how long does it take for lactulose to work

Lactulose generally takes about 24 to 48 hours to start working. It softens the stool by drawing water into the bowel to make passing stool easier. If constipation persists after 3 to 5 days of use, it is advised to consult a doctor. Lactulose is an osmotic laxative and is slower acting compared to some other types of laxatives which may work within hours, but lactulose typically needs a couple of days to have an effect.