Compositions for generating antimicrobial activity are described. The compositions comprise: a first phase; a second phase; an enzyme that is able to convert a substrate to release hydrogen peroxide; and a substance that includes a substrate for the enzyme, wherein the first phase and the second phase are immiscible. The compositions may be formulated as emulsions or creams. Methods of making the compositions are described, as well as their use for the treatment of antimicrobial infections.