When mometasone is applied to the skin it works by acting inside the skin cells to decrease the release of these inflammatory substances. This reduces swelling, redness and itch. Mometasone is a potent corticosteroid that is applied to the skin to treat severe inflammatory skin disorders, such as dermatitis and psoriasis that have not responded to milder steroids. The active ingredient is formulated in a moisturising base that provides a layer of oil on the surface of the skin, helping to prevent water from evaporating from the skin surface. This helps reduce the dryness, scaling and itching of these skin conditions.