OPRM1 and allergic disease: Tsai FF found that the mu opioid receptor gene (OPRM1) polymorphism was associated with the incidence of EMIP and that the recessive allele G in A118G might have a protective effect in cases of severe pruritus.[19,20] Our finding of allergy as a strong risk factor of EMIP lays foundation to further research regarding the prevention and treatment of pruritus.