📋 Key Information Summary
- Chronic constipation is defined by Rome IV criteria: ≥2 of 6 symptoms for ≥3 months with symptom onset ≥6 months prior — straining, lumpy/hard stools, sensation of incomplete evacuation, anorectal obstruction, manual manoeuvres, <3 spontaneous bowel movements per week.
- Always exclude alarm features before diagnosing functional constipation: rectal bleeding, unintentional weight loss, iron-deficiency anaemia, new onset age ≥50 years, acute change in bowel habit in older adults, family history of colorectal cancer, or a palpable abdominal/rectal mass.
- Medication review is critical — opioids, anticholinergics, calcium-channel blockers, iron supplements, calcium supplements, and serotonergic agents are the most common iatrogenic causes in Australian practice.
- First-line management centres on dietary fibre (≥30 g/day), adequate hydration (≥1.5–2 L/day), regular physical activity, and osmotic laxatives — polyethylene glycol (PEG/Movicol®) is the preferred first-choice laxative.
- Titrating PEG: start with 1 sachet (13.8 g) daily and increase by half to one sachet every 2–3 days until soft, easy-to-pass stools are achieved; doses up to 3 sachets/day may be required.
- Second-line therapy includes stimulant laxatives (senna, bisacodyl) — either as rescue or scheduled adjunct — and newer agents including prucalopride (Resotrans®) and linaclotide (Constella®) for refractory cases.
- Pelvic floor dysfunction (dyssynergic defaecation) should be suspected when patients strain excessively, report incomplete emptying, or have a normal transit study; anorectal manometry and biofeedback therapy are the gold standard for diagnosis and treatment.
- Prucalopride (5-TH4 agonist) is PBS-listed for women with chronic constipation refractory to laxatives (Authority Required); linaclotide (guanylate cyclase-C agonist) is also PBS-listed for patients failing standard laxative therapy.
- Refer to gastroenterology if symptoms persist despite ≥3 months of optimised therapy, if there is suspicion of mechanical obstruction or secondary cause, or for patients aged ≥45–50 years without recent colonoscopic evaluation.
- Special populations: pregnancy (PEG preferred, avoid stimulant laxatives long-term), paediatrics (PEG first-line per PIPES guideline), elderly (increased fall risk with straining, review polypharmacy), renal/hepatic (magnesium and sodium caution in renal impairment).
- Aboriginal and Torres Strait Islander populations have higher rates of constipation linked to low dietary fibre intake, remote access barriers, and limited specialist availability — culturally safe education and community-level interventions are essential.
- Ongoing monitoring: Bristol Stool Form Scale (target type 3–4), reassess fibre and fluid intake at each visit, audit laxative use, and screen for secondary causes if initial response is poor.
Introduction & Australian Epidemiology
Chronic constipation is one of the most common gastrointestinal complaints managed in Australian primary care, affecting an estimated 14–20% of the adult population. It is associated with significant reductions in quality of life, increased healthcare utilisation, and substantial economic burden. The condition encompasses functional constipation (FC), opioid-induced constipation (OIC), constipation-predominant irritable bowel syndrome (IBS-C), and secondary constipation arising from systemic disease, medications, or anatomical causes.
In Australia, chronic constipation accounts for approximately 1.2 million general practice consultations annually and is responsible for a significant proportion of over-the-counter laxative sales. The condition is more prevalent in women (OR 2.2), older adults, those with low dietary fibre intake, sedentary individuals, and those in lower socioeconomic groups. Aboriginal and Torres Strait Islander Australians experience disproportionately higher rates of gastrointestinal disease and may face additional barriers to timely diagnosis and management.
This guideline provides an evidence-based framework for the evaluation and management of chronic and refractory constipation in the Australian healthcare context, with emphasis on the stepped-care approach endorsed by the Gastroenterological Society of Australia (GESA), Royal Australian College of General Practitioners (RACGP), and Therapeutic Guidelines (eTG).
Australian burden: Prevalence 14–20% in adults, ~25% in those aged ≥65 years. Annual direct healthcare costs estimated at over AUD 0 million. Laxative use is among the top 20 PBS expenditure categories nationally.
Initial Evaluation & Alarm Features
Rome IV Diagnostic Criteria for Functional Constipation
Functional constipation is diagnosed when the patient reports ≥2 of the following 6 criteria for ≥3 months, with symptom onset at least 6 months prior to diagnosis:
| Criterion | Description |
|---|---|
| 1. Straining | Straining during >25% of defaecations |
| 2. Lumpy stools | Lumpy or hard stools (Bristol type 1–2) in >25% of defaecations |
| 3. Incomplete evacuation | Sensation of incomplete evacuation in >25% of defaecations |
| 4. Anorectal obstruction | Sensation of anorectal obstruction/blockage in >25% of defaecations |
| 5. Manual manoeuvres | Need for manual manoeuvres (digital evacuation, perineal/pelvic support) in >25% of defaecations |
| 6. Few bowel movements | Fewer than 3 spontaneous bowel movements per week |
Loose stools should rarely be present without the use of laxatives, and insufficient criteria for IBS should be met. The Bristol Stool Form Scale should be used routinely to characterise stool consistency (target types 3–4 with treatment).
Medication Review — Iatrogenic Causes
A thorough medication review is a cornerstone of initial evaluation. The following commonly prescribed and over-the-counter agents in Australian practice may cause or exacerbate constipation:
| Drug Class | Examples | Mechanism |
|---|---|---|
| Opioids | Codeine, oxycodone, morphine, tapentadol, tramadol | μ-receptor activation in GI tract; reduced motility and secretion |
| Anticholinergics | Oxybutynin, solifenacin, amitriptyline, benztropine, hyoscine | Reduced parasympathetic GI motility |
| Calcium-channel blockers | Verapamil, nifedipine, diltiazem | Smooth muscle relaxation in GI tract |
| Iron supplements | Ferrous sulfate, ferrous fumarate | Direct irritant effect and altered gut motility |
| Calcium supplements | Calcium carbonate (Caltrate®) | Reduced colonic motility |
| Serotonergic agents | SSRIs (paroxetine most common), ondansetron | 5-HT3 antagonism; reduced GI motility |
| Others | Clonidine, bile acid sequestrants (cholestyramine), aluminium antacids, NSAIDs | Variable mechanisms |
Opioid-induced constipation (OIC): Affects up to 80% of patients on long-term opioids. Standard laxatives are often ineffective due to peripheral μ-receptor mechanisms. Consider naloxegol (Moventig®), methylnaltrexone (Relistor®), or lubiprostone specifically for OIC if standard laxative therapy fails. Prevention with a stimulant laxative + osmotic laxative should be co-prescribed when initiating opioids.
Alarm Features (Red Flags) Requiring Urgent Investigation
The presence of any alarm feature mandates prompt investigation — typically with colonoscopy — before attributing symptoms to a functional aetiology:
- Rectal bleeding or blood in stool (not attributable to haemorrhoids)
- Unintentional weight loss (>5% body weight in 6 months)
- Iron-deficiency anaemia (low ferritin, low Hb, low MCV)
- New-onset constipation in a patient aged ≥50 years
- Acute change in bowel habit in an older adult (≥65 years)
- Family history of colorectal cancer (first-degree relative)
- Palpable abdominal or rectal mass
- Progressive worsening despite appropriate treatment
- Symptoms suggesting obstruction: vomiting, colicky abdominal pain, distension
Initial History and Examination
A comprehensive evaluation should include:
- Onset, duration, frequency, and consistency of bowel movements (use Bristol Stool Form Scale)
- Associated symptoms: straining, incomplete evacuation, abdominal pain, bloating
- Dietary history — fibre and fluid intake (average Australian intake ~20–25 g/day, target ≥30 g/day)
- Physical activity level
- Complete medication and supplement review (including over-the-counter)
- Obstetric and gynaecological history in women (pelvic floor injury, hysterectomy)
- Previous investigations and treatments tried
- Abdominal examination for masses, distension, tenderness
- Digital rectal examination (DRE) — essential to assess resting and squeeze anal tone, rectal mass, faecal impaction, and paradoxical contraction of the puborectalis
First-Line Management
First-line management of chronic constipation follows a structured, stepwise approach incorporating lifestyle modification and osmotic laxative therapy. This approach aligns with Therapeutic Guidelines (eTG), GESA recommendations, and international consensus (AGA, ACG).
Lifestyle and Dietary Modification
1
Increase Dietary Fibre
Target ≥30 g/day of mixed soluble and insoluble fibre. Encourage whole grains, fruits (prunes, kiwifruit), vegetables, legumes, and psyllium husk (e.g., Metamucil® or generic). Fibre supplementation with psyllium isosmotic (3–4 g/day titrated to 6–12 g/day) is recommended when dietary modification alone is insufficient.
2
Adequate Hydration
Encourage ≥1.5–2 L of non-caffeinated fluids daily. Adequate hydration is particularly important when increasing fibre intake to avoid exacerbation of symptoms. There is no strong evidence that extra water beyond normal requirements improves constipation, but dehydration worsens it.
3
Regular Physical Activity
Encourage ≥150 minutes of moderate-intensity activity per week (e.g., brisk walking, cycling). Regular exercise improves colonic transit and overall bowel function. A structured daily walking programme of 20–30 minutes is a practical recommendation for most patients.
4
Toilet Habit Training
Encourage a regular toilet routine — attempt defaecation 15–30 minutes after meals (exploiting the gastrocolic reflex), ideally after breakfast. Use a footstool to adopt a squatting posture (knees above hips). Do not suppress the urge to defaecate.
First-Line Laxative Therapy: Osmotic Laxatives
Polyethylene glycol (PEG) is the recommended first-choice osmotic laxative for chronic constipation. It is an iso-osmotic, non-absorbable agent with a strong evidence base, good tolerability, and PBS availability.
Polyethylene Glycol (PEG) 3350
Movicol® · Osmolax® · MacroLax® · Generic · Osmotic laxative
Adult dose
1 sachet (13.8 g in 125 mL water) once daily; titrate by ½–1 sachet every 2–3 days to achieve soft stools (Bristol type 3–4). Usual range 1–3 sachets daily.
Paediatric dose
0.4–0.8 g/kg/day (≈1–4 sachets daily depending on age). Start low and titrate. Use Movicol®-Half (6.9 g) sachets for younger children.
Route
Oral — dissolved in water (or juice for palatability)
Duration
Ongoing as required; may be needed long-term. Review at 4–6 weeks.
Renal adjustment
Generally safe; caution with electrolyte-containing PEG formulations (Movicol®) in severe renal impairment (eGFR <30). Use PEG-only (Osmolax®) which is electrolyte-free.
Hepatic adjustment
No dose adjustment required
PBS status
✔ PBS General Benefit
Fibre supplementation tip: Psyllium husk (Metamucil® or generic) is a well-tolerated bulk-forming agent with evidence for improving stool frequency and consistency. Start at 1 teaspoon (3–4 g) daily in 250 mL water and increase gradually to 2–3 teaspoons daily. Adequate fluid intake is essential to prevent faecal impaction.
Psyllium Husk (Bulk-Forming Agent)
Psyllium Husk (Ispaghula)
Metamucil® · Fybogel® · Generic · Bulk-forming laxative
Adult dose
3.5 g (1 sachet or 1 tsp) in 250 mL water, 1–3 times daily. Start once daily and titrate.
Paediatric dose
½–1 sachet daily (age ≥6 years); not recommended <6 years due to choking risk.
Route
Oral — mixed in water, take immediately
Renal adjustment
No adjustment required
PBS status
✘ Not PBS listed (OTC)
Lactulose (Alternative Osmotic Laxative)
Lactulose
Duphalac® · Actilax® · Generic · Osmotic laxative (non-absorbable disaccharide)
Adult dose
15–30 mL once or twice daily, titrated to effect
Paediatric dose
1–5 mL/kg/day in divided doses; 5–10 mL daily for infants, 10–15 mL for children
Route
Oral
Renal adjustment
Use with caution — may cause osmotic diarrhoea and electrolyte disturbance in renal impairment
PBS status
✔ PBS General Benefit
Note: Lactulose is generally less well-tolerated than PEG due to bloating, flatulence, and sweet taste. PEG is preferred as first-line per eTG and AGA guidelines. Lactulose may be used as an alternative in patients who cannot tolerate PEG or in the management of hepatic encephalopathy (dual indication).
Second-Line & Refractory Management
When first-line measures (fibre, fluids, exercise, and optimised osmotic laxative therapy) have been trialled for an adequate duration (4–6 weeks at maximum tolerated dose) without satisfactory response, a stepwise escalation to second-line therapies is warranted. The management approach depends on whether the underlying issue is slow transit constipation, pelvic floor dysfunction (dyssynergic defaecation), or both.
Stimulant Laxatives
Stimulant laxatives are the most common second-line agents. They may be used as rescue therapy (prn) or as scheduled adjunctive therapy in patients with refractory symptoms.
Senna
Senokot® · Generic · Stimulant laxative (anthraquinone)
Adult dose
15–30 mg (1–2 tablets) at night; titrate to 4 tablets at night. Usual effective dose 15–60 mg nocte.
Paediatric dose
1 month–2 years: 2.5 mg once daily; 2–6 years: 5 mg once daily; 6–12 years: 7.5–15 mg once daily; >12 years: adult dose
Route
Oral
Renal adjustment
No adjustment required
PBS status
✔ PBS General Benefit
Bisacodyl
Dulcolax® · Generic · Stimulant laxative (diphenylmethane derivative)
Adult dose
10 mg orally at night; or 10 mg PR (suppository) for more rapid effect (30–60 min).
Paediatric dose
4–10 years: 5 mg at night; ≥10 years: adult dose
Route
Oral or rectal (suppository or enema)
Renal adjustment
No adjustment required
PBS status
✔ PBS General Benefit
Myth-busting: Chronic stimulant laxative use does not cause anatomical colonic damage (cathartic colon) at standard doses. Historical concerns were based on older case reports of abuse with doses far exceeding therapeutic ranges. Current evidence supports their safety for long-term use in chronic constipation.
Secretagogues (for Refractory Functional Constipation)
Linaclotide
Constella® · Guanylate cyclase-C agonist
Adult dose
290 µg orally once daily, 30 minutes before first meal
Mechanism
Activates GC-C on intestinal epithelium → increased intestinal fluid secretion, accelerated transit, reduced visceral pain
Key caution
Contraindicated in patients with known or suspected mechanical GI obstruction. Diarrhoea is the most common adverse effect (16–20%); discontinue if severe. Paediatric safety not established.
Renal adjustment
No adjustment required
Hepatic adjustment
No dose adjustment; use with caution in severe hepatic impairment
PBS status
⚠ Authority Required — For chronic constipation refractory to standard laxatives for ≥3 months
Prokinetic Agent
Prucalopride
Resotrans® · Selective 5-HT4 receptor agonist (prokinetic)
Adult dose
2 mg orally once daily. 1 mg daily if significant renal impairment (eGFR 15–30).
Mechanism
Stimulates colonic motility via 5-HT4 receptors on enteric neurons; increases colonic transit and frequency of spontaneous bowel movements.
Key caution
Contraindicated in intestinal obstruction, Crohn's disease with active severe inflammation, toxic megacolon/megarectum. Common side effects: headache (19%), nausea (13%), abdominal pain (16%), diarrhoea (10%). Caution in severe cardiac disease (QT prolongation risk).
Renal adjustment
eGFR 15–30: 1 mg once daily; eGFR <15 or dialysis: 1 mg once daily (limited data)
PBS status
⚠ Authority Required — Women with chronic constipation refractory to laxatives
Pelvic Floor Dysfunction (Dyssynergic Defaecation)
Pelvic floor dysfunction is present in up to 50% of patients with refractory constipation. It is characterised by paradoxical contraction (dyssynergia) or inadequate relaxation of the puborectalis and external anal sphincter during defaecation, or inadequate rectal propulsive force (inadequate defaecation propulsion).
Clinical suspicion: Patients report excessive straining, sensation of incomplete evacuation, need for perineal or vaginal splinting to defaecate, and normal or near-normal stool frequency but difficulty with actual evacuation.
Diagnostic approach:
- Anorectal manometry (ARM) — Gold standard for diagnosing dyssynergic defaecation. Measures resting and squeeze anal pressures, rectoanal inhibitory reflex, and balloon expulsion test (inability to expel a 50 mL balloon in ≤1 minute is abnormal).
- Defaecography (evacuating proctography) — Identifies anatomical causes: rectocoele, intussusception, sigmoidocoele. Available in major tertiary centres (MBS item 32158).
- Colonic transit study (radiopaque marker study) — Distinguishes slow transit constipation from outlet obstruction. Patients stop laxatives 72 hours prior and ingest radiopaque markers (Sitz markers); an abdominal X-ray is performed on day 5 (MBS item 57713).
Biofeedback therapy is the first-line treatment for dyssynergic defaecation. It involves supervised training to coordinate pelvic floor and abdominal muscle function during defaecation. Typical programmes involve 4–6 sessions over 6–12 weeks. Evidence shows 60–80% improvement in symptoms. Refer to a specialised pelvic floor physiotherapist or gastroenterology service.
Opioid-Induced Constipation — Specific Agents
Naloxegol
Moventig® · Peripheral μ-opioid receptor antagonist (PAMORA)
Adult dose
25 mg orally once daily on an empty stomach (morning, ≥1 hour before or 2 hours after first meal). 12.5 mg if eGFR <60 or concomitant CYP3A4 inhibitors (diltiazem, verapamil, erythromycin).
Key caution
Contraindicated with methadone. Do not use if GI obstruction is suspected. Does not reverse central analgesic effect of opioids.
Renal adjustment
eGFR <60: 12.5 mg once daily. Not recommended in eGFR <15 or dialysis.
PBS status
⚠ Authority Required — Opioid-induced constipation not responding to standard laxatives
Methylnaltrexone
Relistor® · Peripheral μ-opioid receptor antagonist (injectable)
Adult dose
8 mg (if body weight 38–61 kg) or 12 mg (if >61 kg) SC every other day. May be given daily if required (max daily dose).
Route
Subcutaneous injection
Renal adjustment
eGFR <30: 50% of standard dose (4 mg or 6 mg every other day)
PBS status
⚠ Authority Required — Palliative care context, OIC refractory to oral PAMORA
Stepwise Approach Summary
Step 1
First-Line
Dietary fibre ≥30 g/day (± psyllium), adequate fluids, exercise, toilet training, PEG 1–3 sachets daily
Duration: 4–6 weeks trial
Step 2
Second-Line
Add stimulant laxative (senna/bisacodyl). Assess for pelvic floor dysfunction with ARM if suspected. Continue PEG.
Duration: 4–6 weeks trial
Step 3
Refractory / Specialist
Secretagogue (linaclotide) or prokinetic (prucalopride). Biofeedback for dyssynergia. Specialist referral for transit studies, defaecography, or surgical evaluation.
Setting: Gastroenterology / Colorectal Surgery
Investigations
Investigations should be guided by clinical suspicion. Most patients with functional constipation can be diagnosed and managed without extensive investigations. The following tests should be considered based on clinical context:
Essential
Full blood count (FBC) and iron studies
Screen for iron-deficiency anaemia (low ferritin, low Hb, low MCV) as an alarm feature suggestive of occult GI blood loss. Available in all Australian pathology labs. MBS item 65070.
Essential
Thyroid function tests (TFTs)
Hypothyroidism is a common secondary cause. TSH is the primary screening test. MBS item 66716.
Essential
Serum calcium, glucose, renal function (eGFR)
Hypercalcaemia, diabetes mellitus, and chronic kidney disease are recognised secondary causes. MBS item 66526.
Essential
Digital rectal examination (DRE)
Clinical assessment of anal tone, rectal masses, faecal impaction, and puborectalis function (instruct patient to "push out" and assess paradoxical contraction).
Available
Colonoscopy
Indicated for alarm features, age ≥45–50 without recent colon evaluation, or refractory symptoms. MBS item 32222. Available at most public and private endoscopy centres.
Available
Abdominal X-ray (KUB)
Useful for assessing faecal loading, excluding obstruction, and as part of a transit study. MBS item 57713.
Available
Colonic transit study (Sitz markers)
Patient ingests radiopaque markers on day 1; plain AXR on day 5. Retention of >80% of markers suggests slow transit constipation. MBS item 57713. Available at major hospitals.
Specialist
Anorectal manometry (ARM)
Gold standard for pelvic floor dyssynergia. Measures resting and squeeze sphincter pressures, rectoanal inhibitory reflex, and balloon expulsion. Requires referral to gastroenterology or motility specialist.
Specialist
Defaecating proctography (MR defaecography)
Evaluates anatomical abnormalities during defaecation — rectocoele, intussusception, perineal descent. MRI defaecography is increasingly preferred (no radiation). MBS item 63514. Available at tertiary centres.
Specialist
Wireless motility capsule (SmartPill)
Measures whole-gut transit time. Emerging availability in Australian tertiary centres. Not currently MBS-listed. Useful for evaluating regional transit abnormalities.
Monitoring
Ongoing monitoring is essential for patients with chronic constipation to ensure treatment adequacy, medication safety, and early detection of secondary causes:
Week 2
Telephone or telehealth review — assess initial response to PEG dose titration, side effects, adherence to fibre and fluid recommendations. Adjust dose if bowel movements remain infrequent or stools remain hard.
Week 6
In-person review — assess Bristol Stool Form Scale (target type 3–4), frequency of spontaneous bowel movements (target ≥3/week), straining, and symptom burden. Review medication adherence. Consider adding stimulant laxative if inadequate response.
Month 3
Comprehensive review — assess for alarm features that may have developed, repeat bloods if anaemia was found at baseline, consider referral if symptoms remain refractory. Document trial of at least two classes of laxative at adequate doses before labelling as refractory.
6-monthly
Long-term monitoring for patients on chronic laxative therapy — assess efficacy, review for secondary causes, monitor electrolytes if on magnesium-containing laxatives or lactulose, and ensure colonoscopy is up to date in patients ≥45–50 years.
Monitoring Tools
- Bristol Stool Form Scale (BSFS): Patient self-report of stool consistency on a 1–7 scale. Target types 3 (soft, sausage-shaped with cracks) to 4 (smooth, sausage-shaped). Available as a patient handout.
- Patient Assessment of Constipation Symptoms (PAC-SYM): Validated 12-item questionnaire assessing abdominal, rectal, and stool symptoms. Useful for tracking treatment response in research and clinical practice.
- Patient Assessment of Constipation Quality of Life (PAC-QOL): 28-item questionnaire measuring quality of life across four domains — physical discomfort, psychosocial discomfort, worries and concerns, and satisfaction.
- Bowel diary: Record of daily stool frequency, consistency (BSFS type), straining episodes, laxative use, fibre and fluid intake. Recommended for 1–2 weeks before clinic review.
Special Populations
Pregnancy
First-line: PEG (Movicol®)
Safe in all trimesters. No teratogenicity reported. Start with 1 sachet daily and titrate. Adequate fluids and fibre remain the cornerstone.
Second-line: Lactulose
Safe in pregnancy. May cause bloating. Use if PEG is not tolerated.
Avoid/Use with caution:
Stimulant laxatives (senna, bisacodyl) — avoid chronic use; may be used short-term if osmotic laxatives fail. Docusate sodium — probably safe but limited evidence. Magnesium-containing laxatives — avoid in renal impairment. Avoid castor oil. Prucalopride and linaclotide are not recommended in pregnancy (insufficient safety data).
Paediatrics
First-line: PEG (Movicol® / Movicol®-Half)
0.4–0.8 g/kg/day (PIPES guideline). Start low and titrate. Most children with functional constipation respond to PEG monotherapy. Continued for months to years as needed.
Add-on: Senna or bisacodyl
For children not responding to PEG alone. Age-appropriate dosing. Short-course disimpaction regimen if faecal loading: high-dose PEG 1–1.5 g/kg/day for 3–7 days (PIPES protocol).
Avoid:
Prucalopride, linaclotide, naloxegol — not approved for paediatric use in Australia. Mineral oil (paraffin) — aspiration risk in young children. Psyllium — choking risk <6 years.
Elderly (≥65 years)
Key considerations
Constipation prevalence ~25% in community-dwelling elderly and >50% in residential aged care. Polypharmacy is a major contributor — review all medications. Straining-related complications include syncope, falls, and cardiac events (Valsalva).
First-line: PEG
Use electrolyte-free PEG (Osmolax®) in patients with renal impairment or heart failure to avoid sodium/potassium load. Start at 1 sachet daily and titrate slowly.
Faecal impaction
Disimpaction with high-dose PEG (2–3 sachets/day for 3 days) or sodium phosphate enema (Fleet®). Oral macrogol-based disimpaction preferred over enemas in frail patients. Avoid sodium phosphate enemas in renal impairment (hyperphosphataemia risk).
Renal Impairment
Preferred: PEG (electrolyte-free formulation)
Osmolax® or MacroLax® (PEG-only without electrolytes) is preferred over Movicol® in severe renal impairment (eGFR <30) to avoid sodium and potassium loading.
Caution with:
Magnesium-containing laxatives (risk of hypermagnesaemia), lactulose (risk of dehydration and electrolyte imbalance), sodium phosphate enemas (hyperphosphataemia risk). Prucalopride dose reduction to 1 mg daily if eGFR 15–30.
Hepatic Impairment
Preferred: PEG + lactulose
Lactulose is particularly useful as it serves dual purpose: treatment of constipation and prophylaxis/management of hepatic encephalopathy (reduces ammonia absorption). No dose adjustment of PEG required.
Avoid/Use with caution:
Magnesium-containing laxatives (impaired hepatic metabolism). Avoid lactulose overload causing diarrhoea with consequent dehydration and worsening encephalopathy. Stimulant laxatives are generally safe.
Immunocompromised
Key considerations
Patients on immunosuppressive therapy (post-transplant, chemotherapy, biologics) are at increased risk of constipation from concurrent medications (antiemetics — ondansetron, 5-HT3 antagonists; opioids for cancer pain; vinca alkaloids). Constipation may mask or mimic GI infections (CMV colitis, C. difficile).
Management
PEG is first-line. Prophylactic laxatives should be co-prescribed with opioids and vinca alkaloids. Avoid rectal procedures if neutropenic (ANC <0.5 × 10⁹/L) due to mucosal injury risk. Investigate alarm features promptly given higher risk of sinister pathology.
Aboriginal and Torres Strait Islander Health Considerations
Aboriginal and Torres Strait Islander Health
When to Refer
Timely referral to gastroenterology or colorectal surgery is essential for patients who meet the following criteria:
Refer to Gastroenterology:
- Persistent symptoms despite ≥3 months of optimised first- and second-line therapy (fibre, fluids, PEG at adequate dose ± stimulant laxatives)
- Suspected secondary cause: hypothyroidism, hypercalcaemia, neurological disease (e.g., spinal cord injury, multiple sclerosis, Parkinson's disease), systemic sclerosis
- Suspected pelvic floor dysfunction: excessive straining, incomplete evacuation, need for manual manoeuvres — requires anorectal manometry and biofeedback assessment
- Age ≥45–50 years without colonoscopy performed within the previous 5 years — colonoscopic evaluation recommended before attributing symptoms to functional constipation
- Failure to respond to secretagogues or prokinetics, or need for specialist access to these agents (Authority Required PBS prescriptions may require specialist initiation)
- Consideration of colonic transit studies to distinguish slow transit from outlet dysfunction
Urgent referral / Same-day assessment:
- Suspected bowel obstruction: colicky abdominal pain, vomiting, absolute constipation, abdominal distension, absent bowel sounds
- Acute-onset constipation with alarm features (rectal bleeding, weight loss, mass) in older adults
- Faecal impaction not responding to oral disimpaction regimens in community setting — may require hospital admission for manual disimpaction or rectal interventions
- Toxic megacolon (rare but critical): abdominal distension, tenderness, systemic toxicity
Colorectal Surgery Referral
- Significant rectocoele or intussusception identified on defaecography causing obstructive defaecation symptoms
- Severe slow transit constipation refractory to all medical therapy — subtotal colectomy with ileorectal anastomosis may be considered in highly selected patients (requires multidisciplinary team assessment)
- Large rectal mass or significant anatomical pathology identified on colonoscopy
Other Referral Pathways
- Pelvic floor physiotherapy: For patients with dyssynergic defaecation confirmed or suspected on clinical grounds; biofeedback therapy is first-line for pelvic floor dysfunction
- Dietitian: For individualised fibre and fluid counselling, particularly in patients with food insecurity, complex dietary needs, or comorbid conditions limiting fibre intake (e.g., gastroparesis, strictures)
- Pain medicine / Palliative care: For patients with opioid-induced constipation requiring complex laxative management and opioid dose optimisation
📚 References
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