Normally constipation will improve in about two weeks after switching milk, because the formulae in different stages of milk powder and different brands of milk powder are different. Babies need to adapt slowly during the switching process, so constipation may occur during the switching process. However, after a period of adaptation, the constipation symptoms will usually improve. Therefore, avoid being too hasty when switching to new milk, and try adding new milk powder to the old milk powder. At the same time with the use of days to add the amount of gradually increased, and finally the new milk powder completely replace the old milk powder. If the baby has constipation before switching to milk, you should consider whether there is indigestion should go to the hospital and try to take intestinal probiotics and other drugs under the guidance of the doctor for treatment, but also let the baby drink more water to replenish sufficient water.