Constipation

Constipation is one of the most common gastrointestinal complaints presenting in Australian primary care, affecting an estimated 14% of adults and up to 30% of children. It is characterised by infrequent bowel movements (typically <3 per week), straining, hard stools, incomplete evacuation, and/or the need for manual manoeuvres during defecation. While often considered a benign, self-limiting condition, chronic constipation significantly impairs quality of life, increases healthcare utilisation, and carries substantial economic costs estimated at over AUD 450 million annually in the Australian healthcare system.

The burden of constipation is not evenly distributed across the population. Prevalence is highest in women (approximately 2:1 female-to-male ratio), adults aged over 65 years, Aboriginal and Torres Strait Islander peoples, nursing home residents, and those with physical or intellectual disabilities. In children, functional constipation is the most common diagnosis, accounting for at least 95% of presentations, with a peak incidence during toilet training (ages 2–4 years).

A structured, evidence-based approach to diagnosis is essential. The Rome IV diagnostic criteria (2016) provide the international standard for functional constipation, while the Bristol Stool Form Scale remains a practical clinical tool. Australian general practitioners (GPs) play a central role in initial assessment, exclusion of secondary causes, medication review, and initiation of treatment. Escalation to gastroenterology or colorectal surgery is reserved for refractory cases, alarm features, or diagnostic uncertainty.

This guideline provides a comprehensive overview of the diagnostic model for constipation, common drug-related and secondary causes, evidence-based management of idiopathic constipation in adults, and the specific considerations for constipation in children. Recommendations are aligned with Australian Therapeutic Guidelines, the RACGP Red Book, NHMRC standards, and international consensus frameworks.

Australian Prevalence Data

A systematic diagnostic approach is essential to avoid the twin pitfalls of over-investigating simple functional constipation and missing serious secondary causes. The diagnostic model proceeds through four sequential steps: symptom characterisation using Rome IV criteria, structured history and medication review, targeted examination, and selective investigation.

Step 1: Symptom Characterisation — Rome IV Criteria

The Rome IV criteria for functional constipation require the presence of ≥2 of the following symptoms for at least 3 months, with symptom onset at least 6 months prior to diagnosis:

• Straining during >25% of defecations
• Lumpy or hard stools (Bristol Stool Form Scale types 1–2) in >25% of defecations
• Sensation of incomplete evacuation in >25% of defecations
• Sensation of anorectal obstruction/blockage in >25% of defecations
• Manual manoeuvres to facilitate >25% of defecations (e.g. digital evacuation, pelvic floor support)
• Fewer than 3 spontaneous bowel movements per week

Loose stools should rarely be present without the use of laxatives, and the patient should not meet criteria for irritable bowel syndrome (IBS). The Bristol Stool Form Scale is a validated tool freely available for use in Australian practice, classifying stool from type 1 (separate hard lumps) to type 7 (watery, no solid pieces).

Step 2: Structured History & Medication Review

A thorough history should cover onset and duration, stool frequency and consistency, associated symptoms (pain, bloating, nausea, mucus or blood per rectum), dietary fibre and fluid intake, physical activity level, toileting habits, psychological factors (anxiety, depression, history of abuse), and a complete medication review including over-the-counter and complementary medicines.

Step 3: Physical Examination

A focused examination should include abdominal palpation (masses, faecal loading, tenderness), digital rectal examination (DRE) to assess anal tone, stool consistency in the rectal vault, rectal masses, and assessment of perineal descent during simulated straining. DRE is recommended in all patients presenting with constipation and is particularly important in children to exclude anorectal malformations.

Step 4: Selective Investigation

Most patients with typical functional constipation and no alarm features do not require investigations beyond basic blood work. The following investigations are indicated when secondary causes are suspected or alarm features are present:

Diagnostic Algorithm Summary

Medication-induced constipation is among the most common and reversible causes encountered in Australian clinical practice. A thorough medication review — including prescription, over-the-counter, and complementary medicines — is a mandatory step before diagnosing idiopathic constipation. Secondary systemic causes must also be systematically excluded.

Common Drug Classes Causing Constipation

Opioid-Induced Constipation (OIC) — Specific Management

OIC affects 40–95% of patients prescribed opioids and is the most common opioid-related adverse effect. Unlike other forms of constipation, OIC does not develop tolerance and requires proactive management for the duration of opioid therapy.

Secondary Systemic Causes

Idiopathic (functional) constipation is diagnosed when no secondary structural, metabolic, or drug-related cause has been identified and Rome IV criteria are met. Management follows a stepwise approach from lifestyle modification through pharmacotherapy to specialist referral.

Step 1: Lifestyle & Dietary Modification

All patients with idiopathic constipation should receive counselling on the following measures, which form the foundation of treatment:

• Dietary fibre: Aim for 25–30 g/day. Increase gradually over 2–4 weeks to minimise bloating. Sources include wholegrain cereals, fruits (pears, prunes, kiwifruit), vegetables, legumes, and psyllium husk.
• Fluid intake: ≥1.5 L/day (6–8 glasses). Increased intake is particularly important when increasing fibre. In elderly and institutionalised patients, ensure assisted access to fluids.
• Physical activity: ≥150 minutes of moderate-intensity activity per week (walking, cycling). Even gentle daily walking improves bowel transit time.
• Toilet routine: Encourage a regular toileting schedule, ideally 15–30 minutes after meals (to exploit the gastrocolic reflex). Use a footstool to achieve a squatting position (knees above hips). Avoid straining — take time, relax, breathe.
• Kiwifruit: Two green kiwifruit daily has demonstrated efficacy comparable to psyllium in randomised trials and is recommended as a first-line dietary intervention in Australian practice.

Step 2: Pharmacotherapy — First-Line (Osmotic Laxatives)

Step 3: Pharmacotherapy — Second-Line (Stimulant Laxatives)

Stimulant laxatives are used when osmotic laxatives alone are insufficient, or as rescue therapy. They act by stimulating the myenteric plexus to increase intestinal motility and secretion. Short-term use is generally safe; chronic daily use should be avoided where possible, although evidence for the traditional concern about "cathartic colon" is weak.

Step 4: Pharmacotherapy — Third-Line & Specialist Agents

For patients refractory to combination osmotic and stimulant laxatives after ≥4–8 weeks of optimised therapy, specialist referral is recommended. The following agents are prescribed by or under guidance of gastroenterologists:

Biofeedback & Pelvic Floor Rehabilitation

For patients with demonstrated pelvic floor dyssynergia (anismus) — characterised by paradoxical contraction or failure to relax the puborectalis and external anal sphincter during attempted defecation — biofeedback therapy is the evidence-based treatment of choice. Multiple RCTs and a Cochrane review have demonstrated superiority over laxatives alone, with 60–80% of patients reporting improvement after 5–6 sessions. Biofeedback is available through specialist continence physiotherapy services at most major Australian hospitals and some community continence clinics.

Faecal Impaction Management

Faecal impaction (hard, immovable stool in the rectum causing overflow incontinence, abdominal pain, or urinary retention) requires a structured disimpaction regimen:

• Step 1: Oral macrogol 3350: 1–3 sachets daily (adult dose; higher doses for disimpaction)
• Step 2: Add stimulant laxative: senna 15–30 mg nocte or sodium picosulfate 10 mg nocte
• Step 3: Rectal bisacodyl suppository (10 mg PR) or glycerol suppository if oral agents are insufficient after 2–3 days
• Step 4: Phosphate or sodium citrate enemas (micro-enemas) — use cautiously in elderly and renal impairment
• Step 5: Manual evacuation under sedation — specialist/medical officer procedure for refractory impaction

Constipation Quick Reference — Stepwise Approach

Constipation accounts for 3–5% of all paediatric outpatient visits and up to 25% of paediatric gastroenterology referrals in Australia. Functional constipation is the cause in >95% of cases, with organic pathology (including Hirschsprung disease, hypothyroidism, coeliac disease, and anorectal malformation) comprising <5%.

Rome IV Criteria for Paediatric Functional Constipation

In children aged ≥4 years (with adequate verbal and toileting ability), ≥2 of the following criteria for at least 1 month:

• ≤2 defecations per week in the toilet
• At least 1 episode of faecal incontinence per week (after the acquisition of toileting skills)
• History of retentive posturing or excessive volitional stool retention
• History of painful or hard bowel movements
• Presence of a large faecal mass in the rectum
• History of large-diameter stools that may obstruct the toilet

In infants and children <4 years (or pre-verbal), the criteria include ≥2 of the above for 1 month, with the addition of irritability and decreased appetite that improve following passage of large stools, and the absence of criteria for Hirschsprung disease.

Paediatric Management — Disimpaction

If faecal impaction is present (palpable abdominal or rectal mass, overflow soiling), disimpaction must be achieved before commencing maintenance therapy. Macrogol 3350 is the recommended first-line agent for disimpaction in Australian children.

Paediatric Maintenance Therapy

Once disimpaction is achieved (or if impaction was not present), maintenance laxative therapy should commence immediately and continue for months to years (minimum 6 months is recommended). Abrupt cessation leads to relapse in >50% of children.

Behavioural & Psychological Interventions

Behavioural strategies are integral to paediatric constipation management, particularly in children with withholding behaviour and toilet avoidance:

• Toilet training reinforcement: Regular toileting (after meals), use of a footstool, praise and reward systems (sticker charts)
• Education: Explain the "poo that won't come out" cycle to parents and children using age-appropriate language
• Bowel diary: Record stool frequency, consistency (Bristol scale), laxative dose, and episodes of soiling — aids monitoring and dose titration
• Avoid punishment: Soiling is involuntary (overflow incontinence) and not deliberate; punitive responses worsen withholding and psychological distress
• Referral to child psychologist if significant anxiety, behavioural issues, or family distress

When to Refer — Paediatric

• Failure to respond to ≥3 months of optimised laxative therapy (adherent and adequate doses)
• Red flag features suggesting organic cause (see above)
• Suspected Hirschsprung disease — requires rectal biopsy (suction or full-thickness)
• Recurrent faecal impaction requiring repeated hospitalisation
• Need for anorectal manometry or colonic transit studies
• Significant psychological comorbidity or family dysfunction
• Consider coeliac screening (tTG-IgA) and thyroid function in refractory cases

Normal defecation requires coordinated colonic motility, adequate stool volume and consistency, intact anorectal sensation, and synchronised pelvic floor relaxation. Constipation results from disruption at one or more of these levels:

Normal Colonic Transit & Defecation Physiology

• Colonic motility: High-amplitude propagated contractions (HAPCs, or "mass movements") 1–3 times daily propel colonic contents caudally. These are most common post-prandially (gastrocolic reflex) and upon waking.
• Water absorption: The colon absorbs 1–1.5 L of fluid daily, converting liquid ileal effluent into semi-solid faeces. Excessive absorption (as with opioid use) produces hard, dry stool.
• Rectal filling & sampling: As stool enters the rectum, the recto-anal inhibitory reflex (RAIR) allows sampling by the anal mucosa to distinguish gas from solid. This is absent in Hirschsprung disease.
• Defecation: Voluntary process requiring: (1) conscious urge from rectal distension, (2) assumption of a sitting/squatting position, (3) Valsalva manoeuvre increasing intra-abdominal pressure, (4) relaxation of the puborectalis muscle and external anal sphincter, and (5) straightening of the anorectal angle.

Subtypes of Chronic Constipation

Understanding the subtype is important for directing therapy. Normal-transit constipation responds best to lifestyle measures and osmotic laxatives. Slow-transit constipation may require prokinetic agents (prucalopride) or, in severe refractory cases, surgical consideration (subtotal colectomy with ileorectal anastomosis — reserved for highly selected patients at tertiary centres). Pelvic floor dyssynergia responds to biofeedback therapy, which retrains coordinated defecation.

1. 1. Lacy BE, Mearin F, Chang L, et al. Bowel disorders. Gastroenterology. 2016;150(6):1393–1407.e5. (Rome IV criteria for functional constipation)
2. 2. Bharucha AE, Pemberton JH, Locke GR. American Gastroenterological Association technical review on constipation. Gastroenterology. 2013;144(1):218–238.
3. 3. National Institute for Health and Care Excellence (NICE). Constipation in children and young people: diagnosis and management. Clinical Guideline CG99. Updated 2017.
4. 4. Tabbers MM, DiLorenzo C, Berger MY, et al. Evaluation and treatment of functional constipation in infants and children: evidence-based recommendations from ESPGHAN and NASPGHAN. JPGN. 2014;58(2):258–274.
5. 5. Australian Institute of Health and Welfare (AIHW). Aboriginal and Torres Strait Islander Health Performance Framework 2023. Canberra: AIHW; 2023.
6. 6. Ford AC, Suares NC. Effect of laxatives and pharmacological therapies in chronic idiopathic constipation: systematic review and meta-analysis. Gut. 2011;60(2):209–218.
7. 7. Chey WD, Webster L, Sostek M, et al. Naloxegol for opioid-induced constipation in patients with noncancer pain. N Engl J Med. 2014;370(25):2387–2396.
8. 8. Belsey J, Greenfield S, Candy D, Geraint M. Systematic review: impact of constipation on quality of life in adults and children. Aliment Pharmacol Ther. 2010;31(9):938–944.
9. 9. Rao SS, Bharucha AE, Chiarioni G, et al. Anorectal disorders. Gastroenterology. 2016;150(6):1430–1442.e4. (Functional anorectal disorders — Rome IV)
10. 10. Royal Australian College of General Practitioners (RACGP). Guidelines for preventive activities in general practice (Red Book). 9th ed. Melbourne: RACGP; 2018.
11. 11. Gearry RB, Ware A, Withers T, et al. Green kiwifruit normalises bowel function in IBS patients: results from a multicentre randomised controlled trial. Am J Gastroenterol. 2023;118(1):157–166.
12. 12. National Health and Medical Research Council (NHMRC). Australian Dietary Guidelines. Canberra: NHMRC; 2013.
13. 13. Australian Commission on Safety and Quality in Health Care (ACSQHC). National Safety and Quality Health Service Standards. 2nd ed. Sydney: ACSQHC; 2021.
14. 14. Mugie SM, Benninga MA, Di Lorenzo C. Epidemiology of constipation in children and adults: a systematic review. Best Pract Res Clin Gastroenterol. 2011;25(1):3–18.
15. 15. Bassotti G, Villanacci V, Maurer CA, et al. The role of glial cells and apoptosis of enteric neurones in the neuropathology of intractable slow transit constipation. Gut. 2006;55(1):41–46.