There are several kinds of this laxative. 1, volumetric laxatives: this type of laxative mainly includes car before senna composite particles and sodium carboxymethylcellulose particles, etc., its role is to increase the volume of feces, retain the water in the feces, and can be mildly promote intestinal peristalsis. Volumetric laxatives are suitable for patients with mild and moderate constipation, and the onset of action is about 24 hours after taking the drug.　　2, osmotic laxatives: these laxatives mainly include lactulose, white composite, compound magnesium sulfate bulk. Lactulose is a sugar laxative, when it enters the colon will be broken down into small molecules of organic acid, can play a role in increasing the water in the feces, to prevent the feces from drying too hard. The white compound, compound magnesium sulfate bulk belongs to magnesium salt laxative, its main ingredient is magnesium sulfate, with the effect of increasing the water in the feces and stimulating the contraction of the intestinal wall. Osmotic laxatives are suitable for patients with moderate and severe constipation, but it can only be used for a short period of time, otherwise it will trigger water electrolyte disorders and hypermagnesemia. In addition, for some patients who can not take magnesium salts laxative constipation, can be allowed to take sodium sulfate and other sodium salts laxative, can also play a role in slowing down the diarrhea.　　3, lubricating laxatives: these laxatives mainly include paraffin oil, castor oil, etc., with the role of softening feces. Lubricating laxatives should not be applied for a long time, and care should be taken when taking them to prevent them from being inhaled into the airways and causing respiratory infections.　　4, suppository laxatives: this kind of laxative mainly includes Keselu, glycerin suppository and bisacodyl, etc., its role is to stimulate gastrointestinal reflexes, so as to strengthen intestinal peristalsis, promote defecation. Pessary laxatives are suitable for constipated patients with little bowel movement and difficulty in defecation.　　5, to promote gastrointestinal dynamics drugs: this type of laxative mainly includes cisapride (Prevacid), mosapride (Gastrin), domperidone (morpholine), etc., and its role is characterized by the promotion of intestinal peristalsis, to help patients with constipation to produce the intention of stool. Promote gastrointestinal dynamics drugs for gastrointestinal dynamics of poor constipation patients, especially for diabetes, gastrointestinal diseases caused by functional constipation patients.　　6, proprietary Chinese medicine: this kind of laxative, including hemp pill, six flavors of an elimination capsule, etc., with lubrication of the intestinal wall, increase the water in the feces and mild promotion of intestinal peristalsis, suitable for mild and moderate constipation patients.