Often come on at the same time with nettle rash, also can be in all sorts of infection happen when insecurity of sexual disease, spirit and drug allergy, what happen alone is not scarce also, course of diseases is a bit long.

• 经常与荨麻疹同时发病，也可在各种感染性疾病、精神紧张及药物过敏时发生，单独发生的也不少见，病程稍长。