Antibacterial agents are sometimes added to soaps and may decrease body odor by inhibiting bacterial action on apocrine sweat . As surfactants, soaps decrease surface tensions in liquids and therefore allow the formation of soap bubbles and lather. Mildness, biodegradability, low toxicity, cleansing ability, emulsification, moisturization, skin appearance and feel and lubrication are all important aspects of soap performance. Surfactants vary in biodegradability and some synthetic forms have caused large fish kills in the recent past. Even some modern surfactants in soaps and shampoos cause skin irritation.
Harsh surfactants deplete natural fats and lipids in the skin.
Soaps destroy the lipid covering of the skin and alter skin pH. These protective features of the skin are natrually restored in several hours. Essential oils and herbal extracts can be added to soaps to soothe the skin, restore moisture, and revive the spirit. All-natural mild cleansers may contain organic detergents occurring in plants, such as the sugar beet, called betaines. Another synthetic class, made of alkylated amino acids, is also mild and is often used in formulations to deliver active ingredients. Alkylamide alkylamines are also mild and are used in hair conditioners and baby shampoos.