Rare Causes of Chronic Diarrhea in Adults and Children

Rare causes of chronic diarrhea (lasting over 3 weeks) are listed below; symptoms are added to help to recognize a cause.

Read about common causes of chronic diarrhea and causes of acute (sudden) diarrhea.

Causes of Chronic Diarrhea in Adults

1. Diabetes

Old patients with long lasting, poorly controlled diabetes may have:

2. Thyroid Disease

In hyperthyroidism, excessive thyroxine stimulates bowel muscles thus shortening intestinal transit time resulting in diarrhea. Other symptoms include bumps on the front side of the neck, bulging eyes, sweating and irritability.

3. Adrenal Gland Disorders

In Addison’s disease, production of hormones aldosterone and cortisol is reduced. Resulting low blood pressure and poor blood perfusion of the small intestine affect absorption of nutrients thus causing diarrhea. Other symptoms include skin darkening, salt craving, weakness and lightheadedness.

4. Kidney Disorders

Renal (kidney) failure (uremia)  is an inability of kidney to filter urea (breakdown product of proteins) from the blood into urine. Symptoms may include left or right back side pain, nausea, fatigue, headache, itchy skin and diarrhea.

5. Bowel Infections

Chronic bowel infections like tuberculosis, shigellosis, amebiasis or infections appearing in AIDS  may cause low-grade fever, blood in the stool, urgency to have bowel movement and diarrhea. Drugs for treating AIDS may also cause diarrhea.

6. Heavy Metals

Chronic poisoning with heavy metals, such as lead, mercury, arsenic and cadmium may cause chronic diarrhea. Metals may be ingested with water (lead pipes), inhaled (mercury vapor) or they may come through the skin. Symptoms include tingling face or limbs, abdominal cramps, diarrhea, deposits of metals in the gums and so on.

7. Lymphocytic Colitis

Lymphocytic (collagenous) colitis usually affecting people after age of 60 may cause diarrhea, left lower abdominal pain and blood in the stool.

8. Systemic Sclerosis

Insystemic sclerosis, overgrowth of connective tissue in the gut may hamper intestinal absorption or cause bacterial overgrowth, which both may cause diarrhea; on the other hand lowered intestinal motility may lead to constipation. Skin symptoms include thickening of the trunk skin, difficulty swallowing, color changes in fingers and toes on cold exposure – Raynaud’s phenomenon.

9. Abdominal Cancer

Cancer of the stomach, small intestine (rarely), colon, liver or pancreas may cause poor appetite, weight loss, malaise, nausea, tiredness, abdominal pain and blood in the stool.

Carcinoid tumor, usually affecting people after age of 60, may cause facial flushing, lightheadedness, itchy skin, diarrhea and other symptoms.

10. Peptic Ulcer

Peptic ulcer causes diarrhea only if it is connected with bacterial overgrowth or gastric hyper-acidity.

11. Other Causes

Other rare causes of chronic diarrhea include:

  • Endocrine tumors (gastrinoma, VIPoma)
  • Amyloidosis
  • Abetalipoproteinemia
  • Lymphangiectasia, etc.

12. Brainerd Diarrhea

In Brainerd, Minnesota (USA) in 1983, there was an outbreak of diarrhea where patients experienced explosive, watery, non-bloody diarrhea, (with urgency or stool incontinence), occurring 10-20 times a day. Almost all of the outbreaks occurred in the United States so far. The cause was not identified, but diarrhea was often connected with drinking unpasteurized milk or contaminated water. Brainerd diarrhea lasts from 4 weeks to 3 years and has a typical come-and-go course. There are no known complications and diarrhea is not contagious. There are no specific diagnostic signs and no specific treatment is available. Loperamide was reported to be helpful in about 50% of cases.

Rare Causes of Chronic Diarrhea in Children

Some inborn bowel disorders may cause diarrhea in infants.

Short bowel syndrome (SBS) appears as diarrhea after surgery (removing of large part of the small intestine), especially in small children.

Encopresis refers to stool soiling in chronically constipated children over 4 years of age without any organic bowel disease. Diarrhea occurs when a fresh soft stool passes the impacted stool. This is also called paradoxical diarrhea.


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