What are laxatives?

Laxatives are foods or drugs that, when ingested, act directly on the gut (or gut contents) to increase stool frequency or ease stool passage. They differ from motility agents such as prucalopride, which exert a promotility effect after systemic absorption. Laxatives are used to treat chronic constipation, usually defined as the presence of difficult or infrequent passage of stool, often accompanied by straining or a sensation of incomplete evacuation, with symptoms present for more than three months.

Chronic constipation is common in the general population. A recent meta-analysis of population based observational studies reported a pooled prevalence of 14% worldwide, with a significantly higher prevalence in women and people of lower socioeconomic status.3 However, symptoms often fluctuate, and recent community data suggest that persistent symptoms over 10 to 20 years affect only 3% of the population.4 Population based studies also show that constipation affects quality of life, is associated with several comorbidities (including haemorrhoids and anal fissure),5 and may be associated with a modest reduction in survival.6

Laxatives may act by several mechanisms, including bulking the stool volume, softening the stool consistency, increasing the stool volume …