Acute urticaria is an acute allergic disease with a duration of less than 6 weeks, manifesting itself as an itchy, windy mass that has no fixed location and may subside on its own, or in severe cases, may be accompanied by fever, chills, chest tightness, abdominal pain, etc. Acute urticaria is the most common allergic disease, and the typical rash is a wind cluster, which looks like a mosquito bite, slightly protruding from the skin surface, and can subside on its own within minutes or hours, usually no more than 24 hours, leaving no trace after subside. Recall that before the onset of the disease, there are often triggers such as the consumption of special foods, changes in the external environment. A part of the more serious urticaria, which is caused by infection, has a rapid onset and heavy allergic reaction. When accumulating the mucous membrane of the respiratory and digestive tracts, it may cause edema of the respiratory and digestive tracts, and then the recent sensation of chest tightness, throat obstruction, abdominal pain, and in severe cases, anaphylactic shock, which may be life-threatening. This type of urticaria often manifests itself in the early stages as rapid onset, bright red rash that does not fade easily, and in some patients, chills and fever. Because acute urticaria varies greatly in severity depending on the extent of accumulation, it is recommended that prompt treatment be given after detection, with oral imipramine, loratadine, etc. Seek medical attention promptly if fever is present. If the rash does not subside within 24 hours, or traces after subside, or combined with arthralgia, it needs to be distinguished from urticarial vasculitis and needs to be treated by a doctor.