Published: 18 Jun 2025

ICD9: 558.9      ICD10: K52.9      ICD11: 1A40.Z

Gastroenteritis, also commonly known as a stomach bug, is an inflammation of the stomach and intestines that causes diarrhea, vomiting, and stomach pain.
It's often referred to by its individual components as well:

Enteritis: Inflammation of the small intestine
Colitis: Inflammation of the colon (large intestine)
Gastroenteritis: Inflammation of both the stomach and the intestines

Causes:

Viral infections: These are the most common cause, especially norovirus and rotavirus.
Bacterial infections: Bacteria like Salmonella, E. coli, Campylobacter, and Shigella can cause gastroenteritis.
Parasites: Parasites like Giardia can cause gastroenteritis, particularly through contaminated water.
Food poisoning: Toxins produced by bacteria in contaminated food can cause gastroenteritis-like symptoms.
Medications: Some medications can irritate the stomach and intestines.
Chemicals: Exposure to certain chemicals can also cause gastroenteritis.

Symptoms:

Diarrhea (often watery)
Vomiting
Abdominal cramps and pain
Nausea
Fever
Loss of appetite
Headache
Muscle aches
Dehydration (especially in young children, the elderly, and people with weakened immune systems)

Transmission:

Gastroenteritis is highly contagious and can spread through:

Contact with infected people: Touching contaminated surfaces and then touching your mouth, nose, or eyes.
Contaminated food or water: Eating or drinking food or water that is contaminated with bacteria, viruses, or parasites.
Poor hygiene: Not washing hands thoroughly after using the toilet or before preparing food.

Treatment:

Most cases of gastroenteritis are mild and resolve on their own within a few days. The main focus of treatment is to prevent dehydration:

Drink plenty of fluids: Water, clear broths, electrolyte solutions (like Pedialyte), and diluted juices.
Eat bland foods: Start with small amounts of easily digestible foods like crackers, toast, bananas, and rice.
Rest: Allow your body to recover.
Avoid dairy products, caffeine, alcohol, and fatty foods: These can worsen symptoms.
Over-the-counter medications: Anti-diarrheal medications (like loperamide) and anti-emetics (anti-vomiting medications) may be used in some cases, but it's important to talk to your doctor or pharmacist before using them, especially for children.

When to See a Doctor:

You should seek medical attention if you experience any of the following:

Severe dehydration (signs include decreased urination, dizziness, extreme thirst, rapid heartbeat)
Bloody stool or vomit
High fever (over 101°F or 38.3°C)
Severe abdominal pain
Inability to keep down fluids
Symptoms lasting more than a few days
Underlying health conditions (diabetes, kidney disease, etc.)

Prevention:

Wash your hands frequently: Especially after using the toilet, before eating, and after being in contact with someone who is sick.
Practice safe food handling: Cook food thoroughly, store food properly, and avoid cross-contamination.
Drink safe water: If you are unsure about the safety of the water, boil it or use bottled water.
Get vaccinated: The rotavirus vaccine is available for infants and can help prevent rotavirus gastroenteritis.

In summary, gastroenteritis is an inflammation of the stomach and intestines, leading to a variety of unpleasant symptoms. While usually self-limiting, it's important to stay hydrated and seek medical attention if symptoms are severe or persistent.