The number of patients with chronic constipation is on the rise, but the pathophysiological mechanism of chronic constipation is very complex, so there is no specific treatment, and laxatives are the most commonly used in pharmacological treatment. So how to choose laxatives? What types of laxatives are there? 1, volumetric laxatives: after absorbing water in the intestine, it can increase the volume of stool, and after being decomposed by bacteria in the colon, it can increase the intestinal osmotic pressure, prevent the absorption of water in the intestine, enhance the effect of laxative, and improve the symptoms of chronic constipation. 2, lubricating laxatives, including liquid paraffin, glycerin, can soften the stool, but long-term use of liquid paraffin may inadvertently attract aspiration pneumonia when swallowing pauses in the esophagus, and can also lead to perianal leakage and anorectal mucosal rupture, resulting in foreign body reaction. 3. Osmotic laxatives contain molecular substances that are not easily absorbed by the intestine, forming a hypertonic environment in the intestine, which can absorb large amounts of water and increase the volume in the intestine to promote defecation. 4.Stimulating laxatives include senna, diacetin and so on. The mechanism of action is to stimulate the sensory nerve endings in the colonic mucosa to increase intestinal peristalsis, and to inhibit water absorption in the intestine by affecting the transport of water and electrolytes in the intestinal epithelium, thus promoting defecation. Considering the current clinical evidence and the characteristics and side effects of the drugs, volumetric laxatives, lubricating laxatives and stimulating laxatives can be used for the treatment of intermittent constipation, while osmotic laxatives are more suitable for the long-term treatment of chronic constipation.