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Constipation - Management
How can I prevent or manage the adverse effects of laxatives?

  • Most adverse effects can be avoided or reduced by increasing the dose of oral laxatives gradually. Advise people to start at the lowest dose and, if necessary, increase it every few days until one or two soft, formed stools are produced each day. Common adverse effects include:
    • Bulk laxatives: flatulence and bloating.
    • Lactulose: flatulence, cramps, and bloating.
    • Macrogols: bloating, nausea.
    • Stimulant laxatives: abdominal cramps, diarrhoea.
  • Advise people taking bulk laxatives that an adequate fluid intake is important (to prevent intestinal obstruction) and that they should not be taken immediately before going to bed.
  • Advise people taking lactulose or macrogols that an adequate fluid intake is important because the drugs can be dehydrating.
  • The timing of stimulant laxatives can be particularly important for children and the frail or elderly, so that they provoke a single stool each day, at a time when the individual has adequate time to reach the toilet [Clayden et al, 2005]. Usually stimulant laxatives are given at bedtime, to produce a bowel movement the next morning. However, it may take a little experimentation to find the best time for an individual, especially if they naturally tend to defecate later in the day.
  • Avoid excessive doses of laxatives. This leads to diarrhoea and, if prolonged, electrolyte disturbances such as hypokalaemia. Excessive doses of bulk-forming laxatives, or inadequate fluid intake with bulk-forming laxatives, cause intestinal obstruction rather than diarrhoea.
  • If intestinal obstruction is suspected, do not use laxatives.
  • There have been concerns in the past that prolonged use of stimulant laxatives (off-licence use) might reduce colonic function or lead to tolerance. However, there is no convincing evidence that this is the case [Wald, 2006].

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