This question has two meanings: First, people who do not have a history of allergic diseases want to know if they can avoid developing the disease. This is mainly because some people have relatives with allergic diseases and want to know if they can avoid developing such diseases by some means. Modern medicine believes that the following conditions are necessary for the development of allergic diseases: 1) a person with a sensitive constitution (related to the influence of genetic and long-term environmental factors); 2) exposure to antigens (exogenous proteins) that can cause the body to have a metamorphic reaction. Unfortunately, these two conditions are beyond human control, for example, genetic factors are inherent and do not depend on our will; environmental factors are more complex and variable and beyond human control; antigens (exogenous proteins) are more uncertain, whether a substance becomes an antigen, in addition to the properties of the substance itself, but also closely related to the condition of the human organism itself. For example, some people who have eaten wheat flour for decades are suddenly allergic to wheat flour at some point in time. From this point of view, there is no way to prevent the onset of the disease because current medicine does not accurately predict the individuals who will develop the disease. The second is whether people who have suffered from allergic diseases before can be prevented from developing them again by special means. If the allergen is clearly known, it is entirely possible to prevent an attack by avoiding contact with the substance (i.e., avoiding exposure to the allergen). For example, penicillin is not used in people with penicillin allergy, and this method is only for the clear allergen. Due to the uncertainty of the occurrence of allergic diseases and the limitations of medical development, there is currently no medical method to prevent the recurrence of allergic reactions to new substances in those who are “allergic”. In general, the current means and methods of preventing allergic diseases in humans are very simple and limited.