Allergic diseases have a natural progression (atopic march) in which characteristic allergic clinical manifestations appear successively at a particular age and persist for many years, and as they age, certain symptoms may predominate while others diminish or disappear altogether, usually with atopic dermatitis (eczema) and food allergy in children being the first symptoms, gradually progressing to allergic rhinitis and eventually leading to asthma. Atopic dermatitis (eczema), allergic rhinitis and asthma are common diseases, especially in Western countries, and their incidence has been increasing in recent decades. Eczema is a chronic recurrent infectious skin disease with pruritus, mossiness, and scarring, and is the most common infectious skin disease of childhood, usually starting within the first year of life. The prevalence of eczema is 10%-20% in children and 1%-3% in adults worldwide, 17.2% in children aged 5-9 years, and 0.3%-20.5% in children aged 13-14 years, with a trend of increasing prevalence in upper classes and people living in urban areas, especially in developed industrialized countries. 35%-40% of children have food allergies and atopic dermatitis occurring at the same time. The incidence of food allergy in children generally peaks at 2 years of age, is 6-8% at 1 year of age, and decreases to 1-2% in adulthood. In recent years, numerous studies have confirmed the natural course of allergic diseases, whereby atopic dermatitis and food allergy are the first manifestations in childhood and can persist for many years, progressing to allergic rhinitis and asthma. A study of 2222 infants aged 11.5-22.5 months with eczema found that 64% of those with eczema manifesting within 3 months of birth were sensitive to IgE-mediated egg or milk or peanut, and that the proportion of such sensitivity increased with the severity of eczema in infants up to 12 months of age, and that this phenomenon did not manifest itself in children with eczema after one year of age. . By the time they reach adulthood, even fewer of those with eczema have food allergies. There is also a lot of research on the relationship between eczema and allergic rhinitis and asthma. It is well documented that more than half of children with severe atopic dermatitis eventually develop asthma, and about 75% develop allergic rhinitis. The presence of eczema in children before the age of 2 years, especially within 6 months of birth, is a high risk factor for the development of allergic rhinitis and or asthma by the age of 6-7 years, more significantly in boys, with rates as high as 45%. Recently, the impact of eczema on the persistence of childhood asthma into middle age was first suggested in a retrospective study, where eczema in children was significantly associated with new-onset asthma in three different life periods: preadolescence, adolescence, and adulthood, and persistent asthma from 8 to 44 years of age. A number of studies have also shown a strong correlation between childhood allergic rhinitis and the subsequent onset of asthma. Between 10% and 40% of patients with allergic rhinitis also have asthma, and up to 80% of patients with asthma also have allergic rhinitis. All the above studies confirm the natural course of allergic diseases and shed good light on their interrelationships. Focusing on prevention for an individual child genetically identified as susceptible to allergic disease is what may fundamentally alter the natural course of allergic disease. (i) Food prevention In 2001, WHO advocated the continuation of single breastfeeding for more than 6 months because the premature addition of complementary foods (exogenous protein antigens) is detrimental to the conversion of the immune system from Th2 to Th1 in early infants lacking Treg cells, leading to the development of Th2-dominant allergic reactions. In the last two years, a large number of new studies have disproved the previous theories and concluded that exclusive breastfeeding with delayed (>6 months) complementary food intake not only does not reduce the development of allergic diseases, but rather increases their incidence, while being detrimental to the health of the infant. Jews living in Israel have a much lower rate of allergy to peanuts than Jews immigrating to the United Kingdom because the former consume more peanuts in early childhood, suggesting that oral exposure to food allergens may play an important role in inducing tolerance to food allergens. It has been suggested that delayed supplemental food intake damages the organism and increases allergen sensitization due to missing the optimal period (4-6 months) for critical and effective transoral induction of immune tolerance in infants. It is well documented that a high intake of fruits, vegetables, legumes, seafood and whole grains and a low consumption of trans fatty acids and simple sugars during maternal pregnancy and childhood can effectively reduce the risk of developing allergic diseases. (ii) Environmental prevention The environment has an important influence on the development of allergic diseases. Among them, smoke from smoking is an important cause of asthma and other allergic diseases. Some studies have shown that smoke in the environment from smoking can increase the risk of allergic sensitization and development of asthma in children. Therefore, it is highly recommended that all parents quit smoking. Dust mites are a common allergen in the environment and it was first suggested through research studies that strict avoidance of dust mites and highly antigenic foods could reduce allergen sensitization in infants in the high-risk group. As with the hygiene hypothesis, exposure to microorganisms during childhood reduces the chances of developing allergic diseases, but it should also be noted that respiratory viral infections are a high risk factor for developing asthma. (iii) Internal medicine treatment In recent years, there have been rapid advances in specific immunotherapy, which can effectively reduce the symptoms of allergic diseases and decrease the risk of developing asthma. The possible mechanisms are to induce the formation of regulatory T cells and to block the formation of specific antibodies. There is information that food desensitization therapy in children is effective. Desensitization of children with milk allergy by oral administration of increasing doses of milk can significantly increase milk tolerance with no change in body IgE levels and a significant increase in IgG4 levels. It is important to note that the goal of oral immunotherapy is not complete tolerance to the previously allergic food, but rather to increase the tolerated dose and reduce or avoid serious adverse reactions. A variety of probiotics are believed to have a positive effect on maintaining intestinal flora balance, maintaining the intestinal microenvironment and restoring normal intestinal permeability, while probiotics may also enhance the immune barrier function of the intestine and reduce the formation of proinflammatory factors, thus preventing the development of allergic inflammation. A recent study found that pregnant women and infants less than 2 years old who took lactobacilli had a 50% lower risk of developing eczema at age 2, suggesting a preventive effect on eczema. Further research is needed to confirm the effect of probiotics on asthma. Several other pharmaceutical agents, including antihistamines, corticosteroids, and calcineurin inhibitors, have also been used to block the natural course of allergic diseases. One study showed no change in the prevalence of developing asthma in infants after 18 months of cetirizine application, but reduced the risk of developing asthma in infants allergic to house dust mites and or pollen. Calcium neurotrophin inhibitors treat eczema by inhibiting transcription of Th1 and Th2 class cytokines and blocking T cells activated by aureus superantigens. Future large sample, multicenter, case-control studies are needed to clarify the safety of the above drug agents and their effectiveness in intervening in the natural course of allergic diseases such as asthma.