The problem of diarrhea in 4-month-old babies usually has the following reasons: firstly, it may be caused by indigestion, secondly, it may be caused by a cold abdomen, and it may be caused by dietary contamination, as well as allergy to milk proteins and lactose intolerance, etc., so it is necessary to target improvement. If the diarrhea is accompanied by sour stools, a large number of milk petals, poor appetite, nausea and even vomiting, consider and indigestion related, parents should pay attention to the child’s daily amount of milk and the type of milk or milk powder is suitable for the child, and make timely adjustments, from the root of the child’s diarrhea problem. If the diarrhea is caused by cold, then in daily life, parents should pay attention to the child in time to increase or decrease the clothing, do a good job of abdominal warmth, when the diarrhea is more serious, but also in the guidance of the doctor to the baby to choose the appropriate medication for treatment. It may also be because the baby to eat milk bottle mouth or milk appeared to be contaminated, caused by bacterial enteritis diarrhea, or sense of the virus will also cause diarrhea. These cases need to do routine stool examination, and then according to the situation by the clinician for diagnosis, and then carry out the appropriate anti-infection treatment. There is also a possibility of allergic diarrhea, that is, the baby is allergic to milk proteins or even breast milk proteins. In this case, it is necessary to switch to deeply hydrolyzed milk powder or amino acid milk powder. There are also babies with lactase deficiency. You can take anti-diarrhea milk powder or lactase supplementation to get relief. There are many reasons for baby diarrhea, if the baby diarrhea during this period is more serious or lasts for a longer period of time, you need to go to the regular hospital for medical treatment in a timely manner to carry out the appropriate examination, and actively treat diarrhea, so as not to cause dehydration machine electrolyte disorders, miss the best time for treatment.