Lactulose syrup drink, in general, 2 to 3 hours to take effect, but there are cases of prolonged or even ineffective starting time. Lactulose is an osmotic laxative, which is not digested in the stomach and reaches the colon directly in its original form, which can improve intestinal ph with the action of colonic flora. through the high osmotic effect, it makes the stool volume increase, thus stimulating the intestinal wall to promote defecation. The drug is mainly used in the treatment of constipation, but also has the effect of restoring the regularity of intestinal peristalsis, and can also be used in the prevention and relief of hepatic encephalopathy. Lactulose reaches the colon area from drinking, the general digestive process time is 2 to 3 hours, so its onset of action is also in 2 to 3 hours; however, depending on the degree of constipation and intestinal peristalsis, there are also cases of 6 to 8 hours of onset of action.