The reason Lactulose is not taken at night is that the drug is a diarrhea-inducing drug, and frequent bowel movements may occur after use, which can interfere with the patient’s rest. Lactulose is a disaccharide with diarrhea-inducing effect, which is commonly used to treat functional constipation, prevent or treat hepatic encephalopathy, in addition to assisting in the treatment of endotoxemia. In the treatment of functional constipation, it is best taken before or after breakfast, while in the treatment or prevention of hepatic encephalopathy it should be taken 3 times a day, that is, once in the morning, once in the evening. It is contraindicated in patients who are allergic to the drug and in patients with galactosemia, acute abdomen, intestinal obstruction, uremia, diabetic ketoacidosis, acute gastrointestinal disorders, etc. It should be used with caution in lactating women. Common adverse reactions to this drug include diarrhea, bloating and nausea. It is recommended to take Lactulose under the guidance of a doctor, not blindly self-medication to avoid adverse effects.