Lactulose is defined by WebMD as a man-made sugar solution used primarily in the treatment of constipation and liver disease. This medication may be taken orally or rectally depending on the condition being treated. Common brand names of lactulose include Enulose and Cephulac.
When taken by mouth for the treatment of constipation, lactulose functions to pull water into the colon, explains MedlinePlus. This water then softens stools and relieves constipation. For treatment of constipation, lactulose is taken by mouth. When lactulose is administered rectally, it is used to relieve symptoms of liver disease. WebMD explains that lactulose is a colonic acidifier, which means it draws ammonia from the blood into the colon so it can then be removed from the body.
WebMD also asserts that lactulose is not a cure for liver disease but instead may be helpful in improving mental status. Additionally, when it is used to treat constipation, lactulose may take up to 24 hours to work, reports MedlinePlus. Common side effects of the medication include diarrhea, gas and nausea. MedlinePlus cautions users to immediately stop taking the medication if vomiting or stomach pain develops. In these cases, it is recommended for patients to immediately contact their doctor.