The fastest-acting laxatives mainly include stimulant laxatives and volumetric laxatives. Stimulant laxatives include bisacodyl, senna, rhubarb, castor oil, etc., the intestinal wall has a strong stimulating effect, causing extensive peristalsis of the colon, and produce reflex defecation. Volumetric laxatives magnesium sulfate, sodium sulfate, etc., volumetric laxatives orally absorbed less, so that the osmotic pressure in the intestines, so that the intestinal water increases, stimulate intestinal peristalsis and produce diarrhea. In addition, there are osmotic laxatives such as lactulose, osmotic laxatives can make water, electrolytes retained in the intestinal lumen and produce hypertonic effect, no intestinal irritation, the role of relatively weak. Lubricating laxatives such as glycerin and corkscrew have a mild stimulating effect on the rectum. Swelling laxatives polyethylene glycol 4000, carboxymethyl cellulose, wheat cellulose, etc., promote defecation by increasing water in the intestines, promoting peristalsis, softening feces, or lubricating the intestines, and have a gentle action. Different types of laxatives have different applicability, and different types of laxatives should be selected clinically according to different situations. It is recommended to use the medication under the guidance of a physician.