Management of Constipation


This guideline applies to patients who are initiated on laxatives during their hospital stay or to patients who are not responding to their current laxative therapy. Laxatives are contraindicated in patients with intestinal obstruction and if suspected refer to specialist surgical team.

Assessment / monitoring

Identify possible causes:

  • Underlying disease e.g. hypothyroidism, hypercalcaemia.
  • Mechanical obstruction e.g. rectal tumour.
  • Immobility / dehydration e.g. stroke / diabetes mellitus.
  • Drugs, e.g.:
    • Opioids (including co-codamol and dihydrocodeine)
    • Anticholinergics (includes tricyclic antidepressants, oxybutynin)
    • Verapamil
    • Clozapine (can be life threatening, see guidance here)
    • Aluminium containing antacids
    • Iron and calcium containing preparations.


  • Serum U&Es
  • Calcium
  • Thyroxine (T4)
  • Glucose

General management

Rectal examination

  • Hard faeces – prescribe a faecal softener e.g. lactulose (for more laxative choice see tables below).
  • Soft faeces – prescribe a stimulant laxative e.g. senna (for more laxative choice see tables below)
  • Impaction – for enema e.g. sodium citrate micro-enema or phosphate enema (for more laxative choice see tables below)
  • Empty rectum – suspect obstruction and obtain plain abdominal x-ray.

Patient education

  • Increase dietary fibre (bran, fruit, vegetables).
  • Increase mobility.
  • Ensure adequate fluid intake (especially if on bulk forming laxative e.g. ispaghula husk, or high fibre diet).

Drug therapy / treatment options

If constipation occurs in a patient with or at risk of encephalopathy, please refer to Management of decompensated liver disease for appropriate laxative regimens.

Acute constipation

Constipation of recent onset due to a period of illness or immobility, drug therapy, changes in diet or fluid intake. Laxatives should only be given for short-term use.

Laxative and dose Notes
Senna 15mg-30mg at night Senna liquid preparation also available as 7.5mg/5ml.
Glycerol suppositories, 4g daily Moisten suppositories with water for ease of insertion.

Chronic constipation

Requires long-term management.

Laxative and dose Notes
Ispaghula husk (Fybogel®), 1 sachet twice daily Ensure adequate fluid intake. If ineffective after several days add senna 15mg-30mg at night (short-term only).
Lactulose, 15ml twice daily regularly Use if above option is not effective / appropriate.
+/- Senna, 15mg at night  
Macrogol Oral Powder (Laxido Orange®), 1–3 sachets daily Use if above options are not effective/ appropriate. Ensure adequate fluid intake. Usually effective after 1-3 days when used on its own.
+/- Senna, 15mg at night  

Opioid-induced constipation

Laxative and dose Notes
Senna, 15mg at night -
and either
Lactulose, 15ml twice daily regularly -
Docusate sodium 100–500mg daily -
Co-danthramer suspension 25mg/200mg per 5ml, 5–10ml at night For terminally ill patients only. Titrate dose upwards as necessary.

Rectal impaction

In some cases of rectal impaction, manual evacuation may be required. Seek advice from senior medical staff.

Laxative and dose Notes
Bisacodyl 10mg suppository AND glycerol 4g suppository (1 of each) once daily If these are ineffective after 8-12 hours, administer microenema.
Micralax® (sodium citrate) microenema, 1 at night Time to effect 5-15 minutes
If no result, followed by:
Phosphate enema, 1 in the morning Usually effective after 15-30 minutes; do not use more than twice a day.
Arachis oil retention enema, 1 as a single dose Usually effective after 15-30 minutes; avoid if nut allergy.
If no result, followed 6 - 8 hours later by:
Micralax® (sodium citrate) microenema, 1 as a single dose Time to effect 5-15 minutes.
Phosphate enema, 1 as a single dose  Usually effective after 15-30 minutes.
Macrogol Oral Powder (Laxido Orange®), 8 sachets daily for up to 3 days** For use in resistant cases of impaction. Ensure adequate fluid intake. 
**May not be possible to use this dose in the frail or older people.

Note: Patients unable to swallow, but with a nasogastric or RIG/PEG tube in situ can have certain laxative preparations administered via the tube. Contact ward clinical pharmacist or Medicines Information (see Appendix 6 under hospital site) for details.

In patients with moderate to severe irritable bowel syndrome with constipation who have not responded to, or cannot tolerate all other suitable treatment options, consider linaclotide 290microgram once daily as a one month trial.


Guideline reviewed and content updated June 2021