What is the best treatment for Irritable Bowel Syndrome (IBS) with constipation and bloating?

Best Treatment for IBS with Constipation and Bloating

Start with soluble fiber (ispaghula/psyllium) at 3-4 g/day, gradually increased to avoid worsening bloating, combined with regular exercise and dietary modifications to reduce gas-producing foods, lactose, fructose, and sorbitol. 1, 2

First-Line Dietary and Lifestyle Approach

Immediate Dietary Modifications

• Reduce or eliminate insoluble fiber (wheat bran) as it consistently worsens bloating in IBS-C patients 1
• Identify and limit excessive intake of lactose (>280 ml milk/day), fructose, and sorbitol, which are common bloating triggers 3, 1
• Avoid gas-producing foods and excessive caffeine to minimize bloating symptoms 1
• Keep a 2-week symptom and food diary to identify specific aggravating factors 3

Soluble Fiber as Foundation

• Begin with soluble fiber (ispaghula/psyllium) at 3-4 g/day for both constipation and abdominal pain 1, 2
• Increase the dose very gradually to prevent exacerbating bloating 1, 2
• This addresses constipation without worsening bloating when titrated properly 2

Exercise Recommendation

• Prescribe regular physical exercise to all IBS-C patients as foundational therapy for global symptom improvement 2

Second-Line: Low FODMAP Diet

If simple dietary measures fail after 4-6 weeks, implement a low FODMAP diet under supervision of a qualified dietitian 1, 2

• This diet is more restrictive and difficult to implement, requiring professional supervision 1
• It effectively reduces both bloating and abdominal pain 1
• Must include planned reintroduction of foods according to tolerance 2
• Never use IgG antibody-based food elimination diets as they lack evidence and lead to unnecessary restrictions 1, 4

Pharmacological Treatment for Bloating and Pain

Antispasmodics for Bloating with Pain

• Peppermint oil is the preferred first-line antispasmodic option for bloating and abdominal pain 1, 2
• Anticholinergic antispasmodics (dicyclomine) can be effective for bloating associated with abdominal pain, but cause dry mouth, visual disturbances, and dizziness 1, 4
• Critical caveat: Anticholinergic antispasmodics may worsen constipation, so use cautiously in IBS-C 4

Probiotics

• Trial a probiotic for 12 weeks for global symptoms and bloating 1, 2
• No specific strain can be recommended based on current evidence 1, 2
• Discontinue if no improvement occurs after 12 weeks 1

Treatment for Persistent Constipation

Osmotic Laxatives

• Start polyethylene glycol (PEG) for constipation, titrating the dose according to symptoms 4
• Abdominal pain is the most common side effect 4

Secretagogues for Refractory Constipation

• Linaclotide is the most effective second-line agent when first-line therapies fail, with the added benefit of direct analgesic effects 2, 5
• Linaclotide 290 mcg once daily is FDA-approved for IBS-C and improves both constipation and abdominal pain 5
• Lubiprostone is an alternative if linaclotide is not tolerated 2, 6
• Lubiprostone 8 mcg twice daily is FDA-approved for IBS-C in women ≥18 years old 6

Treatment for Refractory Pain Despite Above Measures

If abdominal pain persists after 3-6 weeks of antispasmodics, initiate tricyclic antidepressants (TCAs) as second-line therapy 2, 4

• Start amitriptyline 10 mg once daily at bedtime 2, 4
• Titrate slowly (by 10 mg/week) to 30-50 mg once daily 2, 4
• Critical warning: TCAs may worsen constipation, so ensure adequate laxative therapy is in place before starting 2, 4
• Continue for at least 6 months if symptomatic response occurs 4
• Review efficacy after 3 months and discontinue if no response 4

Alternative Neuromodulator

• Selective serotonin reuptake inhibitors (SSRIs) can be considered if TCAs are not tolerated or worsen constipation 2, 4

Psychological Therapies for Persistent Symptoms

When symptoms persist despite 12 months of pharmacological treatment, implement cognitive-behavioral therapy (CBT) specific for IBS or gut-directed hypnotherapy 1, 2, 4

• Both CBT and hypnotherapy are effective for reducing bloating and abdominal pain 1, 2
• These should be considered early, not just after multiple drug failures 2

Common Pitfalls to Avoid

• Never prescribe anticholinergic antispasmodics like dicyclomine for IBS-C without considering that they can worsen constipation 4
• Never recommend gluten-free diets unless celiac disease has been confirmed 1, 4
• Never use opioids for chronic abdominal pain management due to dependence risks 1
• Recognize that bloating responds poorly to medications alone, making dietary measures the priority 3, 1
• Manage patient expectations: complete symptom resolution is often not achievable; the goal is symptom relief and improved quality of life 4