1. Why desensitization therapy? The four-pronged treatment plan for allergic diseases (anaphylaxis) includes avoidance of allergens (allergens), medication to control airway inflammation and alleviate clinical symptoms, allergen-specific immunotherapy to improve the immune response process in the patient’s body, and patient management education. Allergen-specific immunotherapy is currently the only treatment that can alter the course of an allergic disease. Nowadays, there are many kinds of drugs used for asthma treatment, and inhaled hormone, as the main drug for asthma control, can comprehensively control airway inflammation and has little side effect, but inhaled hormone is only symptomatic treatment for airway inflammation, and it is not possible to completely avoid allergens after stopping inhaled hormone treatment, after repeated exposure to allergens, the inflammation in the airway of the allergic children will be aggravated again. When the inflammatory reaction becomes severe to a certain extent, clinical symptoms will reappear. Therefore, children with allergic asthma should be treated with specific immunotherapy as early as possible after the symptoms are controlled by medication, when the disease is still in the plastic phase, and before irreversible pathological changes occur in the airways, so as to treat the cause of the allergic disease, and to change the course of the allergic disease and to improve the prognosis. Allergen-specific immunotherapy can make asthmatic children reduce the control of medication, reduce the emergence of new allergens allergy, prevent allergic rhinitis into asthma and reduce the severity of asthmatic children’s condition, which can be used as a supplemental treatment in addition to the avoidance of contact with allergens and drug therapy. 2.Mechanism of desensitization therapy? Who is suitable for desensitization therapy? Allergen-specific immunotherapy is used to improve the clinical symptoms of individuals with IgE-mediated allergic diseases by gradually increasing the dose of allergen products given to them in order to improve the clinical symptoms of subsequent exposures to disease-causing allergens. After determining the allergens of patients with allergic diseases, the allergens are made into allergen extracts and formulated into various preparations with different concentrations, and then repeatedly exposed to the patients through repeated injections or other routes of administration, with the dosages ranging from small to large and the concentrations ranging from low to high, and then maintained after the effective dose is reached, so as to increase the patients’ tolerance of the allergens, so that they will no longer develop allergy phenomena or have reduced allergy phenomena when exposed to such allergens again. Allergic phenomena are reduced or eliminated upon re-exposure to the allergen. Children who are clearly allergic to inhalant allergens by skin allergen testing (prick or intradermal testing) and/or serum allergen testing and whose exposure to these allergens causes clinical symptoms are suitable candidates for allergen-specific immunotherapy. Children with moderate or severe allergic rhinitis or mild or moderate persistent asthma with or without allergic rhinitis and patients requiring long-term maintenance with controlled medications. Patients with severe persistent asthma should be treated and their condition improved before starting desensitization therapy, but patients with severe persistent asthma are mostly sensitized to multiple allergens and sometimes desensitization therapy is not effective. The application of specific immunotherapy in pediatric patients is more advantageous than in adults. Children are in the period of growth and development, their immune system is not yet fully developed, is the best time to receive allergen-specific immunotherapy, the recent efficacy and long-term follow-up have shown that children’s efficacy is better than that of adults. 3.How to carry out the treatment? What are the common desensitization methods? How long is the treatment? Before starting the desensitization treatment, the allergic child should be carefully and comprehensively evaluated to find out the main allergens that cause the child’s clinical symptoms, and then desensitize the child with these antigens in order to achieve the expected therapeutic goal. Skin allergen testing and serum specific IgE antibody testing can determine the causative allergens, but most importantly, whether the child’s clinical symptoms are triggered by exposure to such allergens, and the severity and duration of the clinical symptoms should also be taken into account. If the child has a positive allergen test, but the IgE titer is not high enough to determine the causal relationship between symptoms and allergen exposure, or if the child has a transient seasonal pollen allergy that can be controlled by avoiding allergens or by short-term medication, then the advantages and disadvantages of allergen-specific immunotherapy should be considered, and treatment should be initiated cautiously. The method of desensitization therapy is to apply a standardized desensitization vaccine to the patient, starting with a low dose and gradually increasing the dose, and when the optimal maintenance dose is reached, maintenance therapy is carried out, and after a period of time, desensitization is achieved to the extent that the patient will not develop allergic symptoms (e.g., allergic asthma or rhinitis, etc.) even if he/she comes into contact with the allergen. The specific immunotherapy methods commonly used in clinical practice are classified according to the mode of administration: subcutaneous injection and sublingual administration. The desensitization regimen consists of a drug-escalation phase and a drug-maintenance phase. The drug incremental period is when the concentration of the allergenic preparation is gradually increased from low to high to the concentration of the optimal maintenance dose, mostly for 1-2 months (there are also cluster desensitization methods); the drug maintenance period is the period of time during which the concentration of the optimal maintenance dose of the allergenic preparation is maintained at the same level, and the period of time is from 3 to 5 years. Different manufacturers of desensitizing preparations provide specific protocols for their use. Subcutaneous treatments are given by injecting the drug into the deltoid muscle of the patient’s upper arm. Sublingual desensitization therapy is administered by dropping the medication under the tongue, holding it for 1 to 3 minutes and then swallowing it, following the medication’s prescribed schedule, usually choosing to administer the medication at the same time of day (in the morning or at bedtime). Specific immunotherapy should be continued for more than 3 years, and the time of clinical efficacy varies from person to person, with most of them taking effect 3~6 months after treatment. If the effect of desensitization therapy is not obvious after 1 year, the doctor can decide whether to interrupt the treatment according to the patient’s condition. 4.What are the side effects of desensitization therapy? The side effects of desensitization therapy are local and systemic reactions, which increase in frequency when the concentration of desensitizing agent is increased, and decrease in frequency when the treatment is maintained. Local reactions include: subcutaneous desensitization will produce local redness, swelling, itching, pain and hardness of the injection site; sublingual desensitization will produce transient localized oral itching, fatigue, gastrointestinal discomfort, mild diarrhea, localized urticaria and other symptoms. Systemic reactions include exacerbation of allergic symptoms, nasal symptoms, urticaria, asthma attacks and anaphylaxis. 5.How does desensitization work with conventional asthma medications? Children with asthma desensitization therapy, with asthma medication, adjust the medication should follow the doctor’s instructions, according to the actual situation of the child to adjust the medication program. Asthma medications fall into two main categories: long-term control medications and symptom-relieving medications. Long-term asthma control medications are medications used daily for a long period of time to suppress airway inflammation, maintain normal or approximately normal lung function, and prevent or minimize asthma exacerbations, including inhaled glucocorticosteroids, long-acting β2 agonists, leukotriene modulators, sustained-release theophylline, and sodium cromoglycate. Reliever drugs are drugs that work quickly to relieve bronchoconstriction, smooth muscle spasm and the resulting acute symptoms such as cough, wheeze, chest tightness, shortness of breath, etc., and are used as needed during an attack. Commonly used drugs include fast-acting inhaled β2-agonists, inhaled anticholinergic drugs, short-acting theophylline, oral fast-acting β2-agonists, and systemic glucocorticosteroids. In order to stabilize the patient’s condition at the initial stage of desensitization therapy, conventional asthma medications should be applied in combination with desensitization therapy, and the smallest hormone dose of inhaled hormone + long-acting β2-agonist combination and antihistamines can be used, and the smallest hormone dose of nasal spray hormone medication is added to the allergic asthma combined with rhinitis in children; for maintenance therapy, antihistamines and nasal spray hormone can be discontinued at the time of the initial treatment and the inhaled hormone dose can be gradually reduced until discontinued (the amount of inhaled hormone is not used until discontinued). The dosage of inhaled hormones can be gradually reduced until discontinued (or applied concurrently as required by the condition); any asthma medication required should be increased if the patient’s condition changes and asthma symptoms appear during initial and maintenance therapy.