One and a half year old baby suddenly do not drink milk, may be physiological factors (such as eating distraction, eating too much complementary food, etc.) lead to, but also may be oral infection, indigestion and other pathological factors lead to. 1. Physiological factors: the baby is attracted by external things, it is easy to lead to eat not concentrate, suddenly do not drink milk, or the baby to add too much supplemental food, occupy the space of milk, may lead to this situation. 2. Oral infection: when the baby’s mouth is infected, due to pain resulting in loss of appetite, there will be a sudden failure to drink milk, usually accompanied by salivation, and some babies will have fever. 3. Indigestion: When the child is not fed properly or has a cold, indigestion occurs, causing loss of taste and appetite, and there will be a sudden failure to drink milk. One and a half year old baby suddenly did not drink milk, there may be other reasons, such as acute upper respiratory tract infection, etc., it is recommended to seek medical attention in a timely manner, improve the examination, to clarify the cause of the disease, and cooperate with the doctor’s diagnosis and treatment.