How effective is the antidiarrheal drug montelukast? In fact, the drug montelukast is quite effective in stopping diarrhea, but in the process of taking this drug, what you must pay attention to is the method of taking it, and you must make sure to take it on an empty stomach. If the diarrhea is strong, 10-20 times a day, you should increase the dose of the drug, you can eat two packs once, three times a day. Montelukast is a relatively safe drug and can be used for pregnant and lactating patients, but montelukast is only used for symptomatic treatment of diarrhea and the cause of diarrhea must be analyzed. If the diarrhea is caused by an infection, antibiotic anti-infection treatment must be administered. If it is an immune-related disease, hormones must also be taken if necessary.