Allergens, also known as allergens, are detected mainly by skin tests and serum specific IgE (SIgE). The skin test was introduced in 1909 and is simple, rapid, low cost and highly sensitive, mainly divided into two types of intradermal and prick tests. 1, intradermal test: the classic method of skin testing, the results are more reliable, the test dose control is more strict. In recent years, this method has been gradually replaced by the puncture test because it is tedious, painful and not suitable for pediatric patients. 2, puncture test: puncture test is a simple skin test to introduce the antigen into the skin more superficial. The test is performed by first putting a drop of allergen solution on the skin of the subject’s flexor side, and then using a sterile prick needle to prick the skin in the center of the antigen drop. 15-20 minutes to observe the results. A negative control was set up at the same time as the test. The results of the prick test are determined by the size of the papule. Serum specific IgE test: For in vitro diagnosis, since the IgE content in blood is very small, only one hundred thousandth of the IgG content in blood, and the specific IgE content is even smaller, the specific IgE content cannot be detected by general immunological methods, and it is necessary to use anti-human IgE antibodies labeled with isotopes or enzymes (as secondary antibodies) and solid phase allergens to establish the labeled immunoassay technique. Determination. The advantages are: 1. It is not affected by allopathic medication and is not disturbed by allergic symptoms; 2. It is suitable for patients with scratch disease who have false positive skin tests, those with severe allergic states, those with severe dermatitis who are unable to perform skin tests, and elderly people and children under 3 years of age who have poor skin response; 3. It is not associated with the general discomfort associated with skin tests with allergens such as insects and animal dander. 4. Evaluation of allergy severity 5. Pre-medication evaluation for those who intend to perform specific immunotherapy. Long-term large amounts of systemic corticosteroids can suppress allergen detection results, but short-term and long-term small doses of corticosteroids have no effect on allergen detection, so it is not necessary to stop taking inhaled glucocorticosteroids for bronchial asthma patients. Topical topical corticosteroids should be discontinued one week before the skin test. Generally, antihistamines should be discontinued for 3 days prior to skin testing, but can skin testing be performed if the history of medication is unknown, or if the objective situation cannot wait despite taking medication? In most cases, a skin test can still be performed. It can depend on the reaction of the positive control. If the histamine reaction is normal, it suggests that the skin reactivity is not affected, and secondly, not every patient’s skin reaction will be inhibited by the drug. Also allergen blood tests do not have to be performed on an empty stomach.