Described herein is a solution for use in reducing or inhibiting blood flow in a blood vessel of a subject, wherein the solution comprises water, at least one polycation, at least one polyanion, and a concentration of monovalent ions in water sufficient to prevent association of the polycation and polyanion, wherein the concentration of the monovalent ions in the solution is greater than the concentration of the monovalent ions in the blood vessel of the subject, whereupon introduction of the solution into the vessel the solution is converted to a solid in situ within the vessel.
