Immunologic mechanisms are involved in the pathogenesis of eczema, and the examination of infants for allergens plays a role in the etiologic diagnosis of eczema and helps in subsequent treatment. The pathogenesis of eczema is unclear and is the result of a combination of multiple internal and external factors. Among them, the external factors include animal fur, plant pollen, fish and shrimp, beef and lamb, peanuts and many other allergens. As a result, allergen examination of eczema patients can help to clarify the cause of the disease, so as to carry out causative treatment to alleviate the symptoms, reduce the recurrence, and improve the quality of life of the patients. In addition, patients with eczema need to undergo routine blood and pathogenetic tests, skin patch test and skin biopsy if necessary.