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Medications can help improve diarrhea and constipation or assist in the development of a more predictable bowel pattern. Examples include antidiarrheal medications, laxatives, fiber supplements, and stool softeners.


Antidiarrheal agents such as loperamide and diphenoxylate can be effective in decreasing bowel movement frequency, improving stool form by enhancing intestinal water and ion absorption, and increasing anal sphincter tone at rest. These physiologic actions seem to explain the improvement in diarrhea, urgency, and fecal soiling observed in patients who use these products. These medications do not typically relieve abdominal pain and may cause constipation.


A laxative is a medication that increases bowel function. There are four main classes of laxatives: fiber, osmotic laxatives, stimulant laxatives, and emollients.

Fiber is discussed below. Osmotic laxatives are poorly absorbed compounds that cause an influx of water into the small intestine and colon, thereby increasing stool bulk. Stimulant laxatives have a direct stimulating effect on the network of nerves in the large intestine and reduce absorption of water and electrolytes from gastrointestinal contents. Stimulant laxatives take effect within hours of ingestion. Emollients act as stool softeners.

Fiber supplements

The type of fiber – either soluble (in water) or insoluble – can make a difference. Soluble fiber dissolves in water and forms a gel when water is added to it. Insoluble fiber absorbs liquid and adds bulk to stool.

If you find that fiber is gas producing or seems to be a problem that causes you to feel bloating or pain, it is usually insoluble fiber (mainly found in cereals or whole grains) that is the problem. Soluble fiber, mainly found in vegetables and fruits, is less likely to be a problem.

When adding fiber to the diet, it is best to do so slowly over a period of weeks. If gas or distention occur, try reducing the dose of fiber and reducing consumption of gas-producing foods, such as beans, cabbage, legumes (e.g., peas, peanuts, soybeans), apples, grapes, and raisins.

Learn more about dietary fiber

Stool softeners

Stool softeners provide moisture to the stool and prevent dehydration. These laxatives are often recommended after childbirth or surgery. (e.g., Colace and Surfak.)

Learn more about dietary tips 

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