The invention relates to a composition including a mixture of a chitosan formulation and a coagulable fluid, in which the chitosan formulation has a chitosan concentration of at least 2.5 wt% relative to the total weight of the chitosan formulation, said chitosan having a dynamic viscosity no greater than 60 mPa.s, measured in 1% acetic acid (v/v), said composition including at least one organic sugar or polyol salt. The invention relates to a medical device.