Cold urticaria is divided into acquired (primary and secondary) and familial cold, with primary acquired cold urticaria being the most common. Acquired urticaria: 1, primary: this type is the most common, when encountering cold air, liquids, objects, etc., the contact area within a few minutes, accompanied by itching edema and wind masses, in severe cases, non-contact areas can also be involved, patients swimming in cold water or cold shower, can appear skin flushing, hypotension, even fainting and other systemic symptoms similar to histamine shock; 2, secondary: certain sufferers such as cold fibrin Hemoglobinemia, cryoglobulinemia, macroglobulinemia, syphilis, certain connective tissue diseases, bone marrow malignancies, infectious mononucleosis, viral hepatitis B or C and other underlying diseases can occur in patients with cold urticaria. 3, familial cold urticaria: there is a clear family gathering phenomenon, since the onset of infancy, often lasting a lifetime. The rash lasts for a long time (24-48 hours) and is accompanied by a burning sensation and systemic symptoms such as fever and arthralgia. Patients with cold urticaria should be careful to avoid cold stimuli in their lives, and in severe cases, they can seek medical attention to find specific triggers.