Causes of Chronic (Prolonged, Persistent, Constant) Diarrhea

Diarrhea is a common digestive symptom that affects every person at some point in life. It may occur several times in a year. Usually diarrhea is acute meaning that it lasts for a short period of time but tends to be severe. Acute diarrhea usually lasts for only a few days and often resolves on its own. However, there are instances where diarrhea persists and this may be referred to as chronic diarrhea.

Definition of Chronic Diarrhea

Diarrhea (loose bowel movements) is considered as chronic when it lasts for more than 2 weeks (1). It is important to understand what the term diarrhea means, whether it is acute or chronic. Diarrhea is defined as having more than three bowel movements in a 24 hour period where the stool is of a liquid or watery consistency. Another definition is the passing of more than 200g (grams) or 200mL (milliliters) within a 24 hour period.

Therefore chronic diarrhea is the passage of watery stools in more than three bowel movements within 24 hours that extends for more than two weeks. Depending on the underlying cause, chronic diarrhea can lead to dehydration, malnutrition or nutritional deficiencies and failure to thrive (FTT) in young children. In severe cases it can even lead to death, mainly as a consequence of dehydration.

While acute diarrhea may resolve on its own within a few days to a week, chronic diarrhea often requires medical intervention. It is therefore important to consult with a medical professional about the underlying cause of persistent diarrhea. The prescribed treatment is relevant to the underlying cause of the chronic diarrhea and may not always be directed at the abnormal bowel movements, as is the case when using antidiarrheal drugs such as loperamide.

Why does diarrhea occur?

Diarrhea is a consequence of several disturbances in the gut.

  • Faster than normal movement through the bowels (bowel motility) may push the intestinal contents rapidly through the bowel before water can be reabsorbed in the colon. This gives rise to liquid stools.
  • Damage to the bowel wall and disruption of the water-electrolyte balance can cause water to remain in the bowels or even draw out water from the body thereby leading to liquid stools.

Sometimes bowel movement may be more frequent than is considered normal. It may even surpass three bowel movements in a day but the stool is of a normal consistency. Despite the frequency, there appears to be no underlying abnormality in the bowel wall or in the composition of stool. This may be referred to as functional diarrhea which infers an abnormality in bowel physiology without there being any underlying disease.

Read more on frequent bowel movements.

Common Causes of Chronic Diarrhea

Most of the time acute diarrhea is due to infections like viral gastroenteritis and food poisoning. It is often accompanied by other symptoms like nausea and vomiting, abdominal pain, bloating and excessive flatulence. Unlike sudden (acute) diarrhea, chronic diarrhea is mostly of non-infectious origin and there may be no other symptoms beyond the frequent and watery stools that are characteristic of diarrhea.

  • Irritable bowel syndrome (IBS) appears with alternating diarrhea and constipation, abdominal pains, triggered by stress or certain foods and relieved by bowel movement. Diagnosis is made after exclusion of other bowel disorders.
  • In lactose intolerance, diarrhea and bloating appear within hours after ingesting dairy or other products containing lactose.Diagnosis is made by a breath test with lactose
  • In food allergies, tingling lips, itchy throat or skin or diarrhea may appear within few minutes or, in delayed response, within several hours after ingestion of allergenic food. Antihistamine pill usually bring relief in few hours
  • In fructose malabsorption, diarrhea and abdominal bloating appear within 48 hours after a meal rich in fructose or sorbitol. Diagnosis is made by a breath test with fructose. Toddler’s diarrhea may appear in small children fed with large amounts of fruit juices.
  • Intestinal parasites , including intestinal worms, mostly cause mild diarrhea with waxing and waning course, abdominal bloating, mucus, blood or parts of intestinal worms in the stool. Weight loss is common. Giardia may cause sulphur smelling gas.
  • Inflammatory bowel disease (IBD): Crohn’s disease and ulcerative colitis may appear with low grade fever, fatigue, nausea, lower left or lower righ abdominal pain, skin rash, diarrhea. Diagnosis is made by colonoscopy.
  • In celiac disease, diarrhea appear within hours after ingesting gluten-containing foods (wheat, rye or barley). Diagnosis can be made if symptoms cease after gluten-free diet and is confirmed by investigation of a sample of duodenal mucosa.
  • Liver disease, like cirrhosis or chronic hepatitis, may appear withupper right abdominal pain, jaundice, swollen abdomen, fatigue and diarrhea.
  • Gallbladder disease typically presents with cramping pain below the right ribs, appearing within an hour after the meal. White diarrhea appears if bile ducts are blocked.
  • Acute or chronic pancreatitis and pancreatic cancer appear withupper middle (or upper left or right) abdominal pain. White bowel movements/diarrhea appears in developed disease.
  • Diverticulitis appears withpain in lower left abdomen, bloating, fever and diarrhea.
  • Small intestinal bacterial overgrowth (SIBO) may be due reduced small intestinal motility in diabetes or partial bowel obstruction or may appear together with fructose malabsorption or lactose intolerance. Abdominal bloating, early satiety, excessive burping and gas (sometimes with sulphur smell) and, sometimes, diarrhea are main symptoms. Diagnosis is with breath test with lactulose.
  • In alcoholism, diarrhea is usually caused by liver or pancreatic disease and malnutrition. Weight loss is typical.
  • Malnutrition results from insufficient nutrient or calorie intake in starvation or intestinal malabsorption. It is common in children in poor areas and in alcoholics. Obvious underweight, fatigue, diarrhea and pale skin due to anemia are typical symptoms.
  • Medications, like antibiotics, laxatives (if abused), anti-acid drugs with magnesium, some drugs for treating  high-pressure and other drugs or remedies (read leaflets!) may cause chronic diarrhea.

Rare Causes of Chronic Diarrhea

Rare causes of chronic diarrhea include diabetes, chronic infections and poisoning, ischemic colitis, systemic sclerosis, hormonal disorders, cancer, kidney failure, short bowel syndrome, inborn diseases, and paradoxical diarrhea in constipated children.

Related Articles:


  1. Definition of chronic diarrhea
About Jan Modric (209 Articles)
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