A biological detergent is a detergent used for washing clothing that contains enzymes. The description is commonly used in the United Kingdom, where other washing detergents are described as "non-biological". The terms are sometimes abbreviated to bio and "non-bio".
The purposes of the enzymes is to break down protein, starches and fat that may be found in dirt and stains upon clothing to be laundered, for example food stains, sweat or mud.
Some people may be allergic to the enzymes. The selling points of non-biological detergents is that they are gentler, causing less irritation to skin ("kinder on the skin") and less damage to the fabric. Some studies refute the claim that non-biological detergents are gentler.