A substance that promotes bowel movements, used to relieve constipation. Laxatives work through several mechanisms: bulk-forming types such as ispaghula absorb water and add stool bulk; osmotic types like lactulose draw water into the bowel; stimulant types such as senna trigger intestinal contractions; and stool softeners ease passage. While effective short-term, habitual use can disturb fluid and electrolyte balance and make the bowel dependent. Dietary management of constipation should come first: adequate fibre, fluids, and physical activity. Certain foods, including prunes and kiwifruit, have natural laxative effects. Also called purgatives, these medicines should be used as directed and not as weight-loss aids.