The baby changed the second generation of milk powder diarrhea, may be due to the physiological factors such as not adapting, but also may be due to lactose intolerance, acute enteritis and other pathological factors. You can take general treatment, montelukast and other medication. 1. physiological factors: the baby suddenly change milk powder did not pay attention to the transition, there may be diarrhea and other uncomfortable reactions, you can gradually transition, gradually add to ease the symptoms. 2. Lactose intolerance: some babies have lactose intolerance, can also appear diarrhea, nausea, vomiting, abdominal pain and other symptoms. Lactase can be used to treat the symptoms. 3. Acute enteritis: If the baby happens to be infected by viruses or bacteria when changing the second stage of milk powder, diarrhea, nausea, vomiting and other uncomfortable symptoms may occur. Oral montelukast to protect the mucosa of the gastrointestinal tract, at the same time oral probiotics to regulate intestinal flora, if necessary, can use oral rehydration salts to prevent and treat dehydration.