Iles Formula 6.8 oz. Iles Formula Shampoo The Iles Formula system was developed by celebrity hairstylist Wendy Iles and a team of scientific experts with the purpose of developing INSTANT repair for ALL hair types. Tested globally across Europe, Africa, Middle East, Asia, India, North and South America delivering excellent results. Iles shampoo is sulfate-free, paraben-free and silicon-free being one of the rare sulfate-free shampoos on the market today with an abundance of lather. How to Use.