What are the latest recommendations for managing irritable bowel syndrome (IBS)?

Management of Irritable Bowel Syndrome: Latest Evidence-Based Recommendations

Diagnosis: Make It Positive and Move Forward

Clinicians should make a positive diagnosis of IBS based on symptoms alone in patients under 45 years without alarm features, avoiding extensive testing that reinforces illness behavior and increases costs. 1

• Check only simple blood tests (complete blood count, C-reactive protein, celiac serology) and fecal calprotectin to exclude organic disease 1
• Alarm features requiring further investigation include: unintentional weight loss ≥5%, blood in stool, fever, anemia, nocturnal diarrhea, family history of colon cancer or inflammatory bowel disease, or age ≥50 years 1
• Colonoscopy has no role in typical IBS except when alarm features are present or in IBS-D patients with risk factors for microscopic colitis (female sex, age ≥50, autoimmune disease, recent NSAID/PPI use) 1
• For IBS-D with atypical features (nocturnal diarrhea, prior cholecystectomy), test for bile acid malabsorption with SeHCAT scanning or serum 7α-hydroxy-4-cholesten-3-one 1

Patient Education: Set Realistic Expectations

Explain IBS as a disorder of gut-brain interaction with a benign but relapsing/remitting course, emphasizing that treatment aims to improve—not eliminate—symptoms. 1, 2

• Address the patient's specific concerns and beliefs about their condition directly 1
• Use a symptom diary to identify triggers and track response to interventions 1
• Avoid reinforcing abnormal illness behavior through repeated testing once diagnosis is established 1

First-Line Management: Lifestyle and Dietary Modifications

Exercise (Universal Recommendation)

All patients with IBS should engage in regular physical activity, which provides significant symptom benefits. 1, 2

Dietary Interventions (Stepwise Approach)

Start with traditional dietary advice as the most cost-effective and patient-friendly first-line approach. 3

• Traditional dietary advice includes: regular meal patterns, adequate hydration, limiting caffeine and alcohol, reducing intake of fatty/spicy foods, and identifying personal trigger foods 1
• For fiber modification: Use soluble fiber (ispaghula/psyllium) starting at 3-4 g/day and gradually increasing for IBS-C, but avoid insoluble fiber (wheat bran) which worsens bloating 1, 2
• Avoid IgG-based food allergy testing—it has no role in IBS management 1

If traditional dietary advice fails after 4-8 weeks, refer to a trained dietitian for a supervised low FODMAP diet delivered in three phases: restriction (4-6 weeks), reintroduction, and personalization. 1, 2, 4

• The low FODMAP diet is effective but more expensive, time-consuming, and difficult to follow when eating out compared to traditional dietary advice 3
• A gluten-free diet is not recommended as it shows no superiority over traditional dietary advice 1, 3

Probiotics

Consider a 12-week trial of probiotics for global symptoms and bloating, discontinuing if no improvement occurs. 1, 2

• No specific strain or species can be recommended due to inconsistent evidence 1

Pharmacological Management: Symptom-Targeted Approach

For Abdominal Pain and Cramping

Use antispasmodics (dicyclomine, hyoscine) as first-line therapy for meal-related abdominal pain. 1, 2

• Peppermint oil is an alternative antispasmodic option 2, 5
• Common side effects include dry mouth, visual disturbance, and dizziness 1

For IBS-D (Diarrhea-Predominant)

Loperamide 4-12 mg daily (either regularly or prophylactically before going out) is the first-line agent for reducing stool frequency and urgency. 1, 2

• Titrate dose carefully to avoid abdominal pain, bloating, nausea, and constipation 1
• Rifaximin 550 mg three times daily for 14 days is FDA-approved for IBS-D and improves both abdominal pain and stool consistency with the most favorable safety profile among approved agents 6, 7
• Rifaximin can be repeated if symptoms recur (median time to recurrence is 10 weeks) 6
• Consider bile acid sequestrants (cholestyramine) specifically for patients with bile acid malabsorption, though it is often less well tolerated than loperamide 1

For IBS-C (Constipation-Predominant)

Increase soluble fiber supplementation (ispaghula/psyllium) starting at 3-4 g/day and gradually increasing. 1, 2

• If laxatives fail, offer linaclotide as second-line therapy 8

For Mixed IBS (IBS-M) or Refractory Pain

Tricyclic antidepressants (TCAs) are the most effective first-line pharmacological treatment for global symptoms and abdominal pain in mixed IBS. 1, 2

• Start amitriptyline 10 mg once daily at bedtime and titrate slowly to 30-50 mg once daily 1, 2
• Provide careful explanation that TCAs are used as gut-brain neuromodulators, not for depression 1
• TCAs are particularly useful when insomnia is prominent but may worsen constipation 1
• If concurrent mood disorder exists, use SSRIs instead of low-dose TCAs 2
• Continue TCAs for at least 6 months if symptomatic improvement occurs 2

Psychological Therapies: For Refractory Cases

Consider IBS-specific cognitive behavioral therapy or gut-directed hypnotherapy when symptoms persist despite pharmacological treatment for 12 months. 1, 2, 8

• These brain-gut behavioral therapies are specifically designed for IBS and differ from psychological therapies targeting depression/anxiety alone 2
• Refer to a gastropsychologist if symptoms are moderate-to-severe and the patient accepts that symptoms relate to gut-brain dysregulation 2
• Initial psychological interventions include explanation, reassurance, and simple relaxation therapy 1
• Biofeedback may be particularly helpful for disordered defecation 1

Referral to Gastroenterology

Refer to secondary care when there is diagnostic doubt, severe or refractory symptoms despite first-line treatments, or patient request for specialist opinion. 1

Critical Pitfalls to Avoid

• Do not pursue colonoscopy or extensive testing in typical IBS without alarm features—this reinforces illness behavior and increases healthcare costs 1
• Do not recommend IgG-based food allergy testing—true food allergy is rare in IBS 1, 2
• Do not use insoluble fiber (wheat bran) as it worsens bloating and abdominal pain 1, 2
• Do not implement a low FODMAP diet without dietitian supervision—it risks nutritional deficits and is unnecessarily restrictive without proper reintroduction phases 1, 2
• Do not start TCAs at standard antidepressant doses—begin at 10 mg and titrate slowly to avoid side effects and improve tolerability 1, 2

Treatment Algorithm Summary

1. Diagnosis: Positive diagnosis based on symptoms in patients <45 without alarm features 1
2. First-line (all patients): Regular exercise + traditional dietary advice 1, 2, 3
3. Symptom-specific first-line pharmacotherapy:
   • Pain: Antispasmodics 1, 2
   • IBS-D: Loperamide or rifaximin 1, 6
   • IBS-C: Soluble fiber 1, 2
4. Second-line dietary: Low FODMAP diet with dietitian supervision 1, 2
5. Second-line pharmacotherapy: TCAs (amitriptyline 10-50 mg) for refractory pain or mixed symptoms 1, 2
6. Refractory cases (>12 months): IBS-specific cognitive behavioral therapy or gut-directed hypnotherapy 1, 2