Treatment for Irritable Bowel Syndrome
First-Line Treatment: Start with Lifestyle and Dietary Modifications
All patients with IBS should begin with regular physical exercise and soluble fiber supplementation (ispaghula/psyllium 3-4 g/day, gradually increased), while avoiding insoluble fiber like wheat bran which worsens symptoms. 1, 2
Core First-Line Interventions
Regular physical exercise is strongly recommended for all IBS patients as foundational therapy, improving global symptoms regardless of subtype 1, 2
Soluble fiber (ispaghula/psyllium) should be started at 3-4 g/day and built up gradually to avoid bloating and gas—this is effective for both global symptoms and abdominal pain 1, 2
Avoid insoluble fiber (wheat bran) as it consistently exacerbates symptoms, particularly bloating and discomfort 1, 2
Reduce intake of caffeine, alcohol, spicy foods, and high-fat meals, which commonly trigger symptoms 3, 4
Maintain regular meal patterns and ensure adequate hydration as part of general healthy eating advice 3
Second-Line Dietary Approach
Low FODMAP diet should be considered when symptoms persist after 4-6 weeks of first-line dietary measures, but must be supervised by a trained dietitian with planned reintroduction of foods according to tolerance 1, 2
Do NOT recommend IgG antibody-based food elimination diets—these lack evidence and lead to unnecessary dietary restrictions 1, 2
Do NOT recommend gluten-free diets unless celiac disease has been confirmed 1, 2
Probiotics as Adjunctive Therapy
- Probiotics may be effective for global symptoms and abdominal pain—advise a 12-week trial and discontinue if no improvement occurs, though no specific strain can be recommended 1, 2
Pharmacological Treatment: Target the Predominant Symptom
For IBS with Diarrhea (IBS-D)
Loperamide (2-4 mg up to four times daily) is first-line for reducing stool frequency, urgency, and fecal soiling, though it must be titrated carefully to avoid abdominal pain, bloating, and constipation 1, 2
Antispasmodics (particularly those with anticholinergic properties like dicyclomine) are effective for abdominal pain, especially when symptoms are meal-related, though dry mouth, visual disturbance, and dizziness are common side effects 1, 2
Peppermint oil can be useful as an alternative antispasmodic with fewer side effects 1, 2
For IBS with Constipation (IBS-C)
Start with soluble fiber (ispaghula/psyllium) at 3-4 g/day, gradually increased 1, 2
If fiber fails after 4-6 weeks, add polyethylene glycol (PEG) as an osmotic laxative, titrating the dose according to symptoms 2
If PEG is insufficient, add bisacodyl 10-15 mg once daily as a stimulant laxative, with a goal of one non-forced bowel movement every 1-2 days 2
For refractory IBS-C, prescribe linaclotide 290 mcg once daily on an empty stomach as the preferred second-line agent—this addresses both abdominal pain and constipation with strong evidence 2
CRITICAL PITFALL: Do NOT prescribe anticholinergic antispasmodics like dicyclomine for IBS-C, as they reduce intestinal motility and worsen constipation 2
For IBS with Mixed Pattern (IBS-M)
Tricyclic antidepressants (TCAs) are the most effective first-line pharmacological treatment for IBS-M—start with amitriptyline 10 mg once daily at bedtime and titrate slowly to 30-50 mg daily 2
Antispasmodics can be used for abdominal pain episodes 2
Loperamide can be used as needed for diarrhea episodes 2
Second-Line Treatment: Neuromodulators for Refractory Symptoms
Tricyclic antidepressants (TCAs) are the most effective second-line treatment for global symptoms and abdominal pain when first-line therapies fail. 1, 2
Start amitriptyline 10 mg once daily at bedtime, titrate slowly (by 10 mg/week) to 30-50 mg daily 1, 2
Explain the rationale clearly: TCAs work through pain modulation via the gut-brain axis, not for depression—this improves treatment acceptance 2
Continue for at least 6 months if the patient reports symptomatic improvement 1, 2
Review efficacy after 3 months and discontinue if no response 1, 2
SSRIs may be effective as an alternative when TCAs are not tolerated, though evidence is weaker 1, 2
Third-Line Treatment: Psychological Therapies for Persistent Symptoms
IBS-specific cognitive behavioral therapy (CBT) and gut-directed hypnotherapy should be considered when symptoms persist despite 12 months of pharmacological treatment 1, 2
These therapies have demonstrated efficacy for global symptoms, abdominal pain, and quality of life 1, 2
Critical Pitfalls to Avoid
Do NOT perform extensive investigations once IBS diagnosis is established in patients under 45 without alarm features—this undermines confidence in the diagnosis 1, 2
Do NOT use opioids for chronic abdominal pain management due to risks of dependence and complications 2
Do NOT continue ineffective therapies indefinitely—reassess at 3 months and discontinue if no benefit 1, 2
Do NOT prescribe anticholinergic antispasmodics for IBS-C as they worsen constipation 2
Recognize the substantial placebo response (approximately 50%) which can give a false impression of initial treatment efficacy 2
Treatment Monitoring and Patient Education
Establish a positive diagnosis based on symptoms (Rome criteria) in the absence of alarm features, and explain clearly that IBS is a disorder of gut-brain interaction with a benign but relapsing/remitting course 1, 2
Address specific patient fears directly, particularly concerns about cancer or serious disease—this therapeutic relationship forms the foundation of successful management 2
Use a symptom diary to help identify triggers and guide treatment choices 2
Manage expectations realistically: complete symptom resolution is often not achievable—the goal is symptom relief and improved quality of life, not cure 2