What are the most common causes of diarrhea?

From the Guidelines

Diarrhea is most commonly caused by norovirus and Salmonella enterica subspecies, which are the leading pathogens among the 24 gastroenteritis pathogens transmissible by food in the United States, as reported by the Foodborne Diseases Active Surveillance Network (FoodNet) national surveillance system maintained by Centers for Disease Control and Prevention (CDC) 1.

Common Causes of Diarrhea

The most common causes of diarrhea can be broken down into several categories, including:

• Viral infections, such as norovirus and rotavirus, which are the leading causes of acute gastroenteritis in the United States, with norovirus exceeding Salmonella enterica subspecies as a cause of illness, but Salmonella enterica subspecies exceeding norovirus as a cause of hospitalization and death 1
• Bacterial infections, such as Salmonella enterica subspecies, Campylobacter, Shigella, Yersinia, and E. coli O157, which are common bacterial pathogens that can cause diarrhea, particularly in children under 5 years old 1
• Food intolerances, such as lactose intolerance, which can trigger diarrhea in some individuals
• Medication side effects, such as antibiotics, antacids containing magnesium, and some cancer treatments, which can frequently cause diarrhea

Prevention and Management

Prevention and management of diarrhea can be achieved through:

• General measures, including use of hand hygiene, proper food preparation and storage, avoidance of high-risk foods, and avoidance of unsafe water 1
• Specific preventive measures, such as routine use of rotavirus vaccine in infants, and typhoid and cholera vaccines for travelers when indicated 1
• Treatment, which depends on the cause, but generally involves staying hydrated with water, clear broths, or oral rehydration solutions like Pedialyte, and over-the-counter medications like loperamide (Imodium) for mild cases, but avoiding these if fever or bloody stools are present 1

From the Research

Common Causes of Diarrhea

The most common causes of diarrhea can be attributed to various factors, including:

• Infectious pathogens, such as bacteria, viruses, and parasites, which are responsible for the majority of diarrhea cases worldwide 2, 3
• Bacterial causes, including Salmonella, Shigella, and Campylobacter, which are common causes of acute bacterial enteritis in the United States 4
• Lactose intolerance, which is caused by a reduction or loss of the activity of the intestinal enzyme lactase-phlorizin hydrolase, leading to abdominal pain, diarrhea, and flatulence 5, 6
• Food handling and distribution practices, which can lead to outbreaks of infectious diarrhea in developed countries 3
• Antibiotic use, which can disrupt the balance of gut flora and lead to diarrhea, particularly in the case of Clostridium difficile infection (CDI) 3

Infectious Causes

Infectious diarrhea is a significant cause of morbidity and mortality worldwide, especially in children, and is often caused by:

• Viral pathogens, such as rotavirus and norovirus
• Bacterial pathogens, such as Salmonella, Shigella, and Campylobacter
• Parasitic pathogens, such as Giardia and Cryptosporidium

Non-Infectious Causes

Non-infectious causes of diarrhea include:

• Lactose intolerance, which is characterized by abdominal pain, distension, borborygmi, flatus, and diarrhea induced by lactose in dairy products 5, 6
• Irritable bowel syndrome (IBS), which can be exacerbated by lactose intolerance and other dietary factors 6