This prospective, non-randomized, controlled study evaluated the efficacy of a topical cosmetic keratolytic preparation (serum and cream containing urea, salicylic acid, and collagen) in reducing the thickness and associated pain of hyperkeratotic foot lesions (calluses and corns). High-frequency ultrasonography (18 MHz) was used for precise, quantitative measurement of lesion thickness before and after a two-month intervention. Participants were allocated to four parallel groups (treated calluses, untreated callus controls, treated corns, and untreated corn controls).