Vitamin AD includes pills, soft capsules, drops and other dosage forms. Diarrhea in infants who take vitamin AD may be related to drug allergy, drug overdose, or with colds. 1. Drug allergy: If infants are allergic to vitamin AD preparations, intestinal reactions may occur after eating, manifested as diarrhea, which may also be accompanied by systemic symptoms such as skin rash and fever. 2. Drug overdose: infants to vitamin D sensitivity to individual differences, some infants are very sensitive to small doses of vitamin D, can cause gastrointestinal adverse reactions, such as diarrhea and abdominal pain. 3. Colds: If infants take vitamin AD preparations during the period, did not pay attention to abdominal warmth, colds can cause gastrointestinal dysfunction, diarrhea and other symptoms. There are other causes of diarrhea in infants taking AD, it is recommended to consult a doctor in time, follow the doctor’s instructions for further examination, with the help of the doctor to clarify the cause, and targeted treatment or treatment.