Lactulose should be taken before meals. Lactulose is a digestive medicine mainly used for the treatment of chronic or habitual constipation, but also for the treatment or prevention of hepatic encephalopathy and coma. Lactulose is mainly used to lower the pH level in the intestinal tract, increase the water in the intestinal tract, increase the volume of stool and increase the peristalsis of the intestinal tract in order to achieve a laxative effect. Lactulose can only exert these effects if it is converted into organic acids by the bacteria in the intestinal tract. Food can significantly reduce the conversion of lactulose by intestinal flora in the intestine, which can seriously affect the therapeutic effect of lactulose. Therefore, it is generally recommended to take lactulose 30 minutes before meals, and you should drink more water during the dosing period.