Allergy to egg yolk in infants is often caused by the fact that the infant’s digestive and immune systems are not yet well developed and the infant’s immunity is low. Certain parents will add egg yolk as a supplement to their infants too early, which will easily cause allergy. If an infant is allergic to egg yolk, it can manifest as skin erythema, itching, red and swollen lips, as well as digestive symptoms such as nausea, vomiting, diarrhea and abdominal distension. In severe cases, laryngeal edema, hoarseness, difficulty in breathing, accompanied by chest tightness, blue lips, and even anaphylactic shock, hypotension and impaired consciousness may occur. Therefore, once an allergic reaction occurs, you must stop eating egg yolk again, drink as much water as possible, and if necessary, you need to go to the hospital for active treatment. Skin allergy can be treated with local application of dermatol ointment and oral administration of second-generation antihistamines, such as cetirizine or loratadine oral solution, under the guidance of a doctor. In severe cases, glucocorticosteroids such as budesonide can be given for nebulized inhalation as prescribed by the doctor, and oxygen can be given if necessary to relieve the infant’s breathing difficulties. In addition, it should be noted that although egg yolk is rich in nutrients, it is not the first choice as a complementary food and should be added after the infant has gradually adapted to other foods, such as rice flour, rice paste and fruit puree.