Laksatives

Laksatives, more commonly spelled laxatives, are substances that facilitate bowel movements by increasing stool water content, stool bulk, or intestinal motility. They are used to treat constipation, to prepare the bowel before medical procedures, and to relieve certain functional bowel disorders.

Laxatives are classified by mechanism. Bulk-forming laxatives (psyllium, methylcellulose, calcium polycarbophil) absorb water to produce softer, larger stools. Osmotic laxatives (polyethylene glycol, lactulose, sorbitol, magnesium hydroxide or citrate) draw water into the intestine. Stimulant laxatives (senna, bisacodyl) stimulate intestinal peristalsis. Stool softeners or emollients (docusate) help mix fat and water into the stool. Saline laxatives, a subset of osmotic agents, include magnesium or phosphate salts. Newer prescription agents such as lubiprostone and guanylate cyclase-C stimulators (linaclotide, plecanatide) are used for chronic constipation and IBS with constipation.

Indications and use: often used for short-term relief of constipation; polyethylene glycol-electrolyte solutions are used for bowel cleansing before colonoscopy or surgery. Dosing and duration depend on the product and patient factors such as age and kidney function. In pregnancy, certain laxatives are preferred; bulk-forming products are generally considered safe when used as directed.

Safety considerations: do not use laxatives in the presence of known or suspected bowel obstruction, severe abdominal pain, or inflammatory bowel disease without medical advice. Long-term or excessive use may cause electrolyte disturbances, dehydration, and, for stimulant laxatives, dependence or damage to the colon. Laxatives can interact with other medications by changing their absorption; take with ample water and separate from other meds if advised.