In NC/Nga mice stimulated with the 2,4-dinitrochlorobenzen (DNCB) model of atopic dermatitis, oral administration of I3C effectively reduced atopic dermatitis-like skin inflammation by declining serum IgE levels, epidermal thickening, inflammatory cell infiltration, trans-epidermal water loss, and scratching behavior, and decreased proinflammatory cytokine expression, thymic stromal lymphopoietin (TSLP), and periostin against TNF-α- and IFN-γ-induced inflammation in HaCaT keratinocytes. The gene discussed is TSLP; the disease is atopic eczema.