Clinically used laxatives can generally be divided into five categories: 1, volumetric laxative (swelling), with hydrophilic, absorb water swelling to form a gel, so that the large intestinal volume increases, stimulate the intestinal wall, increase intestinal peristalsis, relieve constipation and the sense of urgency to defecate. Because it is safer, it is often the first choice for treatment. Representative drugs: Ou Che Qian, wheat bran, etc. 2, stimulating laxative, stimulating the intestinal wall, thereby increasing intestinal peristalsis. Representative drugs are anthraquinone within (rhubarb, senna, aloe vera, etc.), phenolphthalein, castor oil, etc. Long-term use can cause colonic melanosis and produce irreversible neurological damage. 3, osmotic laxative, representative drugs: polyethylene glycol electrolyte dispersion, lactulose, etc. 4.Lubricating laxative, mainly lubricates the intestinal wall, so that the feces can be easily discharged. Representative drugs: paraffin oil, open cork, etc. 5.Gastrointestinal motility drugs, representative drugs: Mosapride, Itopride, etc.