Tricyclic Antidepressants (e.g. amitriptyline (Elavil), desipramine (Norpramin), nortriptyline (Pamelor))

How it works: Acts on nerves within the gastrointestinal tract, spinal cord, and brain to improve abdominal and bowel symptoms.

Which symptoms does it help: Overall IBS symptoms including the abdominal pain. TCAs can also slow down the gut transit and improve symptoms of diarrhea.  

How long it takes to see a benefit: 2-4 weeks.

FDA approved: N/A

Dosage: 10-75 mg, Initiate at low dose and increase the dose based on response and tolerability every couple of weeks.

Special considerations or risks: Dosage for IBS are usually lower than anti-depressive range. When discontinuing TCAs, gradually taper the dose over 2 to 4 weeks to minimize withdrawal symptoms.

Most common side effects: Drowsiness, dry mouth, palpitations, blurred vision, and weight gain.

Recommendation: ACG recommends TCAs for overall symptom improvement in IBS patients.