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Mild, Moderate, or Severe Diarrhea

Topic Overview

Diarrhea is described as an increase in the frequency of bowel movements or a decrease in the consistency of stools that causes the discharge of watery, loose stools. The severity of diarrhea is determined by the size and number of stools passed within a period of time.

The following table will help you decide whether you have mild, moderate, or severe diarrhea.

Mild, moderate, or severe diarrhea
Number of stools within the past 24 hours Size of stool: SmallSize of stool: MediumSize of stool: Large
1 to 4Mild diarrheaMild diarrheaModerate diarrhea
5 to 8Mild diarrheaModerate diarrheaModerate diarrhea
9 to 12Moderate diarrheaModerate diarrheaSevere diarrhea
12 to 16Moderate diarrheaSevere diarrheaSevere diarrhea
16 or moreSevere diarrheaSevere diarrheaSevere diarrhea

Severe diarrhea has many causes. Stomach flu (gastroenteritis) or food poisoning may cause severe diarrhea. Drinking untreated water that contains the Giardia lamblia parasite can cause diarrhea that develops 1 to 4 weeks later.

Severe diarrhea increases your risk for dehydration by causing your body to lose large amounts of fluid quickly. It is important to increase your intake of fluids, such as water or a rehydration drink, and to watch for symptoms of dehydration.

Persistent diarrhea can have many causes, including dietary changes, stress, irritable bowel syndrome, and certain medicines. Occasionally, persistent diarrhea can be a symptom of a more serious condition, such as a chronic infection, inflammatory bowel disease, a malabsorption syndrome, or colorectal cancer.

Related Information


ByHealthwise Staff
Primary Medical ReviewerWilliam H. Blahd, Jr., MD, FACEP - Emergency Medicine
Specialist Medical ReviewerH. Michael O'Connor, MD - Emergency Medicine
Last RevisedApril 26, 2010

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