In the treatment of chronic constipation[2], the metabolites of lactulose draw water into the bowel, causing a cathartic effect through osmotic action. Unlike other laxatives that are recommended for temporary relief, lactulose can be taken daily for decades. [1] It is safe for people of all ages, except for those in a very small percentage of the population that are galactose intolerant. Dosage may have to be adjusted over time to produce the desired effect.