Medicine for Diarrhea Predominant IBS

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Diarrhea predominant irritable bowel syndrome (IBS-D) and its symptoms of severe abdominal pain and cramping, and frequent, urgent bouts of loose, watery diarrhea, is a disruptive health problem. Although limited, there are some medications that might be prescribed in an attempt to relieve symptoms. Some of these medications are designed specifically for IBS-D, while others are used to address certain symptoms, and others are used in an off-label manner. Here you will find an overview of the primary medications that your doctor might choose for you.

Over-the-Counter Medication

For many people who have IBS-D, Imodium, an over-the-counter antidiarrheal medication is something that is typically kept close at hand. Imodium is taken orally and is usually well-tolerated. It works on diarrhea by decreasing the speed of intestinal contractions and the amount of fluid in the large intestine. This results in less urgency and a firmer stool. Unfortunately, imodium does not seem to have much of an effect in terms of reducing abdominal pain.

Prescription Medications

The following medications have received FDA approval for the treatment of IBS-D:

Xifaxan: Xifaxan (rifaximin) is an antibiotic that works differently than the antibiotics that you might be familiar with. Xifaxan is not absorbed in the stomach and therefore its actions are thought to occur locally in the small intestine. The use of Xifaxan as a treatment for IBS-D arose from research that suggests that small intestinal bacterial overgrowth (SIBO) might be a contributing factor to the symptoms of IBS-D. Because the medication works locally, it is typically well-tolerated and does not have the impact on bacteria within the large intestine that other antibiotics have. In research studies, Xifaxan has demostrated efficacy in reducing abdominal pain, diarrhea episodes and bloating.

Viberzi, Truberzi (Europe): Viberzi (eluxadoline) works on opioid receptors within your digestive system. These receptors regulate the speed of intestinal contractions, fluid secretion and pain sensations. Viberzi works locally and therefore side effects are usually minimal. Viberzi is labelled a "controlled substance" because there is a risk that it could become habit-forming. In research studies, Viberzi has been shown to reduce diarrhea episodes and abdominal pain.


Antispasmodic (anticholinergic) medications are frequently prescribed for the relief of abdominal pain and cramping in people who have IBS-D. These medications target and reduce the neurotransmitter acetylcholine in the nervous system. The benefit of these medications for IBS=D comes from the reduction in the secretion of mucus and a reduction in intestinal spasms. There is some moderate research support for the pain-relieving properties of antispasmodics for IBS. Antispasmodics prescribed for IBS include:

  • Bentyl (Dicyclomine)
  • Anaspaz, Cystospaz, Levbid, Levsin (Hyoscyamine, hyoscamine)
  • Buscopan (Hyoscine butylbromide)


Although commonly prescribed for the treatment of depression and anxiety, antidepressants are sometimes prescribed due to their beneficial effects on IBS symptoms. It is not yet known precisely why this positive effect occurs. It may be due to the medication having an effect on neurotransmitters found in both the brain and the gut, it may have something to do with an effect on the communication between the gut and brain in terms of the stress response, or it may have to do with the effect of these medications on the parts of the brain that are involved in stress and/or pain response. In any case, antidepressants can serve to relieve pain and slow down bowel movements, particularly when a tricylic antidepressant is chosen. Prescribing an antidepressant for IBS is considered "off-label," but is recommended by the American College of Gastroenterology.

Bile Acid Binders

Emerging​ research has indicated that approximately one-third of all cases of IBS-D might actually be attributable to a condition known as bile acid diarrhea (BAD). A sign of this might be that diarrhea episodes occur immediately after eating. This condition may benefit from an off-label use of medications known as bile acid binders. These medications include:

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