What medications help treat chronic diarrhea or irritable bowel syndrome?

Lawrence S. Friedman, MD
Antidiarrheals like loperamide (Imodium) and diphenoxylate with atropine (Lomotil) are generally recommended for patients whose main complaint is diarrhea. Loperamide, available over the counter, reduces the secretion of fluid by the intestine. Diphenoxylate, which is related to codeine and available by prescription only, helps to slow down intestinal contractions. It is combined with atropine in the prescription formulation.
William B. Salt II., MD
There are two main functional gastrointestinal disorders where diarrhea is a prominent symptom: (1) chronic functional diarrhea (at least 12 weeks, which need not be consecutive, in the preceding 12 months of loose (mushy) or watery stools that are present over 3/4 of the time without abdominal pain) and (2) the more common diarrhea-predominant irritable bowel syndrome , or D-IBS (more than three bowel movements per day, loose or watery stools and an urgency to have a bowel movement).

Treatment choices include the opioid agonists loperamide (a brand name Imodium; generic available) and diphenoxylate (a brand name Lomotil; generic available). Diphenoxylate also contains atropine, which is an antispasmodic.

Two drugs that are used to lower blood cholesterol can be helpful for some patients with chronic diarrhea, especially if the problem tends to occur in the morning, is triggered by meals or develops after surgical removal of the gallbladder. These drugs are cholestyramine (brand name Questran; generic available) and colestipol (brand name Colestid; generic available).

Narcotic drugs, such as codeine, are opioid agonists and have constipation as a potential side effect, so they may relieve diarrhea. However, because they cross into the brain, they can have unwanted side effects of sedation and drowsiness, and they can lead to physical dependency and addiction.

Unless a dietary factor can be identified as a trigger or cause of chronic diarrhea, opioid agonists are usually recommended first. Studies show that loperamide reduces the urgency and frequency of bowel movements in patients with diarrhea-predominant irritable bowel syndrome (IBS). Furthermore, loperamide can increase stool consistency and strengthen anal sphincter tone, which can be helpful if fecal incontinence is a problem. Loperamide does not get into the brain through the blood-brain barrier and is usually preferred over other opioids, such as codeine or diphenoxylate. However, none of these agents have been shown to relieve the pain associated with IBS. The drugs can either be taken regularly or on a prophylactic basis. If a "morning rush" occurs (diarrhea and/or stool urgency in the morning), then the drug could be taken at bedtime.

A study has shown that tricyclic antidepressant drugs (TCAs) may relieve diarrhea and associated pain in some patients with IBS, in part by their anticholinergic effects.
Irritable Bowel Syndrome & the MindBodySpirit Connection: 7 Steps for Living a Healthy Life with a Functional Bowel Disorder, Crohn's Disease, or Colitis (Mind-Body-Spirit Connection Series.)

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Irritable Bowel Syndrome & the MindBodySpirit Connection: 7 Steps for Living a Healthy Life with a Functional Bowel Disorder, Crohn's Disease, or Colitis (Mind-Body-Spirit Connection Series.)

Fast Facts on IBS: One in five people suffers from the frustrating symptoms of Irritable Bowel Syndrome (IBS). There is no simple answer--no pill, potion, or quick fix--that will cure IBS. But help...

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.