Alosetron (Lotronex)

How it works: Acts on specific serotonin receptors targeting nerves in the intestinal tract. These nerves can sense pain and are responsible for bowel function.

Which symptoms does it help: Overall IBS symptoms, abdominal pain, diarrhea.

How long it takes to see a benefit: Within one week.

FDA approved: Women with severe IBS-D.

Dosage: 0.5-1mg tablet.

Special considerations or risks: Serious and sometimes fatal gastrointestinal adverse events including ischemic colitis, and serious complications of constipation, have been reported. Alosetron should not be used among individuals with a history of constipation, adhesions, intestinal obstruction or stricture, impaired intestinal circulation, inflammatory bowel disease, diverticulitis, or a hypercoagulable state. Discontinue use immediately in patients who develop symptoms of constipation or ischemic colitis.

Most common side effects: Constipation, ischemic colitis.

Recommendation: ACG recommends alosetron for overall symptom improvement in women with severe IBS-D.