The common causes of diluted water in a one-year-old baby are indigestion, cold, or due to a viral infection. Treatment is divided into two aspects: first, medication; second, reasonable feeding. In terms of medication, we would recommend oral montelukast to protect the mucosa of the gastrointestinal tract, oral probiotics to regulate the intestinal flora, and oral rehydration salts to replenish the baby’s lost water and prevent and treat the symptoms of dehydration. In terms of feeding, if the baby is formula-fed, we recommend switching to lactose-free formula. If breast-fed, you can continue breast-feeding, adding lactase if necessary, and continue reasonable feeding. The food should be light and relatively easy to digest, do not eat too much sugar and coarse fiber food, such as fruits, vegetables, meat and other foods with high fat content, also temporarily do not eat. After the above treatment, 3-5 days the baby’s condition does not see relief, it is still recommended to go to the hospital.