If a 2.5 year old baby does not urinate for a longer period of time, the following are the main causes. First, the symptoms are caused by diarrhea, which causes an increase in the number of bowel movements and a corresponding increase in the amount of water lost in the stool, causing dehydration in children. When children become dehydrated, the amount of urine decreases, or even no urine for a long time, and the skin is often very dry and the eye sockets are sunken. In this case, children should be given oral rehydration salts or even intravenous glucose, sodium chloride, potassium chloride, etc. Secondly, increase the amount of milk feedings in time. Some children do not urinate for a long time because the amount of milk they drink is too little, and if the amount of milk feedings is increased appropriately, urine will be produced naturally.