In the consultations, it was found that perhaps the differences arising from the doctors’ understanding led to the improper choice of the main measure of anti-allergy treatment – avoidance of food allergens – and the efficacy was always unsatisfactory. Take milk protein allergy as an example (not including differences in hydrolyzed components). Based on the grading of allergy (mild, moderate and severe), it is common to use partially hydrolyzed milk powder for mild allergy, deeply hydrolyzed milk powder for moderate allergy and fully hydrolyzed milk powder for severe allergy, and then to recover step by step after a period of time, i.e. to transition from high hydrolysis to low hydrolysis to regular milk powder. In fact, this approach is illogical, because the patient or never out of a certain intensity (well beyond the desensitization dose level) of antigenic stimulation, i.e. harmful stimulation persists. According to the relationship between oral immune tolerance mechanisms, the core of mucosal immunity, and allergy, the restoration of mucosal immune function is the most important physiological basis for the elimination of allergy. Once an allergy occurs, it indicates the formation of structural and functional damage to the mucosal immune system (whether mild or severe allergy), and it takes at least 12 weeks to 24 weeks (3 to 6 months) to return it to normal from the antigenic stimulus. According to the principle of “desensitization” (similar to “homeopathy”), the principle of proper use of hydrolyzed milk powder is: regardless of the degree of allergy, it is best to start with a completely hydrolyzed milk powder without antigenic properties (amino acid milk powder) for at least 3 to 6 months, until the food-specific antibodies (commonly known as allergens) IgE and IgG are gone (negative), then gradually transition from high to low hydrolyzed milk powder to regular milk powder. We would like to remind that the presence of food-specific antibodies IgG (not simply in the sense of allergens) cannot be ignored, it is one of the important parameters of the abnormal immune basis of the mucosa. Other foods, sometimes, are difficult to avoid completely. For example, eggs are often implicit in other foods (e.g. children’s sausages) or during processing (it is almost impossible to avoid eggs in the kitchen, including used oils and kitchenware; shared production lines, see Oreo cookies instructions), or even in the air (cooking fumes such as fried eggs) and chicken products (broilers are contaminated with broken raw egg during slaughter), etc. Therefore, in the process of avoiding food to the maximum extent possible (which is still very difficult to avoid 100%) the patient is already in a state of “desensitization” measures. It is important to remember that the theoretical time to complete avoidance is the time needed for mucosal immune function to repair, regardless of the substance to which one is allergic.