One Bottle of Hair Regain Shampoo lasts 6 to 8 weeks depending on usage. NATURAL HAIR REGAIN REGROWTH SHAMPOO. Other shampoos can clog hair follicles with gelatin based thickeners. Hair Regain Shampoo utilizes phyto-revitalizers and essential oils to dramatically increase hair retention and manageability for all types of hair (especially for people who have dyed their hair).