What is the “stomach flu”?
People commonly call viral gastroenteritis “stomach flu,” but the term is not medically correct. Flu viruses do not cause viral gastroenteritis. Stomach flu is a viral infection that affects the stomach and small intestine. It is also called viral gastroenteritis. The illness is usually brief, lasting 1 to 3 days.
Many different viruses can cause stomach flu, including rotaviruses, adenoviruses, and the norovirus virus. Norovirus is the leading cause of foodborne illness in the United States and is a very contagious virus that causes vomiting and diarrhea.
People of all ages can get sick with norovirus. You can get norovirus by accidentally getting tiny particles of feces (poop) or vomit from an infected person in your mouth. There’s no vaccine to prevent norovirus infection and no drug to treat it.
The body fluids of infected people contain the virus, sometimes even before their symptoms begin. The virus can be spread by direct contact with an infected person. For example, you might get it by kissing or shaking hands or by sharing food, drink, or eating utensils.
The virus inflames the stomach and intestine. When the stomach and intestine are inflamed, they don’t work as well as they should. Food may move faster through your digestive tract.
What are the symptoms?
When you have stomach flu, you may have one or more of the following symptoms:
- stomach cramps
- mild fever
- loss of appetite
- muscle aches
The illness may develop over a period of hours, or it may suddenly start with stomach cramps, vomiting, or diarrhea.
Some bacteria, parasites, medicines, or other medical conditions can cause similar symptoms.
If your symptoms are unusually severe or last longer than a few days, your healthcare provider can determine if the diarrhea is caused by something other than a virus.
How is it diagnosed?
Your healthcare provider will ask about your symptoms. He or she will examine you. You may have lab tests to rule out more serious illnesses and to check for problems that can be caused by stomach flu, such as dehydration.
How is it treated?
The most important thing to do is to rest the stomach and intestine. You can do this by not eating solid food for a while and drinking only clear liquids. As your symptoms go away, you can start eating soft bland foods that are easy to digest.
If you have been vomiting a lot, it is best to have only small, frequent sips of liquids. Drinking too much at once, even an ounce or two, may cause more vomiting.
Your choice of liquids is important. If water is the only liquid you can drink without vomiting, that is OK. However, if you have been vomiting often or for a long time, you must replace the minerals, sodium and potassium, that are lost when you vomit. Ask your healthcare provider what sport drinks or other rehydration drinks could help you replace these minerals.
Other clear liquids you can drink are weak tea and apple juice. You may also drink soft drinks without caffeine (such as 7-UP) after letting them go flat (lose their carbonation). It may be easier to keep down liquids that are cold. Avoid liquids that are acidic (such as orange juice) or caffeinated (such as coffee) or have a lot of carbonation. Do not drink milk until you no longer have diarrhea.
You may start eating soft bland foods when you have not vomited for several hours and are able to drink clear liquids without further upset. Soda crackers, toast, plain noodles, gelatin, eggs, applesauce, and bananas are good first choices. Avoid foods that are acidic, spicy, fatty, or fibrous (such as meats, coarse grains, vegetables). Also avoid dairy products. You may start eating these foods again in 3 days or so, when all signs of illness have passed.
Sometimes treatment includes prescription medicine to prevent nausea and vomiting or diarrhea.
Nonprescription medicine is available for the treatment of diarrhea and can be very effective. If you use it, make sure you use only the dose recommended on the package. If you have chronic health problems, always check with your healthcare provider before you use any medicine for diarrhea.
How long do the effects last?
Stomach flu rarely lasts longer than 1 to 3 days. However, it may be 1 to 2 weeks before your bowel habits are completely back to normal.
Dehydration is a potentially serious complication of stomach flu. It can happen if your body loses too much fluid because you keep vomiting or having diarrhea. If you are severely dehydrated, you may need to be given fluids intravenously (IV). In children and older adults, dehydration can quickly become life threatening.
How can I take care of myself?
- Rest your stomach and intestines by following the suggested guidelines for your diet during the illness, but make sure you prevent dehydration by drinking enough liquids. Drink just small amounts or sips while you are having vomiting.
- Do not take aspirin, ibuprofen, or other nonsteroidal anti-inflammatory medicines (NSAIDS) without checking first with your healthcare provider.
- Call your healthcare provider if:
- Your symptoms are getting worse.
- You keep having severe symptoms (vomiting or frequent diarrhea) for more than 1 or 2 days, or you are just not getting better after a few days.
- You start having symptoms that are not usually caused by stomach flu, such as blood in your vomit, bloody diarrhea, or severe abdominal pain.
- Wash your hands with soap and water for at least 20 seconds. If soap and water are not readily available, you can use an alcohol-based hand sanitizer that contains at least 60% alcohol. You can tell if the sanitizer contains at least 60% alcohol by looking at the product label.
- When preparing food, carefully rinse fruits and vegetables and thoroughly cook shellfish, such as oysters.
- Do not prepare food or provide care for others when you are sick with norovirus and for at least 2 days after you feel better.
- Immediately clean and sanitize surfaces that have diarrhea or vomit on them. Use disposable gloves to wipe up vomit or diarrhea with paper towels. Next, use a bleach-based or other approved cleanerexternal icon on the surface. Then clean the surface again with hot water and soap.