Desensitization is a method used to treat type I hypersensitivity reactions caused by specific allergens, rendering the body insensitive or unresponsive to the sensitizer. This treatment is mainly done by testing and giving the patient a subcutaneous injection after the type of allergen is accurately detected. Desensitization is essentially a process of establishing tolerance to the allergen for the patient, and the entire process needs to be performed in a specialized hospital. After immunological examination to confirm the diagnosis of the allergen, the preparation is then formulated in different concentrations according to the specific allergen composition. The concentration of the preparation is then gradually increased by subcutaneous injection or sublingual administration, during which the patient can be observed for the degree of violent reaction to the preparation. The concentration that is appropriate for the patient is finally selected and continued for a period of time to build up tolerance. Desensitization allows the allergic antibodies in the patient’s body to cease to function after re-exposure to the allergen, and is important for the improvement of allergic diseases such as allergic rhinitis and allergic asthma. Although the technology of desensitization is more mature in the medical field, there are people who are not suitable for desensitization. If patients have serious immune diseases, or tumors, hypertension, coronary heart disease and severe asthma, etc., some adverse reactions may occur after desensitization, such as redness and itching at the injection site, mucous membrane edema, etc. Once discovered, they should seek medical consultation and have the appropriate measures taken by a professional physician.