What is Redken Extreme Shampoo? This hair strengthening shampoo cleanses, strengthens and fortifies weakened areas. It also restores and repairs damaged hair while protecting hair's natural shine. Formulated with Redken's Strength Complex which contains Amino Acids and Arginine to strengthen and fortify the hair, and Citric Acid to condition and add smoothness. Using the full system with Extreme's Shampoo, Conditioner and Anti-Snap will help your hair to have a 73% decrease in breakage* and become 3x stronger.