Lactulose medicine is mainly laxative, then by improving the function of the intestine, laxative, and then reduce the absorption of blood ammonia, which is one of its effects. It is mainly used to treat patients with hepatic encephalopathy of liver cirrhosis. For patients with functional constipation, it can change the stool habit by laxative. It is contraindicated mainly because the sugar content of lactulose oral solution is very high, and lactulose should be contraindicated for diabetic patients, and also for patients who are intolerant to galactose. Lactulose oral solution should not be used together with other drugs during the period of taking lactulose oral solution, appendicitis, intestinal obstruction, and patients with abdominal pain of unknown origin are prohibited to use it.