The subject matter of the present invention is a sterile liquid composition dedicated to administration into or through the skin and/or the lips, wherein said composition comprises, in a physiologically acceptable medium, at least one photo-crosslinkable compound, wherein said compound comprises at least one activated photo-dimerizable group having at least one activated double bond and selected from photo-dimerizable groups carrying a stilbazolium function of formula (Ia) or (Ib) and wherein the photo-dimerizable groups carry a styrylazolium function of formula (II), the photo-dimerizable group(s) being carried by a partially or totally hydrolysed poly(vinyl acetate) polymer, a polysaccharide or a polyvinyl alcohol.