For uncomplicated constipation, first-line therapy should be dietary manipulation with increased fibre and fluid intake.
The bulk forming laxative ispaghula husk may take several days to act.
Stimulant laxatives such as bisacodyl and senna increase intestinal motility and often cause abdominal cramp. They should be avoided in intestinal obstruction. Stimulant laxatives become less effective with long-term use. Glycerol suppositories act as a rectal stimulant by virtue of the mildly irritant action of glycerol.
If rectum is full on examination or there is difficulty in evacuation, consider glycerol or bisacodyl suppositories. If bulk–forming and stimulant laxatives are unsuitable, consider at least 30ml daily of lactulose; this may take 48 hours to act.
Older Patients – laxatives in chronic use
Managing constipation in older patients can be complex and individual assessment may be required. Lactulose is not recommended for long-term use in the elderly but can be prescribed along with a stimulant laxative as a short-term solution.