Lotronex (alosetron HCl)

Reviewed by: HU Medical Review Board | Last reviewed: March 2023

Lotronex (alosetron HCl) is a prescription medicine for women with severe chronic irritable bowel syndrome with diarrhea (IBS-D). Lotronex may help women who have severe diarrhea from IBS, who have been experiencing IBS-D for six months or longer, and who have not gotten relief from any other medicines they have tried.1

Lotronex is a serotonin 5-HT3 receptor antagonist. Serotonin is a chemical in the body that is involved in the messages of pain perception, the sleep-wake cycle, and mood. Ninety-five percent of all the serotonin in the human body is found in the gut. As an antagonist, Lotronex blocks the receptor sites where serotonin usually binds.1

It is believed that too much serotonin in the gut may cause bowel movements to occur too quickly, leading to bowel urgency and diarrhea, as well as more sensitivity to pain and discomfort in the abdomen. Blocking the serotonin from binding to the receptors may help reduce some of the symptoms of severe IBS with diarrhea.1

Taking Lotronex

Lotronex works by reducing the effects of having too much serotonin in the intestines. It is recommended that people who are prescribed Lotronex take it every day – not just when symptoms flare.1

Who should not take Lotronex

There has not been enough data to support if Lotronex is safe and effective for men or for children under the age of 18. In addition, Lotronex should not be used by people with IBS with constipation (IBS-C) or by people who are currently experiencing constipation. People who have experienced bowel blockages, blood clots, Crohn’s disease, ulcerative colitis, diverticulitis, severe liver disease, ischemic colitis or who are taking a drug called Luvox® (fluvoxamine) should not take Lotronex.1

There are no studies that demonstrate Lotronex is safe during pregnancy or for women who are breastfeeding, as it may cause harm to the child. Women who are pregnant or breastfeeding should discuss treatment options with their doctor.1

Possible side effects when taking Lotronex

The most common side effects experienced by people taking Lotronex are constipation, stomach pain, and nausea. If a person experiences constipation while taking Lotronex, they should immediately stop taking it and call their doctor.

Lotronex has a boxed warning, the strictest warning from the US Food and Drug Administration (FDA). It has this warning because severe complications have been experienced by people on Lotronex, including severe constipation and ischemic colitis. Ischemic colitis is a condition where blood flow to the intestines is reduced or blocked, which may cause pain and damage to the colon. These complications can lead to hospitalization, blood transfusions, surgery and even death.2,3

These are not all the possible side effects of Lotronex. Talk to your doctor about what to expect or if you experience any changes that concern you during treatment with Lotronex.

Additional treatment options for IBS

The imbalance of serotonin, which is believed to cause some IBS symptoms, also plays a role in mood and may be the reason why some antidepressants are effective for IBS people.4

The management of IBS symptoms is usually accomplished by a combination of approaches, and determining the best combination for a person may require some trial and error. There are several drugs that people can try, as well as other treatment strategies such as adding exercise, making dietary changes, adding fiber, or trying complementary or alternative medicine.

Before beginning treatment for IBS, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you take. This includes over-the-counter drugs.

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