Sodium laureth sulfate, or sodium lauryl ether sulfate (SLES), is an anionic detergent and surfactant found in many personal care products (soaps, shampoos, toothpaste etc.). SLES is an inexpensive and very effective foaming agent.[1] SLES, SLS, ALS and sodium pareth sulfate are surfactants that are used in many cosmetic products for their cleansing and emulsifying properties. They behave similarly to soap. Unfortunately, both sodium laureth sulfate and its cousin are also very dangerous, highly irritating chemicals. Far from giving "healthy shining hair" and "beautiful skin", soaps and shampoos containing sodium laureth sulfate can lead to direct damage to the hair follicle, skin damage, permanent eye damage in children and even liver toxicity.

Although sodium laureth sulfate is somewhat less irritating than SLS, it cannot be metabolised by the liver and its effects are therefore much longer-lasting. This not only means it stays in the body tissues for longer, but much more precious energy is used getting rid of it.