Patient Education1 min read

Gastroenteritis (Stomach Flu)

Overview

Gastroenteritis is an infection or inflammation of the stomach and intestines, most often caused by a virus and sometimes by bacteria or parasites. It typically causes sudden diarrhea, vomiting, and abdominal cramps, and most healthy adults recover within a few days. The main risk is losing too much body fluid, so staying hydrated is the most important part of care.

Symptoms

Watery diarrhea

Nausea and vomiting

Abdominal cramps and pain

Low-grade fever

Headache, muscle aches, and tiredness

Loss of appetite

Common Causes

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Viruses such as norovirus and rotavirus (the most common cause)

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Bacteria such as Salmonella, Campylobacter, and E. coli, often from contaminated food or water

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Parasites such as Giardia

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Close contact with an infected person or touching contaminated surfaces

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Undercooked meat, eggs, or unwashed produce

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Poor hand hygiene, especially after using the toilet or before eating

Self-Care Tips

Drink fluids often in small sips; oral rehydration solution (ORS) is the best choice

Resume eating as soon as you can tolerate it; you do not need to fast

Avoid very sugary drinks, energy drinks, and heavily fatty foods while recovering

Wash your hands with soap and water, as alcohol sanitizers are less effective against some germs such as norovirus

Rest at home and avoid preparing food for others until symptoms have settled

Do not take antibiotics or anti-diarrheal medicines unless a doctor advises it

When to See a Doctor

Seek medical care promptly if you see blood in the stool or vomit, have a high fever, cannot keep fluids down, or show signs of dehydration such as intense thirst, dark or very little urine, dizziness, or extreme weakness. Symptoms lasting more than 2 to 3 days also need evaluation. Infants, young children, older adults, pregnant women, and people with chronic illness or weakened immunity should be seen early.

How doctors assess it

Most cases are diagnosed from your history and a physical examination, with particular attention to signs of dehydration such as dry mouth, fast heart rate, and low blood pressure. Stool tests or blood tests are usually not needed for a mild illness. They are considered when symptoms are severe or prolonged, when there is blood in the stool, after recent travel or antibiotic use, or in people with weak immunity. Persistent or recurrent diarrhea may call for further evaluation to look for other digestive conditions.

Treatment options

Treatment focuses on replacing lost fluids and salts, ideally with oral rehydration solution, and on returning to a normal diet as soon as it is tolerated. Anti-nausea medicine may be used in some cases under medical advice. Anti-diarrheal medicines should be avoided if there is blood in the stool or high fever, and they are not suitable for young children. Severe dehydration may require intravenous fluids in a hospital or clinic, and antibiotics are used only for selected bacterial or parasitic infections.

Frequently Asked Questions

Do I need antibiotics for gastroenteritis?

Usually not. Most cases are caused by viruses, which do not respond to antibiotics, and even many bacterial infections clear on their own. Antibiotics are reserved for specific situations that your doctor will decide on, and using them unnecessarily can cause side effects.

What is the best way to rehydrate?

Oral rehydration solution, available at pharmacies, is designed to replace water and salts in the right balance. Take small, frequent sips, and pause for a few minutes if you vomit before starting again. Plain water, diluted juice, and broth can help, but juice, soda, and sports drinks alone are not ideal.

How long am I contagious, and how can I protect my family?

You can spread the infection while you have symptoms and often for a few days afterward, and sometimes longer. Wash hands thoroughly with soap and water, clean contaminated surfaces, wash soiled clothing separately, and avoid sharing towels and utensils. Stay away from work, school, or nursery until symptoms have stopped, as advised by your doctor.