Abstract: The invention relates to a method of treating acne by the topical administration of an acne active ingredient in the presence of a) an anhydrous composition comprising a component that in the presence of water generates heat, and b) water. The invention also relates to an acne treatment kit comprising a first composition which is anhydrous and comprises a component that in the presence of water generates heat on the skin to which it is applied and a second composition which comprises an aqueous carrier, at least one of said compositions comprising an acne active ingredient, said compositions being stored in isolation from each other and being capable of generating heat when they are combined.