Apparatus for the transdermal administration of a product in the fluid state comprising a handpiece provided with a support structure within which a laser source is positioned, the handpiece comprising a cartridge positioned in proximity to a first end thereof and containing said product in the fluid state, preferably in gel form, the cartridge having a tubular external casing perforated on its bottom, and a piston sealingly slidable in said tubular casing； the casing, on the side opposite said bottom, having a ball-shaped applicator for distributing the contents of said cartridge, said ball and said piston being made of a material that is transparent or semi-transparent for the light of said laser.
