What are the treatment options for chronic abdominal pain?

Treatment of Chronic Abdominal Pain

For chronic abdominal pain, initiate treatment with antispasmodics for meal-related pain or low-dose tricyclic antidepressants (starting at 10 mg amitriptyline nightly, titrating to 30-50 mg) for frequent or severe pain, while avoiding opioids entirely due to risk of narcotic bowel syndrome and increased mortality. 1, 2

Severity-Based Treatment Algorithm

Mild Symptoms

• Start with education, reassurance, and non-prescription interventions for patients with minimal functional impairment 1
• Soluble fiber (ispaghula 3-4 g/day, gradually increased) improves global symptoms and abdominal pain, but avoid insoluble fiber like wheat bran which worsens symptoms 1
• Antispasmodics (dicyclomine, hyoscine) are effective first-line agents, particularly when pain is meal-related, though anticholinergic side effects (dry mouth, visual disturbance, dizziness) are common 1
• Peppermint oil serves as an alternative first-line option with fewer side effects 1

Moderate Symptoms with Functional Impairment

Second-line pharmacological treatment:

• Tricyclic antidepressants are the most effective drugs for chronic abdominal pain based on meta-analysis showing superiority over placebo and SSRIs 1, 2
• Begin amitriptyline 10 mg at bedtime, titrate slowly to 30-50 mg daily over several weeks 1, 2
• TCAs work as "gut-brain neuromodulators" with analgesic effects independent of mood improvement, requiring 1-3 weeks for pain relief but causing side effects within days 2
• Avoid TCAs if constipation is a major feature; consider SSRIs as an alternative, though they are less effective for pain 1

For diarrhea-predominant pain:

• 5-HT3 receptor antagonists (ondansetron 4-8 mg three times daily) are the most efficacious agents for IBS with diarrhea, though constipation is a common side effect 1
• Rifaximin 550 mg three times daily for 14 days improves abdominal pain and stool consistency in IBS-D, with 38% achieving combined response versus 31% with placebo 1, 3
• Eluxadoline is effective but contraindicated in patients with prior cholecystectomy, sphincter of Oddi problems, alcohol dependence, pancreatitis, or severe liver impairment 1

For constipation-predominant pain:

• Linaclotide and other secretagogues improve both pain and constipation through cyclic GMP production that attenuates visceral pain 1

Severe or Refractory Symptoms

Escalation strategy:

• Consider combination neuromodulators (augmentation therapy) such as duloxetine plus gabapentin, which are more efficacious than monotherapy for severe chronic continuous abdominal pain 1
• Monitor vigilantly for serotonin syndrome (fever, hyperreflexia, tremor, sweating, diarrhea) when combining SSRIs and SNRIs 1
• Refer to multidisciplinary pain center for integrated care involving gastroenterology, pain management, and mental health services 1, 2

Psychological Interventions

Initiate when symptoms impair quality of life:

• Cognitive-behavioral therapy, gut-directed hypnotherapy, and dynamic psychotherapy reduce abdominal pain and diarrhea (but not constipation) 1, 2
• CBT is most effective for patients who relate symptom exacerbations to stressors, have anxiety/depression, or have symptoms of relatively short duration 1
• Hypnosis, stress management, and relaxation techniques improve pain through changes in GI physiology, improved coping, or altered interpretation of gut signals 1
• Breathing techniques and relaxation training can be taught by gastroenterologists immediately to address autonomic arousal 2

Dietary Modifications

• Low FODMAP diet supervised by a trained dietitian is effective as second-line therapy, with gradual reintroduction according to tolerance 1, 2
• Avoid food elimination diets based on IgG antibodies as they lack evidence 1
• Gluten-free diets are not recommended for chronic abdominal pain 1
• Probiotics may help for up to 12 weeks, but no specific species or strain can be recommended; discontinue if no improvement 1

Critical Medication Avoidances

Never prescribe opioids for chronic functional abdominal pain:

• Opioids cause narcotic bowel syndrome (occurring in 6% of chronic users), characterized by paradoxical worsening pain with escalating doses 4, 2
• Opioids increase risks of dependence, gut dysmotility, serious infection, and mortality 2
• Conventional analgesia including opiates is not a successful strategy for IBS pain 1

Use NSAIDs with extreme caution:

• NSAIDs should be considered rarely and only after safer therapies fail in elderly patients 4
• NSAIDs are contraindicated in active peptic ulcer disease, chronic kidney disease, and heart failure 4

Special Considerations

For abdominal wall pain:

• Carnett's sign (pain worsening with abdominal wall tensing) identifies abdominal wall pain rather than visceral pain 5
• Trigger point injections, lidocaine patches, and activity modification are effective for this commonly overlooked cause 4, 5

For patients with psychological comorbidity:

• Screen explicitly for intimate partner violence, trauma, and abuse, as these predict worse outcomes and accelerate transition to chronic pain 2
• SSRIs at therapeutic doses are preferred over low-dose TCAs when treating concurrent mood disorders, as low TCA doses are inadequate for depression 1

Common Pitfalls to Avoid

• Avoid repetitive testing once functional diagnosis is established, as this increases costs without benefit and reinforces illness behavior 2
• Do not exceed 4 grams daily acetaminophen when combining sources, particularly with opioid combination agents 4
• Never dismiss pain as "functional" without appropriate evaluation and targeted treatment 4
• Avoid language suggesting patients "shouldn't be in so much pain"; validate that both GI and psychological symptoms are real 2
• Do not prescribe antispasmodics as a class; individual agents vary dramatically in efficacy and safety 6