Lactulose can promote gastrointestinal peristalsis, laxative effect is strong, in the evening to take may be night defecation, affecting the quality of sleep, so it is not recommended to take at night. Lactulose is an osmotic laxative, in the intestinal tract decomposition into lactose and fructose not absorbed by the intestinal tract, increase the osmotic pressure in the intestinal tract, so that the intestinal tract increased water, but also can stimulate intestinal peristalsis, promote defecation, commonly used in the treatment of chronic or habitual constipation, sensory encephalopathy, and so on. Lactulose has a significant laxative effect and may interfere with sleep if taken at night. Adverse reactions that may occur when taking the drug include abdominal pain, diarrhea, nausea and vomiting. It is contraindicated in people who are allergic to lactulose. The drug is used in higher doses for the treatment of hepatic coma or precoma and should be used with caution in diabetic patients. Pregnant and lactating women should use it with caution. Elderly people may develop electrolyte disorders if used for a long period of time, and the dose of the drug should be adjusted by a doctor as needed. The dose and time of Lactulose should be adjusted according to the condition under the guidance of the doctor.