Stridex (originally spelled Stri-Dex) is an acne treatment and prevention medicine. It comes in the form of pads contained in a plastic tub of fifty-five to seventy-five pads. Most products in the Stridex line contain as the active ingredient salicylic acid (0.5–2.5%); Stridex "Power Pads", however, contain instead benzoyl peroxide (2.5%), and were the first acne treatment pads to do so without requiring a prescription for purchase.