(Disclaimer: This article is for scientific purposes only. In order to protect the patient’s privacy, the relevant information in the following content has been processed) Abstract: Milk and egg allergy is a common cause of blood in stools in infants and young children, and it is important to rule out the possibility of allergy when encountering infants with blood in stools in the clinical setting. This case is a 1-year-old male infant, breastfed, who presented to the clinic after finding blood in the stool, and was treated with anti-infective and probiotic supplementation in an outside hospital, with no relief after half a month. After examination at our hospital, it was found that the blood in the stool was related to milk and egg allergy, and the mother was advised to avoid the related food, and the stool gradually returned to normal. Basic information] Male, 1 year old [Type of disease] Blood in stool, milk and egg allergy, allergic proctocolitis [Hospital] Zhongnan Hospital of Wuhan University [Date of consultation] May 2022 [Treatment plan] Allergen test, allergen avoidance, breastfeeding [Treatment cycle] Fasting from related foods for 2 days, allergen review after half a year [Treatment effect] Gradual relief of the blood in the stools of the child. A mother with a 1-year-old child and a diaper stained with yellow stool came to the clinic, complaining that her child had blood in stool repeatedly for half a month, and that the frequency of stools had increased in the early stage of the disease. The mother looked anxious, carefully asked about past history: breastfeeding, no rash, no fever, no obvious abdominal pain and crying. Complementary food added apple, banana, egg, rice paste. Previous out-of-hospital stool routine plus occult blood suggests: leukocytes, erythrocytes, positive occult blood, visible blood on the urine, allergic proctocolitis. We performed skin prick and serum atopic IgE tests on the child, and the results showed positive results for egg and milk, which are currently diagnostic of sensitization. However, since the primary mechanism of allergic rectocolitis may be non-IgE mediated or mixed mechanism mediated, and whether the sIgE and skin prick test positivity of milk and egg have a definite relationship with blood stools is still only inferred, the next step was to have the mother and the child to abstain from the above mentioned foods at the same time and to continue to maintain breastfeeding without adding new complementary foods. The blood in the stools decreased after 2 days of fasting and after 4 days there was no blood in the stools, but the occult blood was positive. This basically inferred that the child’s bloody stools were related to cow’s milk and egg allergy. To further confirm the diagnosis, it is necessary to do a food provocation test, that is, to add eggs or milk to the child’s food step by step, and observe whether the bloody stools reappear, because the food provocation test is the gold standard for the diagnosis of food allergy, and after the food provocation test, the child’s allergy to eggs and milk can be clarified. After the food excitation test, the child’s allergy to egg and milk was clarified. After the child’s allergy was clarified and the food was avoided, the phenomenon of blood in the stool gradually decreased and disappeared, so as a doctor, I was really happy for the child and his parents. As a doctor, I am really happy for the child and his parents. After six months of abstaining from eggs and milk, the child’s mother said that the phenomenon of blood in the stools had not appeared again, and the follow-up test showed that the positive occult blood had disappeared. Parents should note that milk and egg are common allergens in food allergy in infants and young children, but the good thing is that most of these two types of food will be tolerated as the child grows up. Therefore, it is recommended that the child undergoes allergen review every six months, and may undergo food provocation test, so that the child can consume the relevant food again when milk and egg tolerance occurs. In addition, when adding complementary foods in the future, attention should be paid to the slow addition of small dosages in gradual increments, and a good food diary should be kept. The common causes of bloody stools in infants include gastrointestinal infection, food allergy, intussusception, anal fissure caused by constipation, taking iron products, etc. Parents should not be overly anxious when such a situation occurs, but should go to a professional hospital in a timely manner to clarify the specific cause of the problem and then take appropriate treatment. In the case of this patient, after the diagnosis was confirmed to be caused by food allergy, avoiding this kind of medication in accordance with the doctor’s advice can effectively prevent recurrence.