Lactulose is a synthetic disaccharide made from galactose and fructose, widely used as an osmotic laxative and as a key therapy in managing hepatic encephalopathy. Although it is not absorbed in the small intestine, it reaches the colon intact, where bacterial fermentation produces organic acids that draw water into the bowel and reduce ammonia levels mechanisms that define both its laxative action and its role in treating liver-related neurotoxicity. Interestingly, lactulose was not originally created as a medicine; it was discovered in 1930 as a by-product formed when milk was heated, but its therapeutic potential wasn’t recognized until the 1950s, when researchers observed its ability to soften stools and later, in the 1960s, its ammonia-lowering effect in patients with liver cirrhosis. Over time, lactulose became a staple in gastroenterology, valued for its safety, efficacy, and versatility, evolving from a simple carbohydrate curiosity to one of the most commonly prescribed agents for chronic constipation and hepatic encephalopathy worldwide.
