What is the difference between sulfate and sulfonate? The front says 'Sulfate free' but the ingredients list sulfonate. Patient Care March 19, 2020 19:15 Updated Sulfonates are a different chemical structure from “Sulfates”. Shapiro MD products are sulfate free. Related articles Staining effects - Bottle & Hair Safe for long term use? Is it bad if I leave the product in for over 20 minutes maximum period? Do results continue to get better the longer I use the product? I'm using minoxidil. Can this shampoo be combined with it?