SLS stands for Sodium Laureth Sulfate. It is a harmful synthetic detergent and foaming agent. It is used in soaps and shampoos to create lather and to promote effective cleansing. On the other hand, parabens are a chemical that increases the shelf life of the soap and prevents bacteria growth. Both SLS and Parabens are harmful to the skin as they strip off the natural oil from the skin. Also, these chemicals can irritate the skin and eyes. So make sure your soap does not have SLS and parabens.