An aqueous micellar formulation for localised topical application to an animal for the concurrent control of internal and external parasites in and on the animal, the formulation comprising a water-miscible co-solvent, a fatty alcohol alkoxylate, a macrocyclic lactone and water. Also described is a method for the concurrent control of internal and external parasites in and on an animal, the method comprising administering to the animal by localised topical application an aqueous micellar formulation comprising a macrocyclic lactone.
