If the symptoms do not improve after 1 day for acute diarrhea and 2-3 days for chronic diarrhea, you should consult your physician to determine whether you can continue to use this drug. Montelukast is an adsorbent antidiarrheal drug that protects the mucous membrane of the digestive tract. It is usually not recommended for long-term use, as it may cause dry stools and constipation, and may be dependent on the gastrointestinal tract and cause dysbiosis of the intestinal flora. For children, long-term use of montelukast may cause malnutrition because it is difficult to be eliminated from the body and will cover the surface of the intestine for a long time, thus causing the intestine to be unable to effectively absorb other nutrients. In addition, it is recommended to take montelukast between meals, when the gastrointestinal tract is relatively empty and can effectively contact with the gastrointestinal mucosa, so as to reduce the influence of the ingredients in food on the absorption of the drug.