Habitual diarrhea after breakfast is more often than not abnormal and is considered to be caused by irritable bowel syndrome. The etiology of irritable bowel syndrome is unclear and may be due to factors such as visceral hypersensitivity, intestinal microecological imbalance, and abnormal gastrointestinal dynamics. Patients may experience persistent or intermittent diarrhea, abdominal pain, constipation, etc. Some patients with irritable bowel syndrome may experience habitual diarrhea after morning, which is an abnormal manifestation. Irritable bowel syndrome can be used under the guidance of a doctor, such as montelukast, loperamide and other antidiarrheal drugs, as well as scopolamine, scopolamine and other antispasmodic drugs. In addition, patients usually need to develop regular eating habits, eat less fried chicken, panko and other greasy food. Habitual diarrhea after breakfast is not a normal phenomenon, it is recommended that patients seek medical attention in a timely manner, under the guidance of a doctor to clarify the cause of the disease, and follow the doctor’s instructions for treatment.