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Watery Stool – Causes of Liquid, Fluid Bowel Movement, Feces

Feces should be firm, soft, and elongated like a sausage. This type of “normal” stool is defined in the Bristol Stool Chart as type 3 or type 4 stool. Refer to different types of feces for a graphical representation of the various forms according to the Bristol Stool Chart.

Watery stool (type 7) or mushy stool (type 6) is an indication that the water content in the stool is higher than normal. On average, water should account for approximately 70% of the stool weight, With more fluid stool, the water content to solid matter content is significantly higher than normal.

Watery stool is not diarrhea unless it meets with the following criteria :

  • more than 3 bowel movements in a day
  • total volume exceeding 200 grams or 200 milliliters per day

In most cases, watery stool occurs as a case of diarrhea. Read more on Diarrhea and Normal Bowel Movement.

Causes of Watery Stool

  • Infections account for most cases of acute watery stool (watery diarrhea). The microorganisms responsible for infectious gastroenteritis are a major cause. Chronic cases of infectious diarrhea may be seen in immunocompromised patients (as seen in HIV diarrhea) or associated with a Clostridium difficile infection (as seen in antibiotic-associated diarrhea).
  • Malabsorption syndromes are another common cause of watery stool or watery diarrhea. In these cases, there is failure of the small intestine to absorb nutrients, which is further compounded by decreased water absorption in the large intestine. The most prominent sign, apart from the watery diarrhea, is fat in the stool (steatorrhea) which gives the stool a greasy appearance and tendency to float (‘floaters’).
  • Chronic intestinal conditions like inflammatory bowel disease (Crohn’s disease, ulcerative colitis) frequently result in watery stool, either as episodes of diarrhea or changes in stool consistency without frequent or large volume evacuations.
  • Food intolerance and allergies where the intestines are unable to process certain foods thereby eliciting symptoms similar to a malabsorption syndrome, the most notable of which is watery diarrhea. This often follows the consumption of the problem foods like dairy in lactose intolerance, gluten in celiac disease or fruits in fructose malabsorption.
  • Poor dietary habits where the diet is full of processed foods, caffeinated drinks, saturated fats and spicy or pungent foods (chilli, hot peppers). This is dependent on individual tolerance and the amount of trigger foods consumed in one sitting. Overeating and dieting or fasting may also trigger watery stool.
  • Medication and toxins either as a result of pharmaceutical drug use, narcotics or poisons which may be intentionally or accidentally consumed.
  • Psychological factors like stress, anxiety and depression may affect normal bowel movement and result in watery stool or watery diarrhea.
  • Diarrhea due to other disorders may be seen in a number of diseases where the organ, even if not part of the gastrointestinal tract, play crucial roles in bowel functions – digestion and absorption. For example, pancreatitis, gallstones and liver disease. Watery stool may also occur in conditions not linked directly to digestion and absorption of foods as is the case with hyperthyroidism.