Managing constipation in IBS

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Dr. Jane Varney - Research Dietitian, 23 July 2018

Constipation is a common problem in IBS, and thought to affect over half of all patients(1). 

Common signs and symptoms of constipation include:

  • Difficulty passing a bowel motion (straining)
  • A feeling of incomplete evacuation 
  • Hard or lumpy stools
  • Infrequent bowel motions (usually less than 3 bowel movements per week) 
  • Feeling of blockage in the anus and/or rectum
  • Having to use fingers to remove stool during a bowel movement (digital evacuation) (2)

If you suffer constipation, this may exacerbate other IBS symptoms, such as abdominal pain, excessive wind (or gas), bloating and/or distension. 

  • A number of factors may contribute to constipation in IBS(3). These include:
  • Slow movement of contents through the intestine (sometimes called delayed transit)
  • Heightened sensitivity to pain (sometimes called visceral hypersensitivity)
  • Problems with intestinal secretion (not enough fluid being released into the intestine)
  • Problems with pelvic floor muscles during defecation (sometimes called dyssynergic defecation), 
  • Problems with the rectum during defecation (sometimes called inadequate rectal propulsion)

Other factors that may contribute to constipation include:

  • Some medications (e.g. codeine for pain relief)(4)
  • Some nutritional supplements (e.g. iron supplements)(4)
  • Diet (particularly an inadequate fibre intake)
  • Dehydration(5)
  • Physical inactivity(6)

Treatments that may improve constipation in IBS include:

  • Increasing dietary fibre intake (choose low FODMAP, high fibre foods if following a low FODMAP diet)
  • Fibre supplementation (try fibre supplements such as linseeds, oats, oat or rice bran, methylcellulose, sterculia and/or psyllium). Wheat bran should be avoided as it may worsen pain and bloating.
  • Ensuring adequate, but not excessive fluid intake - additional fluid intake (above normal levels) does not appear to increase in stool output in healthy individuals
  • Low FODMAP diet (may reduce pain and bloating associated with constipation, and some studies have shown improvements in constipation per se)
  • Including caffeinated beverages 
  • Regular exercise 
  • Laxatives (e.g. polyethylene glycol) - speak to your doctor for advice 
  • Prescription medications (e.g. lubiprostone, linaclotide, prucalopride, selective serotonin re-uptake inhibitors) - speak to your doctor for advice 


  1. Hungin AP, Whorwell PJ, Tack J, Mearin F. The prevalence, patterns and impact of irritable bowel syndrome: an international survey of 40,000 subjects. Alimentary pharmacology & therapeutics. 2003;17(5):643-50.
  2. Ford AC, Moayyedi P, Lacy BE, Lembo AJ, Saito YA, Schiller LR, et al. American college of gastroenterology monograph on the management of irritable bowel syndrome and chronic idiopathic constipation. The American journal of gastroenterology. 2014;109 Suppl 1:S2-S26.
  3. Siah KTH, Wong RK, Whitehead WE. Chronic Constipation and Constipation-Predominant IBS: Separate and Distinct Disorders or a Spectrum of Disease? Gastroenterology & hepatology. 2016;12(3):171-8.
  4. Chey WD, Kurlander J, Eswaran S. Irritable bowel syndrome: a clinical review. Jama. 2015;313(9):949-58.
  5. Klauser AG, Beck A, Schindlbeck NE, Muller-Lissner SA. Low fluid intake lowers stool output in healthy male volunteers. Z Gastroenterol. 1990;28(11):606-9.
  6. Lacy BE, Mearin F, Chang L, Chey WD, Lembo AJ, Simren M, et al. Bowel Disorders. Gastroenterology.150(6):1393-407.e5.

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