bulk forming agents

Last reviewed 01/2018

Bulk-forming laxative agents include:

  • bran
  • ispaghula husk
  • methylcellulose
  • sterculia granules

Bulk-forming laxatives:

  • have been shown to decrease abdominal pain and improve stool consistency
  • bulk-forming laxatives they are only required if dietary fibre cannot be increased sufficiently - an effective bulk-forming preparation is unprocessed wheat bran (taken with food or fruit juice)
  • not appropriate for acute relief, as they may take several days to work, but they are a good option for long-term control
  • bulk-formng agents increase stool bulk. The increased stool bulk then stimulates peristalsis. Clearly to prevent obstruction, fluid intake must be maintained
  • it is essential to drink adequate amounts of fluid when using bulk-forming laxatives to avoid intestinal obstruction.
  • flatulence and abdominal distension are the most common side effects.

Bulk forming laxatives are contraindicated in patients with existing bowel obstruction or faecal impaction.


  1. MeReC Bulletin 2004 ; 14(6): 21-4.