What counts as constipation?

Constipation is not defined by frequency alone — normal bowel habit ranges from three times a day to three times a week. The Rome IV criteria define functional constipation by the presence of two or more of the following in more than a quarter of defaecations: straining; hard or lumpy stools; a sensation of incomplete evacuation; a sensation of anorectal blockage; needing manual manoeuvres to pass stool; and fewer than three spontaneous bowel movements per week — persisting for at least three months, with onset at least six months ago. The Bristol Stool Form Scale is useful shared language: types 1 and 2 indicate constipation, types 3 and 4 are normal. Many patients use the word "constipation" to mean straining or incomplete emptying rather than infrequency, so it is always worth asking exactly what they mean.

Which medicines cause constipation?

A great many, and this is one of the most productive things to review. Common culprits: opioids (universal, dose-dependent, and — unlike the analgesic effect — no tolerance develops); anticholinergics (oxybutynin and other bladder antimuscarinics, tricyclic antidepressants, older antihistamines, many antipsychotics); calcium channel blockers, especially verapamil; iron supplements; calcium supplements and aluminium-containing antacids; 5-HT3 antagonists such as ondansetron; diuretics; and some antiepileptics. Before escalating laxative therapy in a patient with new or worsening constipation, review every medicine — substituting or stopping the responsible drug is often more effective, cheaper and safer than adding another laxative on top.

Why are my laxatives not working?

The most important explanation to consider is a defaecatory disorder — pelvic floor dyssynergia — in which the pelvic floor muscles paradoxically contract instead of relaxing during attempted defaecation, or the propulsive force is inadequate. This is an outlet problem, so laxatives, which soften stool and speed transit, cannot fix it at any dose. It accounts for approximately 25-50% of patients referred with refractory constipation. The diagnostic tests are anorectal manometry and the balloon expulsion test (inability to expel a 50mL balloon within 1-2 minutes is highly suggestive). The treatment is anorectal biofeedback — retraining the coordination of abdominal push and pelvic floor relaxation — with response rates around 70-80%. Other explanations for laxative failure: opioid-induced constipation requiring a PAMORA; undertreated faecal impaction; an untreated metabolic cause such as hypothyroidism or hypercalcaemia; and structural disease that has not been investigated.

Is long-term laxative use harmful?

For osmotic laxatives such as macrogol, no — they are not absorbed, do not cause dependence, and can be used indefinitely; macrogol has the strongest evidence base and is the preferred first-line agent. For stimulant laxatives (senna, bisacodyl, sodium picosulfate), the traditional fear of "cathartic colon" — permanent damage to colonic nerves and muscle from long-term use — is NOT supported by the evidence. Contemporary guidelines (AGA, BSG) accept regular stimulant laxative use where it is needed, and this reassurance matters because unwarranted fear leads patients to undertreat themselves and remain symptomatic. What IS important is to ensure the underlying cause has been addressed: a medication review, exclusion of metabolic and structural causes, and assessment for a defaecatory disorder in anyone who needs escalating doses.

When should constipation be investigated?

Investigate rather than simply prescribing when there are alarm features: new-onset constipation over the age of 50 without an obvious cause; rectal bleeding; iron deficiency anaemia; unintentional weight loss; a palpable abdominal or rectal mass; a family history of colorectal cancer or inflammatory bowel disease; or a progressive, unremitting change in bowel habit. Blood tests should exclude hypothyroidism, hypercalcaemia (which may indicate hyperparathyroidism or malignancy), diabetes and coeliac disease. In children, red flags for Hirschsprung's disease include failure to pass meconium in the first 48 hours of life, constipation from the first weeks of life, ribbon stools, failure to thrive, and abnormal spinal or neurological findings. In adults with refractory symptoms and no alarm features, the next step is anorectal physiology testing rather than further drug escalation.

How does GMJ News cover constipation?

GMJ News covers Rome IV criteria and the Bristol Stool Form Scale, drug-induced constipation and medication review, the three transit/functional subtypes, pelvic floor dyssynergia and biofeedback (the highest-yield missed diagnosis), macrogol vs lactulose evidence, the refutation of "cathartic colon", PAMORAs for opioid-induced constipation, faecal impaction with overflow incontinence, red flags mandating investigation, constipation in Parkinson's disease and neurogenic bowel, and paediatric constipation with Hirschsprung's red flags. Relevant to PHIG's gastroenterology, palliative care and geriatric medicine programmes.

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Constipation

GMJ News knowledge hub · last reviewed September 2026 · Georgian Medical Journal

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Chronic constipation — defined by the Rome IV criteria as infrequent, difficult or incomplete defaecation persisting for at least three months — affects approximately 14% of the global adult population, rising sharply with age, female sex, low physical activity and polypharmacy, and is among the most common reasons for primary care consultation and laxative prescription worldwide (WHO). Two clinical points are consistently under-recognised: first, that constipation is frequently iatrogenic — opioids, anticholinergics, calcium channel blockers, iron, antipsychotics and antidepressants are common causes that respond to medication review rather than escalating laxatives; and second, that a substantial minority of refractory cases are caused by pelvic floor dyssynergia (paradoxical contraction of the pelvic floor during defaecation), which does not respond to laxatives at all but responds very well to anorectal biofeedback therapy — making anorectal physiology assessment the correct next step in laxative-refractory constipation rather than further drug escalation.

Key messages

14% of adults globally — and frequently iatrogenic

Chronic constipation affects approximately 14% of the global adult population, rising sharply with age, female sex, low physical activity, low fibre and fluid intake, and polypharmacy. The most under-recognised point: constipation is very often DRUG-INDUCED. Common culprits: opioids (universal and dose-dependent); anticholinergics (oxybutynin, TCAs, antihistamines, antipsychotics); calcium channel blockers (verapamil in particular); iron supplements; calcium supplements and antacids containing aluminium; 5-HT3 antagonists (ondansetron); and diuretics. A medication review is frequently more effective than escalating laxatives.

Pelvic floor dyssynergia — laxative-refractory constipation that laxatives cannot fix

Approximately 25-50% of patients referred with refractory chronic constipation have a defaecatory disorder — paradoxical contraction (or failure to relax) of the puborectalis and external anal sphincter during attempted defaecation, with inadequate propulsive force. These patients do not respond to laxatives at any dose, because the problem is outlet obstruction, not slow transit. Diagnosis: anorectal manometry with balloon expulsion test (a simple, highly informative bedside-adjacent test — inability to expel a 50mL water-filled balloon within 1-2 minutes is strongly suggestive). Treatment: ANORECTAL BIOFEEDBACK — response rates approximately 70-80%, substantially better than any laxative, and durable. Recognising this group is one of the highest-yield interventions in gastroenterology.

Osmotic laxatives first — macrogol has the best evidence

Stepwise pharmacological approach. First-line: bulk-forming (ispaghula — only with adequate fluid; avoid in opioid-induced constipation and in suspected obstruction) and osmotic laxatives — macrogol/polyethylene glycol has the strongest evidence base (Cochrane: superior to lactulose for stool frequency, consistency and abdominal pain, with less bloating and flatulence). Second-line: stimulants (bisacodyl, senna, sodium picosulfate) — the historical fear of "cathartic colon" and permanent damage from long-term stimulant use is NOT supported by evidence; they are appropriate for regular use where needed. Third-line: prucalopride (5-HT4 agonist, prokinetic); linaclotide and plecanatide (guanylate cyclase-C agonists); lubiprostone (chloride channel activator).

Opioid-induced constipation needs a different drug class

Opioid-induced constipation (OIC) is mediated by peripheral mu-opioid receptors in the enteric nervous system, and unlike analgesia it does NOT show tolerance — it persists for the entire duration of opioid therapy. Standard laxatives are frequently inadequate. PAMORAs (peripherally acting mu-opioid receptor antagonists) target the mechanism directly without crossing the blood-brain barrier and therefore without reversing analgesia: naloxegol, naldemedine, methylnaltrexone (subcutaneous — particularly useful in palliative care), and oral naloxone in fixed combination with oxycodone. Bulk-forming laxatives should be AVOIDED in OIC — they can precipitate obstruction in a hypomotile gut.

Faecal impaction and overflow — the paradox of "diarrhoea" from constipation

A critical trap, especially in elderly and immobile patients and in children. Hard impacted stool in the rectum causes liquid stool to leak around it — presenting as faecal incontinence or apparent diarrhoea. Prescribing an antidiarrhoeal in this situation is actively harmful. Diagnosis: digital rectal examination (mandatory in the assessment of any new faecal incontinence or unexplained diarrhoea in an at-risk patient) ± abdominal X-ray. Management: disimpaction — high-dose oral macrogol regimens, with rectal measures (glycerol suppositories, phosphate or arachis oil enemas) and, occasionally, manual evacuation — followed by an ongoing maintenance laxative regimen, which is essential to prevent recurrence.

Red flags mandate investigation — do not just prescribe laxatives

Alarm features requiring investigation for colorectal cancer or other structural disease: new-onset constipation in a patient over 50 without an obvious cause; rectal bleeding; iron deficiency anaemia; unintentional weight loss; a palpable abdominal or rectal mass; a family history of colorectal cancer or IBD; and any progressive or unremitting change in bowel habit. Also consider and exclude metabolic and neurological causes: hypothyroidism; hypercalcaemia (particularly hyperparathyroidism or malignancy); diabetes with autonomic neuropathy; Parkinson's disease (constipation frequently PRECEDES motor symptoms by years); multiple sclerosis; spinal cord lesions; and, in infants and children, Hirschsprung's disease.

Key statistics

~14%

global adult prevalence of chronic constipation

Rome Foundation/AGA

25-50%

of refractory constipation referrals have a defaecatory disorder — laxatives will not work

AGA/ANMS

70-80%

response rate to anorectal biofeedback in pelvic floor dyssynergia

AGA/Gastroenterology

Macrogol

superior to lactulose for stool frequency, consistency and pain, with less bloating (Cochrane)

Cochrane

PAMORAs

for opioid-induced constipation — target the mechanism without reversing analgesia

AGA/ESMO

No evidence

for "cathartic colon" — long-term stimulant laxative use is not proven to damage the colon

AGA/BSG

Chronic constipation — treatment response by mechanism (AGA/ACG)

Source: AGA/ACG. Biofeedback is the most effective treatment for defaecatory disorders, which do not respond to laxatives.

Glossary of key terms

Rome IV functional constipation criteria
Rome FoundationMust include TWO OR MORE of the following, present in more than 25% of defaecations: straining; lumpy or hard stools (Bristol type 1-2); sensation of incomplete evacuation; sensation of anorectal obstruction or blockage; manual manoeuvres to facilitate defaecation (digital evacuation, support of the pelvic floor); fewer than three spontaneous bowel movements per week. Additionally: loose stools are rarely present without laxative use; and insufficient criteria for IBS (the distinguishing feature being that abdominal pain is not the predominant symptom — where pain predominates, the diagnosis is IBS-C). Criteria fulfilled for the last 3 months with onset at least 6 months before diagnosis.

Bristol Stool Form Scale
Clinical toolA validated 7-point visual scale of stool form, developed at Bristol Royal Infirmary, that correlates with colonic transit time. Type 1: separate hard lumps, hard to pass (severe constipation, slow transit). Type 2: sausage-shaped but lumpy (mild constipation). Type 3: sausage-shaped with cracks on the surface (normal). Type 4: smooth, soft sausage or snake (normal — the ideal). Type 5: soft blobs with clear-cut edges (lacking fibre, tending to loose). Type 6: fluffy pieces with ragged edges, mushy (mild diarrhoea). Type 7: entirely liquid, no solid pieces (diarrhoea). Its value is that it gives patients and clinicians shared, objective language — far more reliable than asking about "constipation," a word patients use to mean widely different things (infrequency, straining, hardness or incomplete evacuation).

Constipation subtypes by transit and function
NeurogastroenterologyThree principal subtypes, which require different treatment: (1) Normal transit constipation — the commonest; transit is objectively normal but the patient perceives difficulty; overlaps with IBS-C; responds to fibre, osmotic laxatives and reassurance. (2) Slow transit constipation — delayed colonic transit demonstrable on radiopaque marker study or wireless motility capsule; associated with reduced interstitial cells of Cajal and impaired colonic high-amplitude propagating contractions; responds better to prokinetics (prucalopride) and stimulants. (3) Defaecatory (evacuation) disorder — normal or slow transit with failure of the mechanics of evacuation (pelvic floor dyssynergia, inadequate propulsive force, rectocele, rectal intussusception); responds to biofeedback, NOT to laxatives. Many patients have mixed slow transit plus a defaecatory disorder — which is why treating the outlet problem often "unblocks" apparent laxative resistance.

Anorectal manometry and balloon expulsion test
DiagnosticsThe essential investigations in laxative-refractory constipation. High-resolution anorectal manometry measures resting and squeeze anal pressures, the rectoanal inhibitory reflex (RAIR — absent in Hirschsprung's disease), rectal sensation thresholds, and the pressure pattern during simulated defaecation (identifying dyssynergic patterns I-IV — inadequate push, paradoxical contraction, or both). Balloon expulsion test: a 50mL water-filled balloon is placed in the rectum and the patient attempts to expel it in privacy; inability to do so within 1-2 minutes strongly suggests a defaecatory disorder (high negative predictive value). Defaecography (fluoroscopic or MR) adds structural information — rectocele, enterocele, intussusception, perineal descent. These tests identify the substantial subgroup for whom biofeedback, not more laxative, is the answer.

Constipation in Parkinson's disease and neurological conditions
Neurology/GIConstipation is one of the most common non-motor features of Parkinson's disease and, importantly, frequently PRECEDES the onset of motor symptoms by 10-20 years — consistent with the Braak hypothesis of α-synuclein pathology ascending from the enteric nervous system via the vagus. It affects up to 80% of established Parkinson's patients, and is compounded by dopaminergic and anticholinergic medication. It is also prominent in: multiple sclerosis; spinal cord injury (neurogenic bowel — requiring structured bowel management programmes with planned rectal stimulation); diabetic autonomic neuropathy; and stroke. Management in these groups is systematic and preventive (scheduled toileting after meals to exploit the gastrocolic reflex, osmotic laxatives, suppositories) rather than reactive.

Paediatric constipation and Hirschsprung's disease
PaediatricsFunctional constipation accounts for over 95% of childhood constipation and typically begins around toilet training, dietary change or a painful defaecation experience, creating a withholding cycle. Management (NICE/ESPGHAN): disimpaction with escalating macrogol, then MAINTENANCE macrogol for months — undertreatment and premature withdrawal are the commonest causes of relapse — combined with behavioural measures (regular post-meal toilet sitting, reward systems, footstool). RED FLAGS suggesting organic disease, particularly Hirschsprung's: failure to pass meconium within 48 hours of birth; constipation from the first weeks of life; ribbon stools; explosive stool on rectal examination withdrawal; failure to thrive; abdominal distension; abnormal neurological or spinal examination (sacral dimple, tuft of hair). Hirschsprung's diagnosis: absent RAIR on manometry, confirmed by suction rectal biopsy showing aganglionosis.

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