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

Treatment of Irritable Bowel Syndrome

Begin with lifestyle modifications and dietary interventions, followed by symptom-targeted pharmacotherapy, reserving psychological therapies for refractory cases after 12 months of failed medical management. 1, 2

Initial Management and Patient Education

• Establish a positive diagnosis using Rome criteria without extensive testing in patients under 45 years without alarm features, avoiding unnecessary investigations that undermine patient confidence 2
• Explain IBS as a disorder of gut-brain interaction with a benign but relapsing-remitting course, introducing the concept of how diet, stress, and emotional responses affect the gut-brain axis 3, 1
• Implement regular physical exercise for all IBS patients as this provides significant benefits for global symptom management 1, 4

First-Line Dietary Interventions

• Provide initial dietary counseling focusing on identifying and reducing excessive intake of lactose, fructose, sorbitol, caffeine, or alcohol 2, 4
• Start soluble fiber (ispaghula/psyllium) at 3-4 g/day, gradually increasing to 25 g/day to avoid bloating, while avoiding insoluble fiber (wheat bran) which worsens symptoms 1, 2
• Consider a supervised low FODMAP diet trial (10+ weeks for restriction and reintroduction phases) delivered by a trained dietitian for patients with persistent symptoms after 4 weeks of standard dietary advice 3, 1, 2
• 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, 2, 4
• Use alosetron (5-HT3 antagonist) 0.5-1 mg twice daily as second-line therapy for women with severe IBS-D, noting that 43-51% achieve moderate to substantial improvement versus 31% with placebo 5
• Critical warning: Alosetron carries risk of ischemic colitis (0.2% through 3 months) and serious constipation complications; discontinue immediately if rectal bleeding, bloody diarrhea, or new/worsening abdominal pain occurs 5
• Consider rifaximin as second-line therapy, though its effect on abdominal pain is limited 3, 1
• Trial cholestyramine for patients with prior cholecystectomy or suspected bile acid malabsorption (approximately 10% of IBS-D patients) 2, 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
• Use stimulant laxatives (senna) as first-line therapy, recognizing limited specific evidence in IBS-C but reasonable based on efficacy in general constipation 3
• 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
• Consider plecanatide or lubiprostone as alternative secretagogues if linaclotide is not tolerated 3, 1

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 3, 1, 2
• Trial peppermint oil as an alternative antispasmodic with fewer side effects 3, 1

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 3, 1, 2
• TCAs are the most effective pharmacological treatment for mixed IBS and pain-predominant symptoms across all subtypes 1, 2
• Use caution with TCAs in IBS-C as they may worsen constipation; ensure adequate laxative therapy is in place 1
• Consider selective serotonin reuptake inhibitors (SSRIs) as alternatives when TCAs are not tolerated or when concurrent mood disorder is present 3, 1, 2

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 3, 1, 2, 4
• These brain-gut behavior therapies are specifically designed for IBS and differ from standard psychological therapies targeting depression and anxiety alone 2
• Consider mindfulness-based stress reduction (8-12 sessions) for patients with prominent psychological stress and negative emotion 3

Treatment Monitoring and Adjustment

• Review treatment efficacy after 3 months and discontinue ineffective medications 1, 2
• Continue TCAs for at least 6 months if the patient reports symptomatic improvement 3, 1
• Recognize that complete symptom resolution is often not achievable; manage patient expectations by explaining that treatment aims for symptom relief and improved quality of life, not cure 3, 1

Critical Pitfalls to Avoid

• Do not recommend IgG antibody-based food elimination diets as they lack evidence and may lead to unnecessary dietary restrictions 1, 2
• Do not recommend gluten-free diets unless celiac disease has been confirmed 1, 2
• Avoid opioids for chronic abdominal pain management due to risks of dependence, complications, and potential worsening of constipation 3
• Do not perform extensive testing once IBS diagnosis is established, as this undermines patient confidence and increases healthcare costs 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 3, 2