📋 Key Information Summary
- Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disorder characterised by recurrent abdominal pain associated with altered bowel habits, affecting approximately 10–15% of Australians.
- Diagnosis is clinical using the Rome IV criteria: recurrent abdominal pain ≥1 day/week in the last 3 months, related to defecation, associated with change in stool frequency or form; symptom onset ≥6 months before diagnosis.
- Subtype using the Bristol Stool Form Scale: IBS-C (≥25% Bristol 1–2), IBS-D (≥25% Bristol 6–7), IBS-M (both), IBS-U (unclassified).
- A limited diagnostic workup is recommended in the absence of alarm features: FBC, CRP or faecal calprotectin, coeliac serology (especially in IBS-D/IBS-M), and TSH where indicated.
- Alarm features requiring urgent investigation include rectal bleeding, unintentional weight loss, iron-deficiency anaemia, nocturnal symptoms, family history of colorectal cancer or IBD, and onset after age 50.
- First-line dietary management includes a monash FODMAP-guided elimination diet (2–6 weeks) followed by structured reintroduction under dietitian supervision; soluble fibre (psyllium) is recommended over insoluble fibre.
- Lifestyle interventions — regular moderate exercise, stress reduction, adequate sleep — have Level A evidence for symptom improvement in IBS.
- Pharmacotherapy is subtype-directed: antispasmodics (hyoscine, mebeverine, peppermint oil) for pain; laxatives (osmotic preferred) for IBS-C; loperamide for IBS-D; low-dose TCAs or SSRIs for refractory symptoms.
- Rifaximin (PBS Authority Required) is an option for IBS-D failing conventional therapy; eluxadoline and linaclotide are available but may have restricted PBS access.
- Gut-directed psychological therapies (CBT, gut-directed hypnotherapy) are effective for moderate–severe IBS and should be offered early, not as a last resort.
- Referral to gastroenterology is indicated for alarm features, diagnostic uncertainty, IBS-M with predominant bloody diarrhoea, or failure to respond to 6–12 months of optimised management.
- Aboriginal and Torres Strait Islander Australians have higher rates of functional GI symptoms and face barriers to specialist and dietitian access; culturally safe, community-based approaches are essential.
Introduction & Australian Epidemiology
Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder (FGID) worldwide, defined by the Rome IV criteria as a disorder of gut–brain interaction. It is characterised by recurrent abdominal pain associated with defecation or a change in bowel habits, in the absence of structural or biochemical abnormalities that would explain the symptoms.
In Australia, population-based surveys estimate a prevalence of 10–15% using Rome IV criteria, with approximately 30% of those affected seeking medical care. IBS accounts for a substantial proportion of gastroenterology outpatient referrals and primary care consultations. The condition is more prevalent in women (female-to-male ratio approximately 2:1), with peak onset between ages 20 and 40 years.
The economic burden is significant: direct healthcare costs (GP visits, investigations, medications) combined with indirect costs (absenteeism, reduced productivity) are estimated at over AUD 1 billion annually. Patients with IBS report quality-of-life impairment comparable to diabetes mellitus and chronic kidney disease.
Australian data: The 2022 AIHW National Health Survey identified functional GI symptoms in approximately 12% of adults, with higher rates in those aged 25–44, women, and individuals reporting high psychological distress. Aboriginal and Torres Strait Islander Australians report functional GI symptoms at approximately 1.5 times the rate of non-Indigenous Australians.
IBS significantly impacts on primary care utilisation. The Royal Australian College of General Practitioners (RACGP) recommends a positive diagnostic strategy — making a symptom-based diagnosis and initiating management — rather than pursuing exhaustive exclusionary investigations, provided alarm features are absent.
Rome IV Criteria & Subtyping
The Rome IV criteria (2016) represent the international consensus for diagnosing IBS. A positive diagnosis based on symptom criteria has a sensitivity of approximately 65% and specificity of 98% for organic GI disease when alarm features are absent.
Rome IV Diagnostic Criteria for IBS
Recurrent abdominal pain, on average, ≥1 day per week in the last 3 months, associated with two or more of the following:
- Related to defecation (may be improved or worsened by defecation)
- Associated with a change in stool frequency
- Associated with a change in stool form (appearance)
Criteria fulfilled for the last 3 months with symptom onset ≥6 months before diagnosis.
Rome IV vs Rome III: Rome IV changed "discomfort" to "pain" and modified the frequency threshold from "at least 3 days/month" to "≥1 day/week." This resulted in a slightly lower prevalence estimate and a population with more severe symptoms.
IBS Subtypes by Bristol Stool Form Scale
Subtyping is based on the predominant stool pattern on days with abnormal bowel movements, using the Bristol Stool Form Scale (BSFS). Patients should be subtyped at each clinical encounter as the pattern may change over time.
| Subtype | Abbreviation | Bristol Type | Proportion of Days | Prevalence |
|---|---|---|---|---|
| IBS with predominant constipation | IBS-C | Type 1–2 (hard/lumpy) | ≥25% of bowel movements | ~30% |
| IBS with predominant diarrhoea | IBS-D | Type 6–7 (loose/watery) | ≥25% of bowel movements | ~35% |
| IBS with mixed bowel habits | IBS-M | Type 1–2 on ≥25% and Type 6–7 on ≥25% | Both criteria met | ~25% |
| IBS unclassified | IBS-U | Insufficient abnormality of stool consistency | Neither C nor D criteria met | ~10% |
Distinguishing IBS from Other FGIDs
Functional dyspepsia, functional constipation, and functional diarrhoea overlap considerably with IBS. The Rome IV framework acknowledges that up to 40% of patients with IBS meet criteria for at least one other FGID. Key distinctions:
- Functional constipation: Difficult, infrequent stools without significant abdominal pain — pain is the defining feature that separates IBS-C from functional constipation.
- Functional diarrhoea: Loose stools without pain — distinguishing feature from IBS-D.
- Microscopic colitis: Must be considered in older women with IBS-D-like symptoms; requires colonic biopsies to exclude.
Limited Diagnostic Workup
A positive diagnostic approach — diagnosing IBS based on symptom criteria and a limited set of investigations — is recommended over an exhaustive exclusionary workup. Studies demonstrate that extensive investigation rarely identifies organic disease in patients meeting Rome IV criteria without alarm features, and repeated negative testing increases health anxiety.
Alarm Features Requiring Further Investigation
Red-flag features — investigate urgently (colonoscopy, CT abdomen/pelvis, specialist referral):
- Rectal bleeding or melaena not explained by haemorrhoids
- Unintentional weight loss >5% over 6 months
- Iron-deficiency anaemia (ferritin <30 µg/L, low MCV)
- Nocturnal symptoms that wake the patient from sleep
- Family history of colorectal cancer, coeliac disease, or inflammatory bowel disease
- New onset of symptoms in a patient aged ≥50 years
- Progressive worsening of symptoms over weeks to months
- Palpable abdominal mass or lymphadenopathy
Recommended Baseline Investigations
Essential
Full blood count (FBC)
Screen for anaemia (iron deficiency), raised WCC (infection/inflammation). MBS Item 66512.
Essential
C-reactive protein (CRP)
Normal CRP (<5 mg/L) in the absence of alarm features strongly supports IBS over IBD. MBS Item 66547.
Available
Faecal calprotectin
High negative predictive value for IBD (<50 µg/g effectively excludes active IBD). Preferred over CRP in IBS-D. MBS Item 66579 — available in most Australian pathology labs.
Essential
Coeliac serology (tTG-IgA + total IgA)
Recommended in all IBS-D and IBS-M patients. Prevalence of coeliac disease is ~1% in the general population and 4–5% in IBS cohorts. MBS Item 66832. Patient must be on a gluten-containing diet.
Available
Thyroid function tests (TSH ± fT4)
Consider in IBS-D or mixed subtype, or if symptoms are atypical. MBS Item 66715.
Available
Faecal microscopy, culture, and sensitivity
Consider in acute-onset IBS-D, travel history, or foodborne illness risk. Exclude Giardia antigen (MBS Item 69320).
Optional / Specialist-Level Investigations
- Hydrogen breath testing: For suspected small intestinal bacterial overgrowth (SIBO) or lactose/fructose malabsorption. Available at select centres; MBS items vary by state. Not routinely recommended for IBS diagnosis.
- Colonoscopy: Indicated only with alarm features or age ≥50 with new-onset symptoms (bowel cancer screening age). Bulk-billed via National Bowel Cancer Screening Program if age 50–74.
- Upper GI endoscopy: Consider if prominent upper abdominal symptoms, suspected coeliac disease (with positive serology), or refractory dyspepsia.
- SeHCAT scan: For suspected bile acid malabsorption (BAM) in IBS-D — available at limited tertiary centres in Australia (MBS Item 61339). BAM accounts for up to 25% of IBS-D cases.
Positive Diagnosis Approach — Summary
1
Symptom Assessment
Apply Rome IV criteria. Use Bristol Stool Form Scale to subtype. Screen for alarm features.
2
Baseline Labs
FBC, CRP or faecal calprotectin, coeliac serology (IBS-D/M), ± TSH.
3
Positive Diagnosis
If Rome IV met + no alarm features + labs normal → diagnose IBS. Explain the diagnosis confidently.
4
Initiate Management
Begin dietary, lifestyle, and pharmacologic interventions based on subtype. Reassess at 6–8 weeks.
Dietary & Lifestyle Management
Dietary and lifestyle interventions form the foundation of IBS management. Up to 70% of patients report that food triggers their symptoms. A structured, dietitian-guided approach is recommended over self-directed restriction, which risks nutritional deficiency and disordered eating.
Low FODMAP Diet
The low FODMAP (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, And Polyols) diet was developed at Monash University and is the most evidence-based dietary intervention for IBS. It has Level A evidence from multiple randomised controlled trials.
Monash University FODMAP resources: The Monash University FODMAP app (iOS/Android, ~AUD 13) provides traffic-light ratings for foods based on laboratory-analysed FODMAP content. Recommend this tool to all patients undertaking dietary modification. Referral to a FODMAP-trained dietitian (find via Dietitians Australia) is strongly recommended.
Three-Phase FODMAP Protocol
- Elimination phase (2–6 weeks): Restrict all high-FODMAP foods. Assess response — approximately 50–75% of patients experience meaningful symptom improvement. If no improvement after 6 weeks, FODMAP is unlikely to be the primary driver; proceed to other interventions.
- Reintroduction phase (6–8 weeks): Systematically reintroduce each FODMAP subgroup one at a time, in increasing doses, over 3 days. Identify individual triggers and tolerance thresholds.
- Personalisation phase (ongoing): Liberalise the diet to include all tolerated foods. Goal is the least restrictive diet that maintains symptom control. Long-term strict low FODMAP is not recommended due to risks of reduced microbiome diversity and nutritional inadequacy.
Caution: The low FODMAP diet is not a first-line self-management tool. Improperly implemented restriction diets may worsen food anxiety and contribute to disordered eating. Always involve an accredited practising dietitian (APD) with FODMAP training.
Fibre Supplementation
- Soluble fibre (psyllium/ispaghula husk): Recommended as first-line for all IBS subtypes. Start at 3–5 g daily, titrate up to 10–12 g over several weeks. Evidence supports improvement in global IBS symptoms and stool consistency. Available OTC (Metamucil®, Fybogel®).
- Insoluble fibre (wheat bran): Not recommended in IBS — may worsen bloating, flatulence, and abdominal pain. Avoid or use with caution.
- Partially hydrolysed guar gum (PHGG): Emerging evidence supports use in IBS-C and IBS-M. 5 g daily. Available as Sunfiber® in Australia.
Lifestyle Interventions
Evidence Level A
Exercise
150 min/week moderate-intensity physical activity (brisk walking, cycling, swimming). RCT evidence demonstrates significant improvement in IBS symptom severity scores. Reduces visceral hypersensitivity and improves gut transit.
All subtypes
Evidence Level A
Stress Reduction
Mindfulness-based stress reduction (MBSR), yoga, progressive muscle relaxation. Stress is a well-established trigger for IBS flares via the gut–brain axis. Recommend apps such as Smiling Mind (free, Australian).
All subtypes
Evidence Level B
Sleep Hygiene
Address sleep disturbance, which affects up to 50% of IBS patients and correlates with symptom severity. Consistent sleep schedule, limiting caffeine after midday, screen-time reduction before bed.
All subtypes
Other Dietary Considerations
- Gluten-free diet: May benefit a subset of patients (non-coeliac gluten/wheat sensitivity) even with negative coeliac serology. Trial of 4–6 weeks after excluding coeliac disease; evidence is moderate.
- Caffeine and alcohol: Advise moderation. Both exacerbate visceral motility and sensitivity. Limit caffeine to ≤2 cups/day.
- Probiotics: Evidence is strain-specific. Bifidobacterium infantis 35624 and Lactobacillus plantarum 299v have the strongest evidence. Trials of individual strains for 4–8 weeks are reasonable. Multi-strain preparations of uncertain benefit. Not PBS-listed.
Pharmacologic Management
Pharmacotherapy in IBS is adjunctive to dietary and lifestyle interventions and should be tailored to the predominant symptom and subtype. Medications should be trialled for a minimum of 4–8 weeks at adequate dose before declaring failure. Polypharmacy should be avoided.
Symptom-Based: Abdominal Pain & Cramping
Hyoscine butylbromide
Buscopan® · Antispasmodic (antimuscarinic)
Adult dose
10–20 mg PO up to QID PRN; max 80 mg/day
Paediatric dose
6–12 years: 10 mg PO TDS PRN; <6 years: not recommended
Route
Oral
Renal adjustment
No specific adjustment; caution in severe renal impairment
Key side effects
Dry mouth, blurred vision, urinary retention (avoid in glaucoma, prostatic hypertrophy)
PBS status
✔ PBS General Benefit
Mebeverine
Colofac® · Antispasmodic (direct smooth muscle relaxant)
Adult dose
135 mg PO TDS, 20 min before meals; or 200 mg SR BD
Paediatric dose
Not recommended <10 years; 10–14 years: 135 mg PO TDS
Route
Oral
Renal / Hepatic
No specific adjustment
Key side effects
Well tolerated; rare allergic reactions
PBS status
✔ PBS General Benefit
Peppermint oil (enteric-coated)
Colpermin® · Antispasmodic (calcium channel blockade)
Adult dose
1–2 capsules (0.2 mL each) PO TDS, 30 min before meals; max 8 weeks continuous
Paediatric dose
≥8 years: dose as per adult; <8 years: not recommended
Route
Oral (enteric-coated capsules — do not crush)
Key side effects
Heartburn (take before meals), anal burning if not enteric-coated. Avoid in GERD/hiatus hernia.
PBS status
✘ Not PBS-listed (OTC, ~AUD 15–20)
Subtype-Specific: IBS-C (Constipation Predominant)
Macrogol 3350 (polyethylene glycol)
Movicol® · Osmotic laxative
Adult dose
1–3 sachets daily; dissolve in 125 mL water per sachet. Titrate to effect.
Paediatric dose
1 sachet daily for age 2–6; 2 sachets daily for age 6–12 (for constipation)
Route
Oral
Renal adjustment
Caution in renal impairment — risk of electrolyte disturbance
PBS status
✔ PBS General Benefit
Linaclotide
Constella® · Guanylate cyclase-C agonist
Adult dose
290 µg PO OD, 30 min before breakfast
Paediatric dose
Not established for <18 years
Route
Oral
Renal / Hepatic
No adjustment required
Key side effects
Diarrhoea (most common, ~20%); contraindicated in mechanical bowel obstruction
PBS status
⚠ PBS Authority Required — IBS-C with inadequate response to ≥2 laxatives over ≥3 months
Subtype-Specific: IBS-D (Diarrhoea Predominant)
Loperamide
Imodium® · µ-opioid receptor agonist
Adult dose
2–4 mg PO after each loose stool; maintenance 2–6 mg/day in divided doses; max 16 mg/day
Paediatric dose
Not recommended <12 years for IBS
Route
Oral
Renal / Hepatic
Use with caution in hepatic impairment
Key side effects
Constipation, abdominal cramping, nausea. Contraindicated in acute dysentery or suspected obstruction.
PBS status
✔ PBS General Benefit
Rifaximin
Xifaxan® · Non-absorbable antibiotic
Adult dose
550 mg PO TDS for 14 days; may repeat course if symptoms recur
Paediatric dose
Not established for IBS in children
Route
Oral
Renal / Hepatic
Avoid in severe hepatic impairment (Child-Pugh C)
Key side effects
Generally well tolerated; nausea, headache, flatulence. Minimal systemic absorption.
PBS status
⚠ PBS Authority Required — IBS-D with inadequate response to loperamide ± antispasmodics and ≥3 months of dietary modification
Eluxadoline
Viberzi® · Mixed µ-opioid receptor agonist / δ-opioid antagonist
Adult dose
100 mg PO BD with food (75 mg if ALT elevation or if co-prescribed with OATP1B inhibitors)
Paediatric dose
Not indicated <18 years
Route
Oral
Renal / Hepatic
Contraindicated in severe hepatic impairment, pancreatitis history, cholecystectomy (no gallbladder), alcohol abuse (>3 drinks/day), biliary obstruction
Key side effects
Nausea, constipation, abdominal pain. Rare pancreatitis — discontinue if severe upper abdominal pain.
PBS status
⚠ PBS Authority Required — specialist initiation only
Gut-Directed Antidepressants
Low-dose neuromodulators are effective in IBS at doses lower than those used for depression. They modulate visceral pain perception, central pain processing, and gut motility. Allow 6–8 weeks for full effect.
Amitriptyline
Endep® · Tricyclic antidepressant (TCA)
Adult dose
Start 5–10 mg PO nocte; titrate by 5–10 mg every 2–4 weeks to target 25–50 mg nocte; max 75 mg
Best for
IBS-D (slows transit), pain, sleep disturbance
Renal / Hepatic
Reduce dose in hepatic impairment; use with caution in renal impairment
Key side effects
Anticholinergic effects (dry mouth, constipation, urinary retention), sedation, weight gain. Avoid in cardiac conduction disease.
PBS status
✔ PBS General Benefit (for depression indication; IBS use is off-label)
Escitalopram
Lexapro® · Selective serotonin reuptake inhibitor (SSRI)
Adult dose
Start 5 mg PO OD; increase to 10 mg OD after 1–2 weeks if tolerated
Best for
IBS-C (may improve transit), comorbid anxiety/depression
Renal / Hepatic
Max 10 mg in hepatic impairment; no renal adjustment
Key side effects
Nausea, headache, sexual dysfunction. Avoid with MAOIs. Caution: serotonin syndrome risk.
PBS status
✔ PBS General Benefit
Bile Acid Sequestrants (IBS-D with Suspected BAM)
Cholestyramine
Questran® · Bile acid sequestrant
Adult dose
4 g PO OD–BD; increase to 4 g TDS if required
Route
Oral (mix sachet with water or juice)
Key side effects
Constipation, bloating, nausea. May impair absorption of fat-soluble vitamins and other medications (give other drugs 1 hour before or 4 hours after).
PBS status
✔ PBS General Benefit
Subtype-Specific: IBS-M (Mixed Bowel Habits)
IBS-M is the most challenging subtype to treat pharmacologically as patients alternate between constipation and diarrhoea. Management principles include:
- Target the currently predominant symptom at each visit
- Antispasmodics and gut-directed antidepressants (especially TCAs) are preferred as they address pain without exacerbating bowel habit abnormalities
- Avoid antidiarrhoeals (may worsen constipation phases) and stimulant laxatives (may worsen diarrhoea phases)
- Soluble fibre (psyllium) is particularly useful as it normalises stool form in both directions
- Low-dose TCAs are often the single most useful medication in IBS-M
Quick Reference: Medication by Subtype
IBS-C
Psyllium → Macrogol → Linaclotide (PBS Auth) ± SSRI
Ongoing
Add antispasmodic PRN for pain
IBS-D
Loperamide PRN → Peppermint oil ± TCA → Rifaximin (PBS Auth) ± Cholestyramine
4–8 wk per agent
Consider SeHCAT for suspected BAM
IBS-M
Psyllium + Antispasmodic → Low-dose TCA
Ongoing
Treat predominant symptom at each visit
All subtypes (pain)
Hyoscine / Mebeverine / Peppermint oil PRN
PRN
Antispasmodics before meals
Psychological Therapies & Referral
The gut–brain axis is central to IBS pathophysiology. Psychological comorbidity (anxiety, depression, somatisation) is present in up to 60% of patients with IBS seen in specialist practice. Psychological therapies have Level A evidence and should be presented as a treatment modality, not a stigmatising suggestion that symptoms are "psychological."
Evidence-Based Psychological Therapies
Strongest Evidence
Gut-Directed CBT
Targets maladaptive cognitions about GI symptoms, catastrophising, and avoidance behaviours. Delivered by clinical psychologists with GI experience. 6–12 sessions. NNT of approximately 4 for symptom improvement. Now available via telehealth through programs such as Mindgut (Monash University).
Moderate–severe IBS; comorbid anxiety
Strong Evidence
Gut-Directed Hypnotherapy
Targets visceral sensitivity and autonomic dysfunction via hypnotic suggestion and gut-focused imagery. 6–12 sessions. Manchester or North Carolina protocols. Approximately 70–80% response rate. Available at some tertiary GI centres (e.g., Royal Adelaide Hospital, Monash). Digital programs (Nerva app, Mindset) emerging as accessible alternatives.
Moderate–severe IBS; refractory symptoms
Good Evidence
Other Approaches
Acceptance and Commitment Therapy (ACT), mindfulness-based therapy for IBS (MBT-IBS), psychodynamic psychotherapy. Access may be limited in regional/rural Australia. Digital therapeutics and online programs may bridge the gap.
Patient preference; specialist availability
Medicare Better Access Initiative: Patients with IBS and comorbid mental health conditions may be eligible for up to 20 sessions per calendar year under a Mental Health Treatment Plan (MHTP, MBS Item 721 + 80000–80015). This provides a Medicare rebate for sessions with a registered psychologist, including those trained in gut-directed therapies.
When to Refer
Refer to gastroenterology if any of the following are present:
- Alarm features (rectal bleeding, weight loss, iron-deficiency anaemia, nocturnal symptoms, age ≥50 with new symptoms, family history of CRC/IBD)
- Diagnostic uncertainty — atypical symptoms, incomplete Rome IV criteria, positive faecal calprotectin or CRP
- Failure to respond to 6–12 months of optimised first- and second-line management
- IBS-M with predominant bloody diarrhoea (exclude microscopic colitis, bile acid malabsorption)
- Severe symptoms with significant functional impairment (unable to work, social isolation)
- Patient request for specialist opinion
Access to Psychological Therapies for IBS in Australia
| Therapy | Availability | How to Access | Cost |
|---|---|---|---|
| Gut-directed CBT (face-to-face) | Metropolitan centres; some regional via telehealth | MHTP + psychologist referral; Ask for GI-experienced psychologist | Gap varies (~AUD 50–150/session) |
| Gut-directed hypnotherapy | Limited — select tertiary hospitals and private practitioners | Gastroenterologist or GP referral | Variable; some hospital-based = no cost |
| Digital hypnotherapy (Nerva app) | Australia-wide (online) | Self-enrol or GP-prescribed | ~AUD 120 for 6-week programme |
| Monash Mindgut (CBT via telehealth) | Australia-wide | Research program; check availability | May be free during research phases |
The Therapeutic Relationship
A strong GP–patient relationship is the most important factor in IBS management. Validating the patient's symptoms, explaining the pathophysiology (disordered gut–brain signalling, not "all in your head"), and setting realistic expectations (symptom management rather than cure) improve adherence and outcomes. The RACGP recommends regular follow-up (every 4–8 weeks during active management) to reinforce positive strategies and adjust treatment.
Special Populations
Pregnancy & Breastfeeding
Hyoscine butylbromide
Limited data; avoid in first trimester if possible. May be used short-term if benefit outweighs risk.
Mebeverine
Limited human data; avoid unless clearly needed.
Psyllium (soluble fibre)
Safe in pregnancy and breastfeeding. First-line for constipation management.
Macrogol 3350
Safe in pregnancy; first-line osmotic laxative.
Loperamide
Generally considered safe; short-term use acceptable. Avoid in first trimester if possible.
Amitriptyline
Avoid if possible, especially first trimester. Discuss risk–benefit. Compatible with breastfeeding at low doses.
Linaclotide, Rifaximin, Eluxadoline
Insufficient data in pregnancy. Avoid. Use alternative approaches.
Paediatrics
- Paediatric IBS affects 5–10% of children and is diagnosed using modified Rome IV criteria. Functional abdominal pain — not otherwise specified (FAP-NOS) should be distinguished.
- First-line: dietary modification (fibre, identify triggers), parental reassurance, normal school attendance. Low FODMAP in children should only be undertaken with paediatric dietitian supervision.
- Pharmacotherapy evidence is limited in children. Peppermint oil (enteric-coated, ≥8 years) and psyllium have the best evidence. Avoid TCAs in children without specialist guidance.
- Psychological interventions (CBT, guided imagery, gut-directed hypnotherapy) have strong evidence in paediatric functional GI disorders. Refer to paediatric psychologist.
- Referral to paediatric gastroenterology if alarm features, diagnostic uncertainty, or failure to respond to 3–6 months of management.
Elderly (≥65 years)
- New-onset IBS symptoms in patients aged ≥50 years mandate investigation (colonoscopy) to exclude colorectal cancer, diverticular disease, and microscopic colitis before accepting an IBS diagnosis.
- IBS is less common in elderly patients; consider medication-related GI symptoms (metformin, NSAIDs, PPIs, SSRIs, antibiotics).
- Anticholinergic medications (hyoscine) should be used cautiously due to risk of confusion, urinary retention, falls, and constipation. Mebeverine is preferred.
- Loperamide use with caution — risk of megacolon if there is subclinical obstruction.
- Low-dose TCAs: increased risk of cardiac conduction abnormalities, falls, and cognitive impairment. ECG before starting. Consider SSRI as alternative.
Renal Impairment
- Macrogol 3350: use with caution in CKD — monitor electrolytes (hyponatraemia, hypokalaemia). Avoid in patients on fluid restriction.
- Amitriptyline: no specific dose adjustment, but enhanced sensitivity in uraemia. Start low, go slow.
- Linaclotide: no dose adjustment required.
- Loperamide: no specific adjustment; minimal renal excretion.
Hepatic Impairment
- Rifaximin: avoid in Child-Pugh C (severe) hepatic impairment.
- Eluxadoline: contraindicated in severe hepatic impairment. ALT monitoring recommended.
- Escitalopram: maximum 10 mg/day in hepatic impairment.
- Amitriptyline: reduce dose; use caution.
- Loperamide: use with caution — reduced first-pass metabolism.
Aboriginal and Torres Strait Islander Health
📚 References
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