Two weeks after L.K. starts nortriptyline 25 mg at bedtime, she reports significant relief from both

Two weeks after L.K. starts nortriptyline 25 mg at bedtime, she reports significant relief from both her abdominal pain and fatigue. She reports that she is sleeping better, and she now rates her pain as a 2 on a 1–10 scale. Her diarrhea has improved somewhat; however, she still suffers from a “diarrhea attack” before each presentation. What other treatments are available for IBS-D? What are the risks and benefits of these treatments?