Shower gels, on the other hand, generally contain the same basic ingredients: water, a foaming ingredient (often sodium laureth sulfate, or SLS), and betaines, the chemical components that help it all stick together. SLS is a bit of a controversial ingredient lately, with more natural brands eschewing the foam-maker in favor of a less sudsy formula (this is the principle behind sulphate-free shampoo, too!). And while SLS has been rated non-carcinogenic by the U.S. Occupational Safety & Health Administration (OSHA), the International Agency for Research on Cancer, and the National Toxicology Program, it may irritate skin if not washed off properly. Some people are more sensitive than others; if that’s you, go with SLS-free shower gel.