What are the treatment options for irritable bowel syndrome (IBS)?

Treatment of Irritable Bowel Syndrome

Initial Management: Establish Diagnosis and Foundation

All patients with IBS should begin regular physical exercise immediately, as this provides significant benefits for global symptom management across all subtypes. 1

• Diagnose IBS using Rome criteria in patients under 45 years without alarm features (rectal bleeding, unintentional weight loss, family history of colon cancer, iron deficiency anemia, nocturnal symptoms) to avoid unnecessary testing that undermines patient confidence 1
• Explain IBS as a disorder of gut-brain interaction with a benign but relapsing-remitting course, introducing how diet, stress, and emotional responses affect the gut-brain axis 1
• Implement regular physical exercise for all IBS patients as foundational therapy before any other intervention 1, 2

First-Line Dietary Interventions

Start with targeted dietary counseling to identify and reduce excessive intake of lactose, fructose, sorbitol, caffeine, or alcohol. 1

• Begin soluble fiber (ispaghula/psyllium) at 3-4 g/day, gradually increasing to 25 g/day to avoid bloating 1, 2
• Avoid insoluble fiber (wheat bran) as it consistently worsens symptoms 1, 2
• Consider a supervised low FODMAP diet trial (10+ weeks for restriction and reintroduction phases) delivered by a trained dietitian only after 4 weeks of standard dietary advice fails 1, 3
• Trial probiotics for 12 weeks and discontinue if no improvement in global symptoms, bloating, or abdominal pain 1, 2

Pharmacological Treatment by Predominant Symptom Pattern

For Diarrhea-Predominant IBS (IBS-D)

Prescribe loperamide 4-12 mg daily (either regularly or prophylactically) as the most effective first-line treatment to reduce stool frequency, urgency, and fecal soiling. 1, 3

• Start loperamide at 2-4 mg up to four times daily, titrating to control symptoms while avoiding constipation 1, 3
• Consider rifaximin as second-line therapy if loperamide fails, though its effect on abdominal pain is limited 1, 2
• Trial cholestyramine specifically for patients with prior cholecystectomy or suspected bile acid malabsorption (approximately 10% of IBS-D patients) 1, 3
• For severe refractory IBS-D in women, alosetron (5-HT3 antagonist) 0.5 mg twice daily can be considered, but requires careful monitoring for ischemic colitis (0.2% incidence through 3 months) and constipation (29% incidence at 1 mg twice daily) 4

For Constipation-Predominant IBS (IBS-C)

Begin with polyethylene glycol (osmotic laxative), titrating dose according to symptoms, with abdominal pain being the most common side effect. 1, 2

• Use stimulant laxatives (senna, bisacodyl 10-15 mg daily) as first-line therapy based on efficacy in general constipation 1, 2
• Prescribe linaclotide (secretagogue) as the preferred second-line agent when first-line therapies fail after 4-6 weeks, as it is the most effective option for IBS-C with strong evidence 1, 2
• Lubiprostone is an alternative secretagogue if linaclotide is not tolerated 2
• Critical pitfall: Avoid anticholinergic antispasmodics (dicyclomine) in IBS-C as they reduce intestinal motility and worsen constipation 2

For Abdominal Pain (All Subtypes)

Start antispasmodics with anticholinergic properties (dicyclomine, hyoscine) for meal-exacerbated pain, though dry mouth, visual disturbance, and dizziness are common side effects. 1, 3

• Trial peppermint oil as an alternative antispasmodic with fewer side effects 1, 2, 3
• Antispasmodics are most effective when pain is triggered by meals 1, 3

Second-Line Neuromodulator Therapy

Initiate tricyclic antidepressants (amitriptyline 10 mg once daily at bedtime) for refractory pain and global symptoms, titrating slowly to 30-50 mg daily over at least 6 months if effective. 1, 2, 3

• TCAs are the most effective pharmacological treatment for mixed IBS and refractory pain across all subtypes 1, 2, 3
• Start at 10 mg nightly and increase by 10 mg weekly to minimize side effects 2, 3
• In IBS-C, use TCAs cautiously and ensure adequate laxative therapy is in place, as TCAs may worsen constipation 2
• Use selective serotonin reuptake inhibitors (SSRIs) as alternatives when TCAs are not tolerated or when concurrent mood disorder is present 1, 2, 3
• Low-dose TCAs target gastrointestinal symptoms, not psychological symptoms; if concurrent mood disorder exists, use SSRIs instead 3

Psychological Therapies for Refractory Cases

Refer for IBS-specific cognitive behavioral therapy or gut-directed hypnotherapy when symptoms persist despite 12 months of pharmacological treatment. 1, 2, 3

• These brain-gut behavior therapies are specifically designed for IBS and differ from psychological therapies that target depression and anxiety alone 3
• Consider mindfulness-based stress reduction (8-12 sessions) for patients with prominent psychological stress 1
• Biofeedback may be especially helpful for disordered defecation 3

Treatment Monitoring and Adjustment

Review treatment efficacy after 3 months and discontinue ineffective medications. 1, 3

• Continue TCAs for at least 6 months if the patient reports symptomatic improvement 1, 2
• Manage patient expectations by explaining that treatment aims for symptom relief and improved quality of life, not cure, as complete symptom resolution is often not achievable 1, 2

Critical Pitfalls to Avoid

Avoid opioids for chronic abdominal pain management due to risks of dependence, complications, and potential worsening of constipation. 1, 2

• Recognize frequent comorbidity with mental health disorders (anxiety, depression) and consider referral to gastropsychology when symptoms are moderate to severe and the patient accepts gut-brain dysregulation as a contributing factor 1, 3
• Do not recommend IgG antibody-based food elimination diets as they lack evidence and may lead to unnecessary dietary restrictions 2
• Do not recommend gluten-free diets unless celiac disease has been confirmed 2
• Avoid extensive testing once IBS diagnosis is established, as this undermines patient confidence 1, 3