Allergen testing is a laboratory method to find out some sensitizing substances that induce allergic reactions in the body. Clinical judgments can be made through prick test, patch test, serological investigation of antibodies and other methods. 1. Prick test. The prick test is a method that uses a specially prepared test solution to prick the patient’s skin under the skin to determine whether there is any allergy according to the reaction of the pricked area. The skin prick test is suitable for patients with allergic rhinitis, asthma, cough, atopic dermatitis, some urticaria, and allergic conjunctivitis. The skin on the flexor side of the forearm is usually chosen as the test area, the area is cleaned and sterilized, and the test and prick are performed according to the instructions. The test is performed when there are basically no symptoms, negative and positive controls should be set, and when the result is negative, the observation should be continued for 3 to 4 days; it is prohibited when there is anaphylaxis, and antihistamines need to be discontinued for more than 3 days before puncture. 2. Patch test. Plaque test is based on the nature of the subject to configure the appropriate concentration of the dip, solution, ointment or the original as a reagent, to the appropriate amount of method of sticking to the skin, after a certain period of time to observe the body whether it produces an allergic reaction to it. The patch test is the main method used to detect type 4 hypersensitivity reactions. 3. Intradermal test. It can be used to test rapid-type hypersensitivity reaction or delayed-type hypersensitivity reaction, and is currently the most commonly used method for rapid-type sensitization reaction of drugs. Its principle, indications and precautions are the same as the prick test. 4. Serologic test. After centrifugation of the patient’s blood, the substrate of the reaction is combined with the antibody in serology, and then according to the level of the value read by the colorimetric agent, the level of the antibody to the specific sensitizer in the serum is judged, so as to determine what kind of article produces an allergic reaction. Specialized kits are currently available.