A recent Tools for Practice1 reports that both tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs) may improve overall irritable bowel syndrome (IBS) symptoms. About 55% of patients treated with TCAs or SSRIs will benefit compared to ~35% with placebo.
Only TCAs improve abdominal pain for ~60% of patients compared to ~30% with placebo. TCA studies reported more side effects (drowsiness and dry mouth) than SSRIs. TCAs may work better for IBS-diarrhoea subtype, while SSRIs may work better for IBS-constipation subtype, but this has not been formally studied. Patients suspected of having IBS should have celiac disease ruled out.
Doses are generally on the low side e.g. TCAs starting at 10 mg and SSRI starting at 12.5 mg daily.
Psychological therapies may also be effective, but the evidence is less consistent.