The possible reasons for not having a bowel movement after taking montelukast are physiologic, medication, and pathologic factors. The solutions are adjusting diet, stopping treatment, medication and so on. 1. Physiological factors: During the period of taking Montelukast, patients may not have bowel movement due to under-eating or lack of exercise. Patients are advised to adjust their diet, exercise properly, eat regularly and moderately, and eat high dietary fiber food in moderation. 2. Drug factors: no bowel movement may be due to patients overdose or long time taking Montelukast triggered by adverse drug reactions, it is recommended that patients continue to reduce the dose under the guidance of the doctor or discontinue treatment, if necessary, under the guidance of the doctor to take lactulose oral solution and other laxative medication for symptomatic treatment. 3. Pathological factors: patients who do not have bowel movements may also suffer from constipation-type irritable bowel syndrome, intestinal cancer and other diseases, the former can be selected under the guidance of the doctor bifidobacteria, pivoxyl bromide and other medications for treatment, and the latter can be surgical and other treatments under the guidance of the doctor. If the patient’s symptoms can’t be relieved in time, he should consult a doctor in time to avoid serious consequences.