I. Laxatives (1) volumetric laxatives: including psyllium preparations, wheat bran, methyl cellulose, etc.. These substances are not absorbed, and can absorb water, increase the volume of stool and promote intestinal peristalsis. They usually work 12-72 hours after abdominal pain. It should be used with caution for those who need to restrict water intake as it requires more water to be taken at the same time. Volumetric laxatives have limited effect in the treatment of chronic constipation and are suitable for mild constipation. (2) Osmotic laxatives: Polyethylene glycol, a representative of osmotic laxatives, has previously been used as a bowel cleanser, for colon endoscopy, bowel preparation before surgery and imaging. Recently, it has been widely used as a laxative to treat constipation. Its mechanism of action is unique in that it increases local osmotic pressure, increases stool water content by fixing water through the combination of hydrogen bonds and water molecules, softens stool, restores stool volume and weight, induces bowel movements, and thus promotes stool propulsion and elimination, and is effective in both slow-transit and outlet-obstructed constipation. It is a better choice for constipation patients who need long-term medication because it is more in line with colon physiology, safe and well-tolerated, with precise efficacy, wide range of indications and good taste, etc. (3) salt preparations: as a laxative salt preparations including sodium sulfate, magnesium sulfate and magnesium hydroxide, etc.. Among them, magnesium sulfate is more powerful, fast-acting (0.5-0.3 hours), can lead to a large number of watery stool. Salt preparations are hardly absorbed in the intestine and their action is mainly osmotic, but there are other mechanisms besides, such as magnesium salts that stimulate the release of CCK and promote intestinal motility. Due to excessive intake of magnesium salts will lead to hypomagnesemia, so for patients with renal insufficiency should be disabled. (4) stimulating laxatives: such as senna, castor oil, aloe vera and phenolphthalein. Among them, anthraquinone long-term use can destroy the intestinal muscular plexus, and lead to colonic melanosis. Stimulant laxatives are fast-acting and strong, but have potential long-term toxicity and are suitable for temporary, short-term use. (5) Chlorine channel agonists: its representative, Rubiprostone, can open the chlorine channels in the intestinal mucosa and increase the secretion of intestinal fluid, thus softening the stool and increasing spontaneous intestinal motility to play a role in the treatment of constipation. And it can improve other symptoms of constipation such as bloating, abdominal pain and gas. (6) laxative: lubricating mineral oil is not easily absorbed and wrapped in small fecal pieces or emulsify feces and inhibit fecal formation. Second, prokinetic agents are especially suitable for patients with slow colonic transit. Such drugs used in clinical practice are mainly 5-HT4 agonists, but cisapride and tegaserod have been phased out because of cardiovascular adverse effects. The current application of prilucapride can stimulate enhanced colonic contraction and accelerate gastric emptying. It can increase the frequency of bowel movement and reduce the hardness of stool in patients with constipation. It is mainly used to treat various kinds of constipation and post-surgical gastrointestinal peristalsis with sluggish weakness and pseudo-intestinal obstruction. It is safe and reliable, and no serious cardiovascular adverse reactions have been reported. Regulation of intestinal flora In some patients with constipation, their colonic flora can digest more fiber, making the amount of stool decrease. Regulation of intestinal flora can help improve constipation. Commonly used drugs include bifidobacterium triad, lactobacillus tablets, lactase, and rectify intestinal raw material.