West of Scotland Formulary

For uncomplicated constipation, first-line therapy should be dietary manipulation with increased fibre and fluid intake.

Stimulant laxatives must not be used in the presence of faecal impaction in older patients.

Prescribing Notes:

The choice of treatment for constipation depends on the severity of the presentation and other factors including drug history, diet and lifestyle.
It may be appropriate to continue treatment if the precipitator is immobility, drug induced or other continuing factors.
There may be instances where a combination of laxative products is required, and choice should be made based on individual patient requirements.
Bulk-forming laxatives such as ispaghula husk take several days to work and are useful in chronic, simple constipation.
Bulk forming laxatives should be avoided in opioid induced constipation and in patients with faecal impaction.
Osmotic laxatives, such as macrogol compound, are not appropriate for as required use. They make take 48 hours to take effect. Cautious use in patients who have restricted fluid intake.
Macrogol compound is listed in the drug tariff and available generically and is therefore described as such on the formulary.
Stimulant laxatives should only be used if other laxatives (bulk-forming and osmotic) are ineffective. See MHRA Drug Safety Update (August 2020) for more detail.
Stimulant laxatives become less effective with long-term use. Chronic use is not generally appropriate other than for the treatment of opioid induced constipation.
Stimulant laxatives should be avoided in intestinal obstruction and in the elderly in the presence of faecal impaction.
Stimulant laxatives can become less effective with long term use and can cause diarrhoea and hypokalaemia.
Senna has an onset of action of 8-12 hours. It is particularly useful where a rapid effect is required or where stools are soft, but difficult to pass or the patient complains of inadequate emptying. Liquid should be reserved for patients unable to take tablets.
If rectum is full on examination or there is difficulty in evacuation, consider glycerol suppositories.
Glycerol suppositories have a rapid effect (15-30 mins) and can be used for hard or soft stools. They are suitable for acute moderate-to-severe constipation.

History Notes

15/04/2026

Regional formulary chapter launched.

If rectum is full on examination or there is difficulty in evacuation, consider glycerol or bisacodyl suppositories.

Prescribing Notes:

The choice of treatment for constipation depends on the severity of the presentation and other factors including drug history, diet and lifestyle.
It may be appropriate to continue treatment if the precipitator is immobility, drug induced or another continuing factor.
There may be instances where a combination of laxative products is required, and choice should be made based on individual patient requirements.
Osmotic laxatives, such as macrogol compound, are not appropriate for as required use. They make take 48 hours to take effect. Cautious use in patients who have restricted fluid intake.
Macrogol compound is listed in the drug tariff and available generically and is therefore described as such on the formulary.

History Notes

15/04/2026

Regional formulary chapter launched.

Treatment of opioid induced constipation in adult patients who have had an inadequate response to laxative(s).

Treatment of opioid induced constipation in adult patients who have previously been treated with a laxative.

Prescribing Notes:

Patients with opioid induced constipation should initially have their requirement for opioids reviewed and reduced or stopped where appropriate.
When naloxegol therapy is initiated, it is recommended that all currently used maintenance laxative therapy should be halted until the clinical effect of naloxegol is determined.
It may be appropriate to continue treatment if the precipitator is immobility, drug induced or other continuing factors.
Patients should usually have experienced inadequate responses to at least two regular constipation treatments before consideration of either naloxegol or naldemedine.

History Notes

15/04/2026

Regional formulary chapter launched.

Prescribing Notes:

Some patients may require manual dis-impaction.
Enemas may need a district nurse or a carer to administer them.
Rectal enemas are licensed for occasional use only.
In general, enemas should be reserved for pre-operative bowel clearance and for the treatment of impacted faeces if response to oral laxatives or suppositories is insufficient.
Enemas are routinely used in patients with hepatic failure.

History Notes

15/04/2026

Regional formulary chapter launched.

Prescribing Notes:

Linaclotide is accepted for restricted use in patients with moderate to severe irritable bowel syndrome with constipation who have not responded adequately to or cannot tolerate all other suitable treatment options.
Physicians should periodically assess the need for continued treatment. If patients have not experienced improvement in their symptoms after 4 weeks of treatment, the patient should be re-examined and the benefit of continued treatment reconsidered.

History Notes

15/04/2026

Regional formulary chapter launched.

Prescribing Notes:

Refer to the Scottish Palliative Care Guidelines.

History Notes

15/04/2026

Regional formulary chapter launched.

Relieve faecal impaction if present before use of laxatives.

First line options may be used individually. They can also include the combination use of senna or sennosides with either macrogol or lactulose.

Prescribing Notes:

Onset of action of macrogol is 2-3 days. Titrate to a dose which produces 1-2 soft stools per day.
Senna has a rapid onset of action, 8-12 hours. It must not be used in the presence of faecal impaction.
Bulk forming laxatives such as ispaghula husk are not recommended in the treatment of clozapine induced constipation.
Gastrointestinal history and abdominal examination are recommended prior to starting treatment with clozapine. Clozapine should not be initiated until constipation has been managed.
Assess bowel habits at baseline, any point of blood sampling and ideally at every point of contact. Ensure patients and carers are aware of the risks associated with clozapine induced constipation.
Laxative medication should not be stopped suddenly; the rate should be guided by the frequency and consistency of stools.
Stimulant laxatives can become less effective with long term use and can cause diarrhoea and hypokalaemia.
Some antidepressants, antipsychotics and anti-Parkinson’s treatments have strong anticholinergic properties and contribute to constipation, as well as medicines known to cause constipation such as opioids. Prescribing of these medications should be kept under review when used in combination with clozapine and doses reduced/stopped as appropriate.
Macrogol compound is listed in the drug tariff and available generically and is therefore described as such on the formulary.

History Notes

15/04/2026

Regional formulary chapter launched.

History Notes

15/04/2026

Regional formulary chapter launched.

For uncomplicated constipation, first-line therapy should be dietary manipulation with increased fibre and fluid intake.

History Notes

15/04/2026

Regional formulary chapter launched.