7 Symptoms of Stomach Flu: Transmission & Treatment

Have you ever had the “stomach flu1 ?” What you probably had was gastroenteritis – not a type of flu at all. Gastroenteritis is an inflammation of the lining of the intestines caused by a virus, bacteria or parasites. Viral gastroenteritis is the second most common illness in the U.S.

Acute gastroenteritis (AGE; defined as diarrhea or vomiting) is a leading cause of illness in the United States; an estimated 179 million episodes2 occur annually. AGE is caused by a variety of viral, bacterial, and parasitic pathogens and by toxins, chemicals, and other noninfectious causes. Noroviruses are the leading cause of epidemic gastroenteritis, detected in ≈50% of AGE outbreaks across Europe and the United States. 

Noroviruses3 are a group of related viruses. Infection with these viruses causes an illness called gastroenteritis, an inflammation of the stomach and intestines. It can spread from person to person, or through contaminated food or water. You can also get it if you touch a contaminated surface. Norovirus can be severe, especially for young children and older adults.

Symptoms4 of Norovirus

Norovirus causes inflammation of the stomach or intestines or both. This is called acute gastroenteritis.

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The most common symptoms of norovirus infection are—

  1. diarrhea
  2. throwing up
  3. nausea
  4. stomach pain

Other symptoms—

  1. fever
  2. headache
  3. body aches

A person usually develops symptoms 12 to 48 hours after being exposed to norovirus. Most people with norovirus illness get better within 1 to 3 days.

7 Symptoms of Stomach Flu: Transmission & Treatment

Norovirus can spread quickly in closed places like daycare centers.

If you have norovirus illness, you can feel extremely ill and throw up or have diarrhea many times a day. This can lead to dehydration, especially in young children, older adults, and people with other illnesses.

Symptoms of dehydration—

  • Decrease in urination
  • dry mouth and throat
  • feeling dizzy when standing up

How is Norovirus Spread (Transmission)?

Norovirus is a highly contagious virus. Anyone can get infected with norovirus and get sick. Also, you can get norovirus illness many times in your life. One reason for this is that there are many different types of noroviruses. Being infected with one type of norovirus may not protect you against other types.

Norovirus can be found in your stool (feces) even before you start feeling sick. The virus can stay in your stool for 2 weeks or more after you feel better.

You are most contagious

  • when you are sick with norovirus illness, and
  • during the first few days after you recover from norovirus illness.

You can become infected with norovirus by accidentally getting stool or vomit from infected people in your mouth. This usually happens by

  • eating food or drinking liquids that are contaminated with norovirus,
  • touching surfaces or objects contaminated with norovirus then putting your fingers in your mouth, or
  • having contact with someone who is infected with norovirus (for example, caring for or sharing food or eating utensils with someone with norovirus illness).

Norovirus can spread quickly in closed places like daycare centers, nursing homes, schools, and cruise ships. Most norovirus outbreaks happen from November to April in the United States.

7 Symptoms of Stomach Flu: Transmission & Treatment

Norovirus outbreaks can also occur from foods, such as oysters, fruits, and vegetables.

Norovirus and food

Norovirus is the leading cause of illness and outbreaks from contaminated food5 in the United States. Most of these outbreaks occur in the food service settings like restaurants. Infected food workers are frequently the source of the outbreaks, often by touching ready-to-eat foods, such as raw fruits and vegetables, with their bare hands before serving them. However, any food served raw or handled after being cooked can get contaminated with norovirus.

Norovirus outbreaks can also occur from foods, such as oysters, fruits, and vegetables, that are contaminated at their source.


There is no specific medicine to treat people with norovirus illness. Norovirus infection cannot be treated with antibiotics because it is a viral (not a bacterial) infection.

If you have norovirus illness, you should drink plenty of liquids to replace fluid lost from throwing up and diarrhea. This will help prevent dehydration.

Sports drinks and other drinks without caffeine or alcohol can help with mild dehydration. But, these drinks may not replace important nutrients and minerals. Oral rehydration fluids that you can get over the counter are most helpful for mild dehydration.

Dehydration can lead to serious problems. Severe dehydration may require hospitalization for treatment with fluids given through your vein (intravenous or IV fluids). If you think you or someone you are caring for is severely dehydrated, call the doctor.

Preventing6 Norovirus Infection

Practice proper hand hygiene

Wash your hands carefully with soap and water—

7 Symptoms of Stomach Flu: Transmission & Treatment

Wash your hands thoroughly with soap and water to prevent Norovirus.

  • especially after using the toilet and changing diapers, and
  • always before eating, preparing, or handling food.

Wash fruits and vegetables and cook seafood thoroughly

Carefully wash fruits and vegetables before preparing and eating them. Cook oysters and other shellfish thoroughly before eating them.

Be aware that noroviruses are relatively resistant. They can survive temperatures as high as 140°F and quick steaming processes that are often used for cooking shellfish.

Food that might be contaminated with norovirus should be thrown out.

Keep sick infants and children out of areas where food is being handled and prepared.

Please remember that “The Stomach Flu” is often caused is by a norovirus infection. It spreads through contaminated food or water, and contact with an infected person. The best prevention is frequent hand washing.

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  1. https://vsearch.nlm.nih.gov/vivisimo/cgi-bin/query-meta?v%3Aproject=medlineplus&v%3Asources=medlineplus-bundle&query=stomach+flu&_ga=1.20600122.363795769.1476535848
  2. https://wwwnc.cdc.gov/eid/article/19/8/13-0482_article
  3. https://medlineplus.gov/norovirusinfections.html
  4. https://www.cdc.gov/norovirus/about/symptoms.html
  5. https://www.cdc.gov/norovirus/about/transmission.html
  6. https://www.cdc.gov/norovirus/preventing-infection.html

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