Montelukast is a very common clinical antidiarrheal drug with good antidiarrheal effect. The principle is mainly twofold: 1) etiological treatment, targeting the pathogens; 2) symptomatic treatment, targeting the intestinal mucosa. Etiologically, mainly montelukast can make pathogens, such as bacteria, viruses and the toxins and gases they produce, lose their pathogenicity and remove the causative factors from the etiology, so as to achieve the purpose of anti-diarrhea. And for the symptom, mainly montelukast can cover the intestinal mucosa and form a barrier in the intestinal mucosa, this barrier can both promote the repair of the mucosa and enhance its defensive properties, thus achieving the purpose of stopping diarrhea.