Alosetron for irritable bowel syndrome


Generic Name Brand Name
alosetron hydrochloride Lotronex

How It Works

Alosetron slows the movement of stools through the bowels.

Why It Is Used

Alosetron is used to treat severe irritable bowel syndrome (IBS) in some women who have failed to respond to other treatments for severe diarrhea.

IBS is a disorder of the intestines that causes abdominal pain or discomfort with constipation or diarrhea (and sometimes alternating episodes of both). Other common symptoms include bloating and passing mucus in the stools. The condition is more common in women than in men.

How Well It Works

Studies have shown that alosetron improves abdominal discomfort and reduces diarrhea and urgency of bowel movements.1

Side Effects

The main side effect of alosetron is constipation, which occurred in 25% to 30% of people.2 Other side effects include nausea and abdominal discomfort and pain.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

After alosetron was first approved by the U.S. Food and Drug Administration (FDA) for treatment of IBS, some people taking the medication suffered from serious side effects, including severe constipation or reduced blood flow to the large intestine (ischemic colitis). Side effects led to surgery to correct the problem and, in a few cases, death. The medication was removed from the market.

However, in June 2002, the FDA approved alosetron for reintroduction with very specific guidelines:

  • Alosetron is for use only in women who suffer from severe IBS whose main symptom is diarrhea and who failed to respond to previous treatment.
  • You must sign a patient-physician consent form before taking alosetron.
  • Only those physicians who are enrolled in the Prescribing Program for Lotronex can prescribe alosetron.

If you are taking alosetron and you experience constipation, abdominal pain, rectal bleeding, or bloody diarrhea, stop taking the medication and contact your health professional.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.



  1. Tack J (2006). Irritable bowel syndrome. In MM Wolfe et al., eds., Therapy of Digestive Disorders, 2nd ed., pp. 701–710. Philadelphia: Saunders Elsevier.
  2. Mertz HR (2003). Irritable bowel syndrome. New England Journal of Medicine, 349(22): 2136–2146.

Last Updated: May 23, 2008

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