What are the recommended medications for treating abdominal pain?

Medication for Abdominal Pain

For abdominal pain, start with antispasmodics or peppermint oil as first-line therapy, and if inadequate, escalate to low-dose tricyclic antidepressants (e.g., amitriptyline 10 mg at bedtime, titrated to 30-50 mg) as second-line treatment. 1

First-Line Pharmacological Approach

Antispasmodics

• Antispasmodics are effective for global symptoms and abdominal pain, though the evidence quality is very low 1
• Anticholinergic agents (dicyclomine, hyoscine) show slightly better efficacy than direct smooth muscle relaxants (mebeverine) 1
• Common side effects include dry mouth, visual disturbance, and dizziness, which may limit tolerability 1
• These medications work particularly well when symptoms are exacerbated by meals 1

Peppermint Oil

• Peppermint oil is safe and effective for relief of abdominal pain and global IBS symptoms 1
• This represents a well-tolerated first-line option with minimal side effects 1

Soluble Fiber

• Soluble fiber (ispaghula) effectively treats global symptoms and abdominal pain with strong recommendation and moderate evidence quality 1
• Start at low dose (3-4 g/day) and build up gradually to avoid bloating 1
• Avoid insoluble fiber (wheat bran) as it may exacerbate symptoms 1

Second-Line Pharmacological Approach

Tricyclic Antidepressants (TCAs)

• TCAs are the most effective second-line drugs for global symptoms and abdominal pain, with strong recommendation and moderate evidence quality 1
• Start at low dose (10 mg amitriptyline once daily at bedtime) and titrate slowly to maximum 30-50 mg once daily 1
• TCAs should be the first choice for abdominal pain among neuromodulators based on meta-analysis showing significant benefit over placebo 1
• Mechanism involves gut-brain neuromodulation, altering pain perception and central processing 1
• Careful explanation of rationale is required, as patients may be concerned about taking "antidepressants" for gut symptoms 1
• Side effects include constipation (which may be beneficial in diarrhea-predominant conditions), dry mouth, and sedation 1

Selective Serotonin Reuptake Inhibitors (SSRIs)

• SSRIs are an alternative second-line option if TCAs are ineffective or not tolerated, though evidence is weaker (weak recommendation, low quality evidence) 1
• Consider SSRIs as first choice if mood disorder is suspected, as therapeutic doses are needed for psychiatric symptoms 1
• Evidence shows possible improvement but with less certainty than TCAs 1

Important Caveats and Pitfalls

What NOT to Use

• Conventional analgesia, including opiates, is not a successful strategy for treatment of abdominal pain in functional disorders 1
• NSAIDs like ibuprofen are not recommended for chronic abdominal pain and carry significant GI risks including ulceration, bleeding, and perforation 2
• Acetaminophen may be used for acute pain but lacks evidence for chronic functional abdominal pain 3, 4

Context-Specific Considerations

For IBS with Diarrhea:

• Loperamide (4-12 mg daily) effectively reduces diarrhea but has limited effect on abdominal pain 1
• 5-HT3 receptor antagonists (ondansetron 4-8 mg, titrated) are highly efficacious second-line options 1
• Rifaximin is efficacious but has limited effect on abdominal pain specifically 1

For IBS with Constipation:

• Linaclotide is the most efficacious secretagogue (strong recommendation, high quality evidence) 1
• Lubiprostone causes less diarrhea but nausea is common 1

Dosing and Duration

• Neuromodulators require at least 6 months of treatment in responders 1
• First-line treatments should be continued for 4+ weeks before assessing response 1
• Probiotics may be tried for up to 12 weeks and discontinued if no improvement 1

Patient Communication

• Explain that neuromodulators work on gut-brain pathways, not just mood 1
• Set realistic expectations: complete symptom resolution is often not achievable 1
• Emphasize that drug treatment is one component of multimodal management 1