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

Treatment of Irritable Bowel Syndrome

Begin with lifestyle modifications and dietary interventions as first-line therapy, followed by symptom-specific pharmacological treatment based on the predominant IBS subtype (diarrhea, constipation, or mixed), with tricyclic antidepressants reserved for refractory abdominal pain. 1, 2

First-Line Approach: Lifestyle and Dietary Modifications

• Recommend regular physical exercise to all IBS patients as this provides significant benefits for symptom management and should be the foundation of treatment. 1, 2

• Provide dietary counseling to identify and reduce excessive intake of lactose, fructose, sorbitol, caffeine, or alcohol, particularly in patients with diarrhea-predominant symptoms. 1

• Start soluble fiber (ispaghula/psyllium) at 3-4 g/day, gradually increasing to avoid bloating, which is effective for global symptoms and abdominal pain in IBS-C. 1, 2

• Avoid insoluble fiber (wheat bran) as it consistently worsens IBS symptoms. 2

• Consider a low FODMAP diet as second-line dietary therapy for patients with persistent symptoms after 4-6 weeks of first-line interventions, but this must be supervised by a trained dietitian with planned reintroduction of foods according to tolerance. 1, 2

• Trial probiotics for 12 weeks for global symptoms and abdominal pain, discontinuing if no improvement occurs, though no specific strain can be recommended. 1, 2

Symptom-Specific Pharmacological Treatment

For IBS with Diarrhea (IBS-D)

• Loperamide at doses of 4-12 mg daily is the most effective first-line pharmacological treatment for IBS-D, significantly reducing stool frequency and urgency. 3, 1

• Loperamide can be used prophylactically when diarrhea is anticipated (e.g., before going out), with divided doses or a single 4 mg dose at night both showing effectiveness. 3

• Codeine (15-30 mg, 1-3 times daily) is an alternative for diarrhea but carries higher risk of sedation and drug dependency. 3, 1

• Consider cholestyramine for the approximately 10% of IBS-D patients who have bile salt malabsorption, particularly those with prior cholecystectomy or <5% retention on SeHCAT testing. 3, 1

• Rifaximin (550 mg three times daily for 14 days) is an effective second-line treatment for global IBS-D symptoms and can be used for up to two additional retreatment courses. 4, 5, 6

• Eluxadoline is an effective second-line agent for IBS-D but has several drug-drug interactions and contraindications that limit its use as initial therapy. 5, 7

For IBS with Constipation (IBS-C)

• Start polyethylene glycol (osmotic laxative) for constipation, titrating the dose according to symptoms, with abdominal pain being the most common side effect. 2

• Linaclotide is the most effective secretagogue available for IBS-C and should be the preferred second-line agent when first-line therapies fail. 2, 8

• Lubiprostone (8 mcg twice daily for IBS-C in women ≥18 years) is an alternative secretagogue if linaclotide is not tolerated. 2, 9

• Take lubiprostone with food and water to reduce nausea, and swallow capsules whole without breaking or chewing. 9

For IBS with Mixed Symptoms (IBS-M)

• Tricyclic antidepressants are the most effective first-line pharmacological treatment for mixed IBS, starting with amitriptyline 10 mg once daily at bedtime and gradually titrating to 30-50 mg daily. 2

• Antispasmodics with anticholinergic properties (such as dicyclomine) can be effective for abdominal pain, though dry mouth, visual disturbance, and dizziness are common side effects. 3, 2

Treatment for Refractory Abdominal Pain

• Tricyclic antidepressants are the most effective drugs for treating refractory IBS pain, initially at low doses (10 mg amitriptyline at bedtime), but occasionally higher doses (30-50 mg) may be required. 3, 1, 2

• TCAs work through multiple mechanisms including modifying gut motility and altering visceral nerve responses, with effects occurring long before any mood changes. 3

• Avoid TCAs if constipation is a major feature, as they may worsen this symptom. 3, 2

• Continue TCAs for at least 6 months if the patient reports symptomatic response. 2

• Selective serotonin reuptake inhibitors (SSRIs) may be considered as second-line neuromodulators when TCAs are not tolerated or worsen constipation. 1, 2

Antispasmodics for Pain

• Antispasmodics with anticholinergic action (such as dicyclomine) are slightly more effective than direct smooth muscle relaxants for reducing abdominal pain. 3, 1

• Peppermint oil can be useful as an antispasmodic for abdominal pain. 2

• Common side effects of anticholinergic antispasmodics include dry mouth, which may limit their use. 3

Psychological Therapies for Persistent Symptoms

• Consider IBS-specific cognitive behavioral therapy or gut-directed hypnotherapy for patients with symptoms refractory to pharmacological treatment for 12 months. 1, 2

• Psychological therapies are particularly beneficial for patients who relate symptom exacerbations to stressors, have associated anxiety or depression, or have symptoms of relatively short duration. 2

• Simple relaxation therapy may be beneficial as an initial approach before more intensive psychological interventions. 1

Critical Management Principles

• Explain the diagnosis of IBS as a disorder of gut-brain interaction, including a simple explanation of the gut-brain axis and how it is affected by diet, stress, and cognitive/emotional responses to symptoms. 2

• Review treatment efficacy after 3 months and discontinue ineffective medications to avoid polypharmacy and reinforcement of illness behavior. 1, 2

• Avoid extensive testing once IBS diagnosis is established, as this can reinforce abnormal illness behavior and prevent patients from dealing effectively with underlying psychological problems. 3, 2

• Recognize that symptoms may relapse and remit over time, requiring periodic adjustment of treatment strategy rather than expecting complete cure. 1, 2

Common Pitfalls to Avoid

• 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 prescribing medications that may be counterproductive in patients with major psychological problems, as this may reinforce abnormal illness behavior. 3

• Be aware that the initial placebo response in IBS is high but wears off with time, causing repeated consultations. 3