Lactulose

Lactulose is a synthetic, non-absorbable sugar used as an osmotic laxative to treat chronic constipation and to reduce blood ammonia levels in hepatic encephalopathy. It works by drawing water into the bowel, softening stool, and reducing ammonia production. It usually takes 8–12 hours to work for constipation, though it can take up to 2 days. Common side effects include abdominal cramping, gas (flatulence), diarrhea, and nausea.