The invention relates to a compress with a cooling effect, based on particles (6) of a polymer that has a high water absorption capacity, which comes enclosed with a reserve of water to activate it in an item (2) which comprises, inside a watertight outer sachet (3), on the one hand an inner pouch (4) filled with water and sealed in a watertight manner by a wall comprising a frangible region (10) and, on the other hand, the compress (1) produced in the form of a wrapper (5) at least partially permeable to water and containing the polymer particles (6) in the dry state. The sachet (3) is made of a material of a nature able to keep the pouch (4) and the compress (1) sterile.