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1.6 Laxatives

See Prescribing Notes below for factors to consider regarding laxative choice

1st choiceIspaghula husk (Fybogel® sachets)
2nd choice

Macrogol compound oral powder sachets

3rd choiceOral Senna tablets 7.5mg, syrup 7.5mg/5ml
Faecal loading / Impaction of rectum
1st choiceMacrogol compound oral powder sachets
2nd choiceGlycerol (glycerin) suppositories 4g
Bisacodyl suppositories 10mg
Sodium citrate enema (Micralax® micro-enema)
3rd choicePhosphate enema (Fleet® Ready-to-use Enema)

Prescribing Notes

  • For further details on the management of constipation see CKS.
  • See NICE CG 61 for the management of irritable bowel syndrome.
  • Palliative care patients should be managed differently – refer to the Palliative Care section.
  • For uncomplicated constipation, first-line therapy should be dietary modification with increased fibre and fluid intake. Constipating medication should be adjusted.
  • Oral laxatives should be offered if dietary measures are ineffective, or while waiting for them to take effect:
    • initial treatment for most people should be with a bulk forming laxative (ispaghula husk)
    • if stools remain hard, an osmotic laxative should be added or switched to
    • if stools are soft but the person still finds them difficult to pass or complains of inadequate emptying, a stimulant laxative should be added
  • Ispaghula husk may take several days to act.
  • Bulk-forming laxatives, e.g. ispaghula husk, should always be swallowed with plenty of water to avoid intestinal obstruction. They should not be taken immediately before going to bed.
  • As bulk-forming laxatives require good fluid intake consider that this may be difficult for the frail or elderly.
  • Bulk-forming laxatives are not recommended in opioid-induced constipation.
  • If bulk forming macrogol and stimulant laxatives are unsuitable, consider at least 30ml daily of lactulose; this may take 48 hours to act. Lactulose should not be prescribed on an ‘as required’ basis.
  • Lactulose is not recommended for patients with irritable bowel syndrome – constipation predominant (IBS-C) as it can exacerbate symptoms such as bloating.
  • The use of phosphate enemas should be discouraged, especially in frail elderly patients and in those with renal impairment.
  • For people with IBS-C, see also section 1.2.
  • A number of other treatments for constipation have been accepted for use in Northern Ireland. These are not first line treatments and should only be prescribed in the particular circumstances outlined. See the managed entry page for information on our decision regarding lubiprostone and naloxegol and NICE for further information on prucalopride.
  • In chronic constipation referral should be arranged if red flags are present, treatment is unsuccessful, or if there is faecal incontinence.


  • Avoid using two laxatives of the same class together (e.g. lactulose and macrogol) – as this increases the risk of side effects.
  • Lactulose is not recommended for long-term use in older patients due to the potential for fluid and electrolyte imbalance.
  • Patients with cardiovascular impairment should not take more than 2 sachets of oral macrogol powder compound in any 1 hour.
  • Phosphate enemas should be administered with caution to patients with renal impairment (discourage use in frail elderly and in renal impairment).
  • In refractory constipation other causes should be considered, e.g. obstruction of bowel.