There are many possible causes of chronic diarrhea, which is defined as having watery, liquid or semisolid bowel movements for more than 4 weeks. Losing weight at the same time can mean that food is moving too quickly through your digestive system without proper digestion or absorption. Specific causes of chronic diarrhea and weight loss include infection, inflammatory disease, medication side-effects and sensitivity to certain nutrients such as gluten. Consult your doctor to determine the cause of the problem and the appropriate treatment.
Just Stress or Inflammatory Bowel Disease
High levels of stress can lead to chronic diarrhea and weight loss in some people. Being too quick to blame stress, however, can cause you to overlook a variety of conditions that interfere with normal digestion and absorption. Inflammatory bowel disease -- Crohn's and ulcerative colitis -- is one possible cause of diarrhea and weight loss. Crohn's disease, characterized by abscesses and ulcers in the small intestine, may produce abdominal pain, bloody diarrhea, fever, loss of appetite and weight loss. Ulcerative colitis usually starts in the rectum, causing an urge to defecate, blood or mucus in bowel movements and abdominal discomfort. It can also produce severe pain, watery or bloody diarrhea, fever, fatigue and weight loss.
Malabsorption or Maldigestion
Sometimes diarrhea and weight loss result from a specific problem with digesting or absorbing foods. If your pancreas does not produce enough digestive enzymes, fats pass through the intestines, causing watery or fatty-looking bowel movements, weight loss, malnutrition, smelly intestinal gas and abdominal distention. Malabsorption can also lead to chronic diarrhea and weight loss. Sometimes malabsorption is due to damage to the absorptive surface lining of the small intestine, such as in celiac disease. Weight-loss surgery and certain infections can also cause malabsorption. Some people with malabsorption may feel tired and have anemia, too.
Issues With Medications or Foods
Certain foods and medications can cause diarrhea and weight loss. Taking too many laxatives for constipation or weight loss, for example, can cause diarrhea. Other medications that list diarrhea as side effects include those taken for high blood pressure, heartburn, gout, indigestion, irregular heartbeats or pain, including nonsteroidal antiinflammatory drugs, or NSAIDS.
Antibiotics may destroy the friendly bacteria in your bowels, allowing undesirable bacteria such as Clostridium difficile to take over, a condition that causes serious diarrhea and weight loss. Intolerance to specific food items, such as lactose or gluten, can cause diarrhea and, in severe cases, weight loss.
Giardiasis, an infection caused by a protozoa, usually begins as a sudden bout of watery diarrhea within 2 weeks of eating contaminated food or drinking contaminated water. Some people develop a chronic form of giardiasis that causes foul-smelling stools, weight loss and bloating. Other possible causes of chronic diarrhea and weight loss include surgery that bypasses part of the intestine, microscopic colitis, parasites, thyroid disease and human immunodeficiency virus.
If you have chronic diarrhea and weight loss, you need to see your doctor. Contact your doctor right away if you have a fever of 101 degrees Fahrenheit or higher, small amounts of blood or pus in your bowel movements or symptoms of dehydration, such as thirst, fatigue, dizziness and scanty urination. Go to the emergency room if you have a fever of 103 degrees F or higher, moderate to large amounts of blood in your bowel movements or pain in your abdomen.