the apocrine glands, which is why a job interview smells worse than a three-mile run. Hair holds sweat and bacteria against the skin, so trimming underarm hair reduces odor. Your nose stops registering your own smell within minutes. Sniff the armpit of a shirt an hour after taking it off, or ask someone you trust.
Washing that works
Use soap every day on the armpits, the groin, the feet, the navel, behind the ears and in any skin folds, because water alone does not remove oily apocrine sweat. Dry yourself completely before you dress. For odor that persists, dermatologists often suggest a benzoyl peroxide wash, left on the armpits for a minute or two before rinsing a few times a week, which cuts down the bacteria. It bleaches towels, so use white ones. Antiperspirant works best when it is applied at night to dry skin.
Clothes hold the smell
Polyester and other synthetics hold body oils and odor-causing bacteria far more than cotton, linen or wool do, which is why a clean gym shirt can smell the moment it warms up. Wash workout clothes promptly and inside out, use an enzyme detergent in the measured amount, and skip fabric softener, which coats the fibers and locks odor in. For a shirt that is far gone, soak it for thirty minutes in cold water with a cup of white vinegar before washing. An undershirt protects dress shirts, and merino wool resists odor for days.
When it is medical
Hyperhidrosis is sweating beyond what cooling requires. It affects roughly one person in twenty, usually on the palms, soles, armpits or face. A doctor can offer prescription-strength antiperspirants, medicated wipes, a device that passes a mild current through water for the hands and feet, botulinum toxin injections that last several months, and oral medication. See a doctor promptly for drenching night sweats, sweating that is new or on one side only, sweating with weight loss or fever, or a sudden change in the way your body smells.
Tip Keep a spare shirt at work through the summer. A two-minute change at noon solves what worrying all afternoon cannot.
