What are the treatment options for a patient with Irritable Bowel Syndrome (IBS)?

Treatment of Irritable Bowel Syndrome

Begin with soluble fiber (ispaghula/psyllium) 3-4 g/day, gradually increasing to 25 g/day, combined with regular physical exercise as foundational therapy for all IBS patients, then add symptom-specific pharmacological treatments based on the predominant bowel pattern. 1

Initial Management Framework

• Establish a positive diagnosis using Rome criteria without extensive testing in patients under 45 years without alarm features (weight loss, rectal bleeding, anemia, family history of colon cancer), as unnecessary investigations undermine patient confidence and increase healthcare costs 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 this provides significant benefits for global symptom management 1

First-Line Dietary Interventions

• Start soluble fiber (ispaghula/psyllium) at 3-4 g/day, gradually increasing to 25 g/day to avoid bloating, as this is effective for global symptoms and abdominal pain 1
• Avoid insoluble fiber (wheat bran) as it consistently worsens IBS symptoms 1
• Provide initial dietary counseling focusing on identifying and reducing excessive intake of lactose (>280 ml milk/day), fructose, sorbitol, caffeine, or alcohol 2, 1
• 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 1, 3
• Trial probiotics for 12 weeks and discontinue if no improvement in global symptoms, bloating, or abdominal pain, though no specific strain can be recommended 1

Pharmacological Treatment by Predominant Bowel 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
• Consider rifaximin 550 mg three times daily for 14 days as second-line therapy, though its effect on abdominal pain is limited 1, 4
• Trial cholestyramine for patients with prior cholecystectomy or suspected bile acid malabsorption (approximately 10% of IBS-D patients) 1
• Consider eluxadoline as an FDA-approved option for adults with IBS-D 5

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 or bisacodyl 10-15 mg daily) as first-line therapy, recognizing limited specific evidence in IBS-C but reasonable based on efficacy in general constipation 1
• Prescribe linaclotide 290 mcg once daily on an empty stomach as the preferred second-line agent when first-line therapies fail after 4-6 weeks, as it is the most effective FDA-approved option for IBS-C with strong evidence for both abdominal pain and constipation 1, 6
• Consider plecanatide or lubiprostone 8 mcg twice daily as alternative secretagogues if linaclotide is not tolerated, though lubiprostone has higher rates of nausea 1, 6

For Abdominal Pain (All Subtypes)

• Start antispasmodics with anticholinergic properties (dicyclomine 10-20 mg three to four times daily, hyoscine) for meal-exacerbated pain, though dry mouth, visual disturbance, and dizziness are common side effects 1
• Avoid anticholinergic antispasmodics in IBS-C patients as they reduce intestinal motility and enhance water reabsorption, which will worsen constipation 1
• Trial peppermint oil as an alternative antispasmodic with fewer side effects 1, 2

Second-Line Neuromodulator Therapy for Refractory Pain

• Initiate tricyclic antidepressants (amitriptyline 10 mg once daily at bedtime) for refractory pain and global symptoms, titrating slowly by 10 mg/week to 30-50 mg daily over at least 6 months if effective 1, 2
• Use selective serotonin reuptake inhibitors (SSRIs) at therapeutic doses as alternatives when TCAs are not tolerated or when concurrent mood disorder is present 1, 2
• Consider selective noradrenaline reuptake inhibitors (SNRIs) for patients with IBS and psychological comorbidity, particularly those with chronic painful disorders 2

Important caveat: TCAs may worsen constipation in IBS-C patients through anticholinergic effects, so ensure adequate laxative therapy is in place before initiating 1

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
• Consider mindfulness-based stress reduction (8-12 sessions) for patients with prominent psychological stress and negative emotion 1
• Dynamic psychotherapy may be beneficial for patients who relate symptom exacerbations to stressors, have associated anxiety or depression, or have symptoms of relatively short duration 2

The evidence shows hypnotherapy is time-consuming and expensive but cost-effective in severe refractory cases, with success rates of 61-66% and greater efficacy in younger patients without serious psychopathology 2

Treatment Monitoring and Adjustment

• Review treatment efficacy after 3 months and discontinue ineffective medications 1
• Continue TCAs for at least 6 months if the patient reports symptomatic improvement 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 1

Critical Pitfalls to Avoid

• Avoid opioids for chronic abdominal pain management due to risks of dependence, complications, and potential worsening of constipation 1
• Do not recommend IgG antibody-based food elimination diets as they lack evidence and may lead to unnecessary dietary restrictions 1
• Do not recommend a gluten-free diet unless celiac disease has been confirmed 1
• 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, 2
• Avoid continuing ineffective therapies indefinitely, such as docusate (Colace), which lacks efficacy for constipation 1

Integrated Care Model

The most effective approach combines dietary modification, pharmacological treatment, and psychological interventions as equal partners rather than sequential steps. 3 This integrated care model offers the greatest likelihood for success, particularly for patients with moderate to severe symptoms or psychological comorbidity 2, 3

For patients with substantial coexisting psychological symptoms, consider the Mediterranean diet alongside brain-gut behavioral therapy, as this addresses both gastrointestinal and psychological components simultaneously 2