Diarrhea Classification Guidelines

Classification by Duration

Diarrhea is classified primarily based on duration, with key categories being acute (lasting <14 days), prolonged (lasting 7-13 days), persistent (lasting 14-29 days), and chronic (lasting ≥30 days), as defined by the Infectious Diseases Society of America 1, 2
Acute diarrhea is defined as an episode lasting less than 14 days, according to the Infectious Diseases Society of America 3, 4
Prolonged diarrhea is defined as an episode lasting 7-13 days, as stated by the Infectious Diseases Society of America 1, 2, 5
Persistent diarrhea is defined as an episode lasting 14-29 days, as defined by the Infectious Diseases Society of America 1, 2
Chronic diarrhea is defined as an episode lasting 30 days or longer, according to the Infectious Diseases Society of America 1, 2

Acute watery diarrhea is characterized by loose or liquid stools without blood, including cholera, as defined by the Infectious Diseases Society of America 1, 2
Acute bloody diarrhea (dysentery) is characterized by frequent scant stools with blood and mucus, according to the Infectious Diseases Society of America 1, 2

Travelers' diarrhea can be classified as mild (tolerable, not distressing, and does not interfere with planned activities), moderate (distressing or interferes with planned activities), or severe (incapacitating or completely prevents planned activities), as defined by the International Society of Travel Medicine 6, 7, 8
Severe diarrhea is characterized by being incapacitating or completely preventing planned activities, and all dysentery (passage of grossly bloody stools) is considered severe, according to the International Society of Travel Medicine 6, 7, 8

The clinical approach to classification involves assessing stool characteristics (frequency, consistency, presence of blood), considering the definition of diarrhea, and evaluating the functional impact of diarrhea on daily activities, as recommended by the Infectious Diseases Society of America 3, 4 and the International Society of Travel Medicine 6, 7, 8
For epidemiological investigations, diarrhea is often defined as ≥3 loose or liquid stools per day, according to the Infectious Diseases Society of America 3, 4

The presence of blood in stool (dysentery) always indicates severe disease requiring prompt evaluation, as stated by the International Society of Travel Medicine 6, 7, 8
Infectious diarrhea may present with accompanying symptoms like nausea, vomiting, or abdominal cramps, according to the Infectious Diseases Society of America 3, 4