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Bulk-Forming Laxative

Ispaghula Husk

Brand names: Fybogel, Metamucil, Regulan

Ispaghula husk (psyllium) is a bulk-forming laxative used in the management of constipation and to maintain regular bowel function, including in conditions where a softer, bulkier stool is helpful.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

Its soluble fibre absorbs water in the gut to increase faecal mass, which stimulates peristalsis and softens the stool.

Prescribing in practice

  • Take with plenty of fluid and avoid taking immediately before going to bed, as inadequate fluid intake risks intestinal or oesophageal obstruction and impaction.
  • It is contraindicated in intestinal obstruction, faecal impaction and conditions such as colonic atony where bulking agents are inappropriate.
  • Full effect develops gradually over days, so it is not suitable for rapid relief of acute constipation.

Monitoring

Routine laboratory monitoring is not required; review the bowel response and ensure adequate fluid intake is maintained.

Counselling the patient

  • Mix the dose with plenty of water and drink it straight away, and keep your fluid intake up during the day.
  • Do not take it just before lying down or going to bed.

Evidence & guidelines

Bulk-forming laxatives such as ispaghula are recommended as a first-line option for constipation in line with NICE guidance.

Reference: NICE CG61 Irritable Bowel Syndrome; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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