Occlusion refers to the impervious-to-water covering of the skin directly or indirectly by various means, including tape, gloves, impermeable dressings, or even transdermal devices [1]. Certain topical vehicles, for example, petrolatum or parafn, contain fats and/or polymer oils that may generate occlusive effects by reducing water loss [2]. The epidermis of healthy skin provides an efcient barrier against the inltration of exogenous and potentially harmful substances, and the stratum corneum typically has a water content of 10%–20% by weight. Skin occlusion increases the water content of the stratum corneum up to 50%, and even a short-time occlusion (30 min) results in signicantly increased hydration [3-5]. By increasing stratum corneum hydration, occlusion inuences percutaneous absorption by altering the partitioning between the chemical penetrant and the skin, swelling corneocytes and possibly altering the intercellular lipid phase organization, increasing skin surface temperature, and increasing blood ow [4-6].