#251 But I am not Depressed: Antidepressants for Irritable Bowel Syndrome
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- Tricyclic antidepressants (TCAs): 12 RCTs (787 patients) of amitriptyline, imipramine, desipramine, trimipramine, doxepin, and nortriptyline, versus placebo. Over 6-12 weeks:
- Global IBS symptom improvement: 57% TCA versus 36% placebo; number needed to treat (NNT)=5.
- Abdominal pain improvement: 59% TCA versus 28% placebo; NNT=4.
- Adverse Events (mostly drowsiness, dry mouth): 36% TCA versus 20% placebo; number needed to harm (NNH)=7.
- SSRIs: 7 RCTs (356 patients) of fluoxetine, paroxetine, and citalopram. Over 6-12 weeks:
- Global IBS symptom improvement: 55% SSRI versus 33% placebo; NNT=5.
- Abdominal pain improvement: 45% SSRI versus 26% placebo; not statistically different.
- Adverse events: 37% SSRI versus 27% placebo; not statistically different.
- Evidence limited by:
- Small sample sizes, short study duration, and likely publication bias.
- Adverse events not reported in all studies.
- Older systematic reviews show similar results.2,3
- Canadian guidelines recommend offering TCAs or SSRIs, irrespective of whether patients have depression or anxiety.4
- Up to 5 million adult Canadians may have symptoms compatible with IBS.5
- Indirectly, evidence for antidepressants in IBS appears stronger than antispasmodics,6 fiber,4 FODMAP diet,7 or probiotics.4
- TCAs may work better for IBS-diarrhea subtype, while SSRIs may work better for IBS-constipation subtype, but this has not been formally studied.4
- Patients suspected of having IBS should have celiac disease ruled-out.