Constipation in adults


Functional gastrointestinal disorders (FGIDs) are diagnosed and classified using the Rome criteria for symptoms over the preceding three months. This guideline refers to functional constipation, which can feature:

  • Normal transit constipation - stool movements are normal through the colon
  • Slow transit constipation - stool movements are slower though the colon
  • Defaecation disorders - rectal emptying difficulty

Functional (primary or idiopathic) constipation is chronic constipation without a known cause. Secondary (organic) constipation can be caused by a drug or underlying medical condition. Please see the link to the NICE guidance at the bottom of the page for a full list of secondary causes of constipation.


Functional Constipation diagnostic criteria*

Must include two or more of the following:


1. Straining during more than ¼ (25%) of defecations

2. Lumpy or hard stools (Bristol Stool Form Scale 1-2) more than ¼ (25%) of defecations

3. Sensation of incomplete evacuation more than ¼ (25%) of defecations

4. Sensation of anorectal obstruction/blockage more than ¼ (25%) of defecations

5. Manual maneuvers to facilitate more than ¼ (25%) of defecations (e.g. digital evacuation, support of the pelvic floor)

6. Fewer than three spontaneous bowel movements per week

7. Loose stools are rarely present without the use of laxatives

8. Insufficient criteria for irritable bowel syndrome

*Rome IV Criteria 2016 https://theromefoundation.org/rome-iv/rome-iv-criteria/

In most cases, constipation can be confidently diagnosed and treated in primary care.


Primary Care management prior to referral

  • Review, and if possible, adjust the dose of any constipating medications used for underlying conditions.
  • Explore lifestyle changes and non-pharmacological interventions
  • Prescribe laxatives, which can be used in combination, and doses titrated as required:
    • First line: Bulk-forming (Ispaghula) & adequate hydration (except in opioid-induced constipation)
    • Add or switch to an osmotic (Macrogol) if bulk-forming ineffective (lactulose is an alternative as second line)
    • Add stimulant if stools are soft, but difficult to pass
    • Movicol can cause uncomfortable bowel movements, rectal irritability and a lot of wind
    • Lactulose is by design gas-inducing – it mimics lactose intolerance diarrhoea
    • If patients have excessive wind consider the use of magnesium based laxatives such as magnesium hydroxide or magnesium sulphate (Milk of Magnesia & Epsom Salts) which can be combined with stimulant laxatives or suppositories
  • For patients who primarily experience difficult rectal evacuation use suppositories (Glycerine or bisacodyl) or enemas rather than high dose oral laxatives.
  • Consider referral for trans-anal irrigation.


When to consider referral

Referral to the Bowel and Bladder Specialist Service is indicated when:

· Constipation symptoms are not responding to treatment

· For assessment for trans-anal irrigation

· Faecal incontinence is present – despite consideration & management of possible impaction


Referral to the Colorectal team is indicated when:

· Cancer is suspected – as per the 2 week wait colorectal form

· Pain and bleeding on defecation (such as from an anal fissure) is severe or does not respond to conservative measures - see guidelines on Haemorrhoids and Fissures

· Anal stenosis is suspected / present and not previously investigated


Consider a routine / urgent / 2-week colorectal referral depending on level of clinical concern.

Refer to Dietician if more detailed support with diet is required.


Information required with all referrals

  • History of symptoms and examination findings including PR
  • Routine blood test results, including FBC, U&E, LFT, TFT, Bone, Coeliac screen & Ferritin
  • Management tried to date





Date Reviewed 07/08/2021

Date of Next Review 07/08/2022


Sharon Eustice, Nurse Consultant, Cornwall Partnership Trust

Dr Laura Vines, RMS GP sifter

Ms Melanie Feldman, Colorectal Surgeon RCHT 


Version No. 1.2