Atopic dermatitis (AD) is a chronic or chronically relapsing, eczematous, severely pruritic skin disorder associated with skin barrier dysfunction. The lesional skin of AD exhibits T helper 2 (T H 2)-deviated immune reactions. Interleukin-31 (IL-31), preferentially produced from T H 2 cells, is a potent pruritogenic cytokine, and its sys- First-line treatments of AD include the application of emollients for dry skin, topical steroids, and tacrolimus for skin inflammation, followed by second-line adjunct therapies such as systemic cyclosporine, short-term oral steroids, and ultraviolet radiation.