Chronic diarrhea has many causes. Some are caused by disease. This article focuses mostly upon those causes where you can make changes that may result in a rapid improvement.

This type of diarrhea is usually painless and persistent, and there are no signs of disease such as bleeding, anemia, weight loss, or fatigue. Frequent loose stools are a daily occurrence. There may be occasional normal stools. Despite the need to stay within reach of a toilet, the person is otherwise well.

Very frequently, the diarrhea is due to something in the diet that is taken in excess. Usually this is an excess of a sugar or chemical substance. Common examples are alcohol and caffeine. An excess of alcohol, especially beer and wine, may cause loose stools the next day. The best test is to stop alcohol completely and see if the diarrhea stops. If it does, drinking may be cautiously resumed at a more modest level.

Caffeine-containing drinks

Caffeine- containing drinks have a laxative potential. More than two or three cups of coffee or tea daily can often cause diarrhea. Withdraw gradually over the course of a few days to avoid headache and try going without for awhile. Decaffeinated drinks may still contain chemicals that can loosen the stools. Most people can tolerate smaller amounts well.

Some sugars can cause diarrhea. For example, the artificial sugar sorbitol is used as a sweetener. It is often used in diet gums and candies or as a sugar substitute in coffee or tea. It has no calories, but is a known laxative if taken in sufficient amount. Mannitol is another sweet substance frequently found with sorbitol.


Fructose is a natural calorie-containing sugar found in fruit. It is one reason why large amounts of fruit can cause diarrhea. It may also be found in candies, soft drinks, honey, and preservatives and, in sufficient amounts, can cause diarrhea. Many people notice that their bowel movements are looser and more frequent in the summer when fresh fruits and vegetables are freely available. Moderating intake should help.

Lactose intolerance

Lactose intolerance is the cause of chronic diarrhea in some people. Lactose is a sugar that is contained in cow’s milk. Its proper digestion requires the adequate presence of an enzyme (lactase) in the wall of the small intestine. Treatment of lactose intolerance initially involves the elimination of all lactose-containing products from the diet. Moderate amounts of dairy or modified dairy products may be gradually reintroduced into the diet as tolerated.


Laxatives are frequently present in herbal medicines. Senna tea is an obvious example. But herbs with a laxative effect like senna can be found in many other popular remedies. The contents of an herbal remedy may not all appear on the package. Only by stopping the medicine for a trial period can one be confident that it is not the cause of diarrhea.

Other Possible Causes of Chronic Diarrhea


Many regular medicines can have diarrhea as an unwanted side effect.

A list of suspects includes:

  • misoprostol
  • antacids containing magnesium hydroxide
  • laxatives
  • stool softeners
  • drugs for “regularity”
  • alcohol
  • caffeine

It pays to be cautious of any regularly consumed drug or “natural” remedy.


True food allergies are rare as a cause of chronic diarrhea. If an elimination diet is embarked upon (they are very difficult), one must take care not to end up with a nutritionally deficient diet. Supervision by your doctor is important here.


Occasionally, chronic unexplained diarrhea may be due to an infection with an intestinal parasite. These are more common is some parts of the world. This may be detected in some cases by stool tests, or more accurately by a biopsy of the upper small intestine.


If one is suffering from chronic diarrhea, it is important to note if there have been previous intestinal operations. Diarrhea can sometimes be a complication. Inform your doctor of the precise nature of any previous abdominal surgery, since this type of diarrhea is often treatable.


If you have chronic diarrhea you should carefully review with your doctor all that you eat and drink, and your past surgical, drug, and travel history. This may disclose a cause that can be remedied.

Careful consideration of these everyday items may avoid extensive and costly tests and lead to earlier relief.

Suffering from more than just chronic diarrhea?  Visit to learn more

Learn more about chronic and functional diarrhea 

Watch this 2021 NES presentation by Dr. Brooks Cash, Chief of the Division of Gastroenterology, Hepatology, and Nutrition at the University of Texas Health Science Center at Houston.

Adapted from IFFGD publication #150 by W. Grant Thompson, MD, FRCPC, Emeritus Professor of Medicine, University of Ottawa, Ontario, Canada

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