Severe diarrhea

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: Small	Size of stool: Medium	Size of stool: Large
1 to 4	Mild diarrhea	Mild diarrhea	Moderate diarrhea
5 to 8	Mild diarrhea	Moderate diarrhea	Moderate diarrhea
9 to 12	Moderate diarrhea	Moderate diarrhea	Severe diarrhea
12 to 16	Moderate diarrhea	Severe diarrhea	Severe diarrhea
16 or more	Severe diarrhea	Severe diarrhea	Severe 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.