3-month-old baby diarrhea can be treated with oral intestinal probiotics and montelukast, 3-month-old baby diarrhea is related to intestinal flora imbalance, regulating intestinal flora imbalance, parents can give their babies oral intestinal probiotics. Oral probiotics can improve intestinal resistance, increase the presence of beneficial bacteria in the intestinal tract, promote the recovery of intestinal function, relieve diarrhea, improve the baby’s immunity. Patients with more serious diarrhea should take montelukast as appropriate, montelukast belongs to the common antidiarrheal drugs, which can adsorb viruses and bacteria in the intestinal tract and improve the absorption and secretion function of intestinal cells. The drug ingredients will not be absorbed by the body, will not affect the health of the human body, diarrhea will lead to the loss of water in the body, replenish water to avoid dehydration.