Urticaria is a common allergic disease in dermatology, and the examination of allergens is a very important aspect of treatment. It is examined mainly by the following methods: 1. The prick test, which is a relatively common test method, generally chooses the flexor side of the forearm as the test site, puts a drop of test solution on the skin pricked by a special needle, and reads the results about 20-30 minutes later. It is important to note that the prick test is usually performed when there is no clinical manifestation, and saline and histamine positive control group should be available. 2 days before the test, antihistamines, such as loratadine, should be discontinued, and patients during pregnancy should also avoid the test. 2. Blood sampling for specific IgE and related allergens is also a relatively common test method, but it usually takes longer, about 2-3 days to get the results. There are also some hospitals or institutions that use bioresonance to detect allergens, but it is more controversial and is rarely used now.