Body odour, also known as bromhidrosis, occurs when bacteria on the skin breakdown sweat into acids, which have a bad odour. While sweat is generally odourless, some sweat glands, known as apocrine glands, produce substances (proteins, lipids, steroids), which are broken down by bacteria on the skin to produce odour. These sweat glands are found mostly around the armpit, nipples, genitals and anal region.