Gastroenteritis in Adults and Older Children

Gastroenteritis in Adults and Older Children

Topic Overview

What is gastroenteritis?

Gastroenteritis is an upset stomach. It causes nausea and vomiting. You may also have diarrhea or a fever. It is sometimes called "stomach flu," but it is not the flu. Germs like viruses and bacteria can cause it.

You can catch it from someone else who has it, or you can get it from foodborne illness. Foodborne illness can happen if you eat foods that contain harmful germs. Germs can get into food while the food is growing, during processing, or when it is prepared. You may have become ill after eating meat or eggs that weren't cooked enough or by eating other unsafe foods or drinking unsafe water.

You will probably begin to feel better in 1 or 2 days, but you might feel bad for a week. In the meantime, get plenty of rest, and make sure you do not become dehydrated. Dehydration occurs when your body loses too much fluid. This can happen when you throw up a lot or have diarrhea.

What should you do at home?

    • Drink plenty of fluids. Choose water and other caffeine-free clear liquids until you feel better. If you have kidney, heart, or liver disease and have to limit fluids, talk with your doctor before you increase how much fluid you drink.
    • Drink fluids slowly, in frequent, small amounts. Drinking too much too fast can cause vomiting.
    • Electrolytes should also be replaced, especially if vomiting or diarrhea lasts longer than 24 hours. Electrolytes are minerals in your blood that keep many systems in your body working smoothly. If you have a long period of vomiting and diarrhea, you can lose minerals. Sports drinks, which contain a mix of salt, sugar, and minerals, may help replace electrolytes.
    • When you feel like eating, start with mild foods, such as dry toast, yogurt, applesauce, bananas, and rice. Avoid spicy, hot, or high-fat foods, and do not drink alcohol or caffeine for a day or two. 

When should you call a doctor?

You can usually take care of gastroenteritis at home.

  • But call 9-1-1 or other emergency services immediately if:
    • You have signs of severe dehydration. These include little or no urine; sunken eyes, no tears, and a dry mouth and tongue; fast breathing and heartbeat; feeling very dizzy or light-headed; and not feeling or acting alert.
    • You think you may have foodborne illness from a canned food and you have symptoms of botulism (blurred or double vision, trouble swallowing or breathing, muscle weakness).
  • Call your doctor immediately if:
    • Severe diarrhea (large amounts of loose stool every 1 to 2 hours) lasts longer than 2 days in an adult.
    • Vomiting lasts longer than 1 day in an adult.
    • You are pregnant and believe that you have been exposed to listeriosis or toxoplasmosis. For more information on toxoplasmosis, see the topic Toxoplasmosis During Pregnancy.
    • You have sudden, severe belly pain.
    • Your stools are black and tarry or they have streaks of blood.
  • Talk to your doctor if:
    • You have symptoms of mild dehydration (dry mouth or passing only a little urine) that get worse even with home treatment.
    • You have a fever that lasts more than 1 or 2 days.
    • You are not feeling better after 1 week of home treatment.

How can you prevent gastroenteritis?

The best thing you can do to keep from catching gastroenteritis from someone else is to make a habit of washing your hands often. This is especially important after you use the bathroom, after you change a baby's diaper, and before you eat or prepare food.

Don't share personal items like forks and spoons, toothbrushes, and towels. Try not to be around others who have stomach flu. Keep your hands away from your nose, eyes, and mouth.

You can prevent foodborne illness by taking steps to make sure your food is not contaminated:

    • Wash cutting boards and countertops often with hot, soapy water. Consider using disinfectant sprays or wipes on your counters.
    • Keep hot foods hot and cold foods cold.
    • Do not eat meats, dressings, salads, or other foods that have been kept at room temperature for more than 2 hours.
    • Use a thermometer to check your refrigerator. It should be between 1°C (34°F) and 4°C (40°F).
    • Defrost meats in the refrigerator or microwave, not on the kitchen counter.
    • Cook meat until it is well done.
    • Do not eat raw eggs or uncooked sauces made with raw eggs.
    • Do not take chances. If food looks or tastes spoiled, throw it out.
    • Be extra careful when you travel. In some countries, you may not want to drink water from the tap (including ice cubes) or eat any raw foods.


Adaptation Date: 9/19/2023

Adapted By: HealthLink BC

Adaptation Reviewed By: HealthLink BC