Medications for Diarrhea-Predominant Irritable Bowel Syndrome (IBS-D)

Nurse giving pills to a patient

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You can usually relieve the symptoms of diarrhea-predominant irritable bowel syndrome (IBS-D) with over-the-counter (OTC) diarrhea medications like Pepto-Bismol and Imodium. However, these drugs are not meant to be used for more than a few days.

In some cases, prescription drugs may be needed to relieve frequent or urgent bouts of loose, watery diarrhea along with abdominal pain and cramping. These include medications like Lotronox (alosetron), Viberzi (eluxadoline), and Xifaxan (rifaximin) that have been specifically approved for the treatment of IBS-D by the U.S. Food and Drug Administration (FDA).

This article lists the OTC and prescription drugs commonly used for diarrhea-predominant IBS. These include some drugs that are frequently used off-label when other options fail to provide relief.

Over-the-Counter Medications for IBS-D

If you have IBS-D, OTC antidiarrheals may be effective in relieving your acute (sudden, severe) diarrhea. However, they can cause side effects if misused or overused. These drugs should only be used under the direction of a healthcare provider for a limited period.

Imodium (Loperamide)

Imodium (loperamide) is a popular medication taken orally (by mouth) to treat occasional diarrhea. It works by slowing intestinal contractions, thereby increasing the absorption of water from stool. This creates firmer stools and reduces the frequency of bowel movements.

Imodium should not be used for more than two days without your healthcare provider's OK. Doing so can lead to constipation and, on rare occasions, a potentially life-threatening complication called toxic megacolon in which the dilation (widening) of the large intestine can cause bowel perforation, internal bleeding, and death.

Pepto-Bismol, Kaopectate (Bismuth Subsalicylate)

Medications containing bismuth subsalicylate—like Pepto-Bismol and Kaopectate—can also relieve diarrhea along with stomach upset and indigestion. They do so by increasing the absorption of sodium and chloride through the wall of the intestine, pulling water molecules along with them.

Taking bismuth subsalicylate for more than two days is not recommended because it can alter the balance of fluids and electrolytes in the body. This can lead to dizziness, muscle spasms, heart palpitations, and tinnitus (ringing in the ears).

Can Probiotics Help IBS-D Symptoms?

Probiotics will not stop an acute episode of IBS-associated diarrhea, and it is unclear how helpful they are in the long-term management of the disease. Some studies suggest that probiotic supplements may help ease IBS-D symptoms over time, while others found no such benefit.

Prescription Medications for IBS-D

There are a host of prescription drugs that can be used to relieve diarrhea in people with IBS. Some are specifically indicated for the treatment of IBS-D, while others are used off-label (meaning for purposes other than what they are licensed for).

Xifaxan (rifaximin)

Xifaxan (rifaximin) is an antibiotic approved by the FDA for the treatment of IBS-D. Like all antibiotics, Xiafaxin works by neutralizing bacteria—in this case, those living in the gut.

Research suggests that IBS-D may be caused in part by the overgrowth of bacteria. Bringing down the bacterial population may help ease diarrhea and other gastrointestinal symptoms.

Xifaxan is used for IBS-D because, unlike other antibiotics, the drug is poorly absorbed by the gut and remains largely in the intestine. Its limited action may help ease acute IBS-D episodes and prevent recurrence.

Xifaxan is taken by mouth for no longer than two weeks. Side effects include dizziness, lower back pain, frequent urge to urinate, jitteriness, and trouble sleeping.

Viberzi (Eluxadoline)

Viberzi (eluxadoline) is FDA-approved to treat diarrhea and stomach pain in people with IBS-D. It blocks signals from the brain to the intestines that regulate peristalsis (intestinal contractions). By doing so, it allows more water to be absorbed from stool.

Viberzi is taken twice daily with food but only for as long as your healthcare provider thinks you need it. It is listed as a controlled substance due to a risk of drug dependence (addiction).

Side effects include nausea, constipation, bloating, vomiting, runny or stuffy nose, and upper respiratory infection.

Lotronox (Alosetron)

Lotronox (alosetron) is FDA-approved for females with IBS-D who have not improved with conventional therapy. It works by blocking the action of a neurotransmitter called serotonin that helps trigger peristalsis.

Lotronox is only used when severe IBS-associated diarrhea persists for six months. The drug is used with such caution because it can lead to a potentially severe complication called ischemic colitis in which reduced blood flow to the colon can lead to tissue death, bowel perforation, or bowel obstruction.

Lotronox is not used in males because the concentration of the drug in the blood is typically lower than in females, Because of the reduced therapeutic effect, the benefits may not outweigh the risks.

Lotronox is taken once or twice daily by mouth. Common side effects include constipation, nausea, stomach pain, shakiness, heartburn, and headache.

Lomotil (Diphenoxylate/Atropine)

Lomotil (diphenoxylate/atropine) is a prescription drug used to treat diarrhea caused by many different conditions. It is used off-label for IBS-D, usually when severe diarrhea cannot be controlled with OTC antidiarrheals.

As with Imodium, Lomotil slows down intestinal contractions, relieving diarrhea and easing stomach pain. Lomotil can be taken by mouth up to four times daily, typically for no longer than 10 days for adults or two days for children.

Side effects of Lomotil include drowsiness, dizziness, itchy skin, nausea, dry skin, restlessness, and malaise (a general feeling of unwellness).

Antispasmodics

Antispasmodic medications are frequently prescribed for the relief of abdominal pain and cramping caused by many different conditions. The drugs block the action of acetylcholine, a neurotransmitter that triggers muscle contractions throughout the body, including the gut.

Antispasmodics prescribed off-label for IBS include:

Despite their frequent use, the American College of Gastroenterology (ACG) recently came out against the use of antispasmodics, citing the lack of evidence that the drugs help ease IBS symptoms.

Side effects include constipation, dry skin, dry mouth, dizziness, bloating, and decreased urination. Some antispasmodic are taken up to four times daily to treat acute IBS-D symptoms.

Antidepressants

Although commonly prescribed for the treatment of depression and anxiety, antidepressants may have beneficial effects for people with IBS-D.

Tricyclic antidepressants and selective serotonin reuptake inhibitors (SSRIs) both appear to reduce symptoms of IBS-D by altering the availability of neurotransmitters in the gut, including serotonin.

Antidepressants commonly used for IBS-D include:

Though the use of antidepressants to treat IBS-D is considered off-label, the drugs remain widely prescribed because they are often very effective and generally well tolerated. They can also ease anxiety and stress that can trigger IBS symptoms.

Side effects include nausea, drowsiness, dry mouth, insomnia, dizziness, and sexual problems like low sex drive and erectile dysfunction. Antidepressants are typically dosed on a once-daily schedule.

Bile Acid Sequestrants

Around 28% of people with IBS-D have a severe form of diarrhea called bile acid diarrhea (BAD). BAD occurs when an excessive amount of bile acids is produced by the liver, which starts to accumulate in the intestine. The increased acidity promotes fluid secretion in the lining of the gut, leading to diarrhea.

Drugs classified as bile acid sequestrants (a.k.a. bile acid binders or bile acid resins) are sometimes prescribed to people with IBS who have evidence of BAD. These drugs are not recommended for the general treatment of IBS-D.

Bile acid binders sometimes used to treat IBS-D include:

Side effects of bile acid sequestrants include constipation, stomach pain, bloating, vomiting, heartburn, loss of appetite, indigestion, and upset stomach. The drugs are typically taken once daily until symptoms ease.

Summary

Diarrhea-predominant irritable bowel syndrome (IBS-D) can be treated with over-the-counter (OTC) and prescription medications. OTC options include antidiarrheals like Imodium (loperamide) and bismuth subsalicylate found in Pepto-Bismol and Kaopectate.

Prescription drug options include those specifically approved by the FDA for the treatment of IBS-D, like Xifaxan (rifaximin), Viberzi (eluxadoline), and Lotronox (alosetron). Prescription drugs used off-label for IBS-D include Lomotil (diphenoxylate/atropine), antispasmodic, antidepressants, and bile acid sequestrants.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Barbara Bolen, PhD

By Barbara Bolen, PhD
Barbara Bolen, PhD, is a licensed clinical psychologist and health coach. She has written multiple books focused on living with irritable bowel syndrome.