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Is the Stomach Flu Contagious?

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Is the Stomach Flu Contagious?

writtenByWritten by: Courtney Bennett
Courtney Bennett

Courtney Bennett

Courtney aims to simplify the complexities of modern medicine, enabling readers to make informed choices about their health. Her interests include reading, camping, hiking, painting, and photography.

Read more posts by this author.

February 24, 2021 Read Time - 9 minutes

What Is the Stomach Flu?

Stomach flu is the common term for a viral infection of the digestive tract (stomach and intestines) called viral gastroenteritis. While they share a common name, the stomach flu is not related to the flu caused by the influenza virus. When a person develops the stomach flu, the infection causes inflammation in the stomach and intestines, which causes the intense gastrointestinal distress that sends you running to the restroom.

The stomach flu is a highly contagious condition that is easily spread to others. While most individuals are able to recover quickly, the stomach flu can be particularly dangerous for vulnerable populations such as the very young, the elderly, and individuals with a compromised immune system.

Read on to learn how you can identify and prevent stomach flu spread.

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Viral Infections vs. Bacterial Infections

It is worth noting the differences between viral gastroenteritis and bacterial gastroenteritis. 

  • Bacterial gastroenteritis is caused by bacteria such as salmonella, E. coli, and C. difficile. 
  • While bacterial gastroenteritis presents similarly to viral gastroenteritis, it is far less common.

Viruses are different from bacteria in a few ways: they are smaller than bacteria, they cannot survive without a host, and most viruses cause disease. Most importantly, viruses cannot be treated with antibiotics. Alternatively, most bacteria are harmless, they can survive and reproduce independently, and the small percentage that causes the disease can be treated with antibiotics.

What Causes the Stomach Flu?

A number of different, highly contagious viruses cause the stomach flu. The most common types of viruses that cause the stomach flu are:


Norovirus is the most common cause of viral gastroenteritis in the United States. Unfortunately, the body is unable to build up an immunity to norovirus, so it is possible to come down with this type of stomach flu many times in your life.

Once exposed to norovirus, a person can usually start to see symptoms within 12 to 48 hours. In most cases, individuals infected with norovirus illness have their symptoms resolve within 1 to 3 days.


Sapovirus, which is in the same virus family as norovirus, can also cause the stomach flu. Due to their similarity and shared family, the two viruses are often studied in tandem. They are indistinguishable from each other without advanced testing as the symptoms are nearly identical. As diagnostic tools have been improving, sapovirus is increasingly being implicated in stomach flu cases.


Rotavirus is most likely to infect infants and young children, although it can be transmitted to anyone of any age. A spike in the number of rotavirus infections in children is often seen during the cooler weather of the winter and spring months (December through June). 

The Centers for Disease Control recommends the rotavirus vaccine to protect your children. While it is not 100% successful at preventing the stomach flu, 9 out of 10 children who receive the vaccine will avoid severe symptoms, and 7 out of 10 children will not come down with the infection at all.

Adults who get rotavirus usually have milder symptoms. Once a person has been exposed to rotavirus, it will take 1-3 days for the symptoms to appear.


Astrovirus is part of a relatively new virus family – most research on it has taken place in the past couple of decades, and it has only recently begun being recognized as a common cause of the stomach flu.

Astrovirus infections typically cause symptoms to present 3-4 days after infection, which is a significantly higher incubation period than norovirus and rotavirus and can therefore make it harder to trace the source of infection. Similar to rotavirus, astrovirus infections tend to spike in the winter months. Occasionally, persistent gastroenteritis can occur.

What are the Symptoms of the Stomach Flu?

While symptoms of stomach flu can differ from person to person based on the severity of the infection, most people will experience the same general suite of symptoms.

Symptoms of the stomach flu include:

  • Copious loose stool/watery diarrhea
  • Nausea and vomiting
  • Loss of appetite
  • Abdominal cramping

Less common symptoms:

  • Muscle aches
  • Headaches
  • Chills
  • Low-grade fever
  • Fatigue

Symptoms such as bloody diarrhea and high fever may indicate a more serious infection type.

How Long Does Stomach Flu Last?

The duration of symptoms depends on the type of virus that caused the initial infection. The stomach flu can last from one day to several weeks. The accompanying symptom duration also depends on what kind of virus is causing it. 

Read: Stomach Virus Signs, Symptoms, and Treatments

How Long Are You Contagious With The Stomach Flu?

Once you have identified that you have the stomach flu, you may wonder how long you are contagious. It depends on what virus you are infected with.  

People who contract the stomach flu from norovirus or rotavirus are contagious from when they begin feeling sick and for the first few days after they recover. Some people may be contagious for even longer. Norovirus can be found in your stool even before you start feeling sick. The virus can stay in your stool for two weeks or more after you feel better.

The viruses that cause the stomach flu can survive for several days on flat, hard surfaces. As a result, rotavirus can be easily spread in your household. There is also a potential for outbreaks to occur in childcare centers and playgroups once one child is infected.

Other common outbreak locations include cruise ships, nursing homes, and hospitals. Considering the stomach flu is so contagious, these environments’ confined and crowded nature allows the viruses to thrive.

Is A Stomach Bug Contagious Without Fever?

Yes. Even if you do not have a fever, you can still spread the stomach flu. If you have no symptoms at all yet, you can still spread the infection. 

How Does Stomach Flu Spread?

The stomach flu is spread through the fecal-oral route, in other words, when someone does not wash their hands after using the bathroom. You can pass the stomach flu to another person with direct contact or touch something with fecal matter on it. You cannot catch the stomach flu from the air; you must directly touch something. 

Common paths for transmission include:

  • Eating food or drinking water that has been contaminated
  • Touching surfaces or objects contaminated and then putting your fingers in your mouth – this is particularly common with small children, and why outbreaks in daycare centers can happen so easily
  • Having contact with someone who is infected (for example, caring for a sick child or kissing an ill spouse) and not properly washing your hands before eating or drinking
  • Sharing food or utensils with someone who is infected

How to Prevent the Spread of a Contagious Stomach Flu

To combat spreading the virus, if you suspect you or your child may have the stomach flu, you should do your best to stay home and rest. Your child should be kept home from school in order to avoid causing an outbreak. You should also avoid preparing foods. The number one key is to wash hands regularly and thoroughly.

While many healthcare sites recommend using hand sanitizer in addition to washing your hands, it is essentially useless against norovirus. The structure of the virus is incredibly unique. It has an outer shell that allows it to break down the alcohol used in hand sanitizers. 

An alarming study conducted by David Blaney, MD, Ph.D., from the Centers for Disease Control and Prevention in Atlanta, Georgia identified several risk factors for an outbreak, and the most significant risk factor identified was the use of alcohol-based hand sanitizers as often, or more often, than soap and water.

Once the infection has passed, clean and disinfect surfaces that could have gotten contaminated with a bleach-based household cleaner. A cleaning solution can be made at home by mixing a small amount of pure bleach with a large amount of water.

It is also important to immediately wash all potentially contaminated clothing and bedding. If possible, put clothing directly into the washing machine as you undress – storing the clothes in a laundry hamper allows the virus to contaminate the hamper, which are usually difficult to clean. When washing the infected items, you should use the longest cycle time available and be sure to dry the clothing in a dryer on high heat.

Diagnosis and Treatments for the Stomach Flu

The stomach flu can be diagnosed by your primary care physician or any general practitioner by taking a careful medical history. There are no tests done to confirm the stomach flu infection’s existence, partly due to the viruses’ diversity that can cause the infection. Occasionally, stool studies are requested to exclude other kinds of infections when symptoms are particularly severe.

Since antibiotics are not effective against the viruses that cause the infection, they should not be taken. Your doctor can prescribe over-the-counter medications to soothe symptoms and manage discomfort. 

These medications may include:

  • Ibuprofen or acetaminophen for fever and muscle aches. Acetaminophen tends to have fewer side effects and is less likely to irritate the stomach further.
  • Loperamide hydrochloride (Imodium) for the treatment of diarrhea.
  • Bismuth subsalicylate (Pepto-Bismol) for the treatment of nausea and diarrhea.

However, the most crucial part of stomach flu treatment is staying well hydrated, preferably with a drink that contains electrolytes. In addition, some people find that ginger or peppermint tea can help to combat nausea.

On top of refueling your body with electrolytes, it is essential to drink water, rest, and eat healthy meals. Keep your water bottle full, and stay away from strenuous activity.

  • Book on our free mobile app or website.

    Our doctors operate in all 50 states and same day appointments are available every 15 minutes.

  • See a doctor, get treatment and a prescription at your local pharmacy.

  • Use your health insurance just like you normally would to see your doctor.


When to See Your Doctor

While stomach flu will generally resolve itself without treatment, there is potential for extreme cases to cause severe dehydration. It is important to contact a doctor if you cannot keep liquids down, have been vomiting more than two days, develop bloody stools or a high fever, or are showing signs of severe dehydration.

Symptoms of severe dehydration:

  • Decrease in urination or dark urine
  • Dry mouth and throat
  • Dizziness or weakness
  • In children and infants: crying with few or no tears

Worrying about spreading any sort of illness is natural, but if you stay vigilant and use common sense, you should have no problem maintaining your health and the health of those around you. If you think you may have the stomach flu, consult your doctor or visit an urgent care center as soon as you can.

Book an appointment with an online doctor with PlushCare to get diagnosis confirmation, immediate treatment, and stomach flu medicine. 
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Read More About Stomach Flu 


PlushCare is dedicated to providing you with accurate and trustworthy health information.

CDC. General Information about Norovirus. Accessed on January 22, 2021.

Cleveland Clinic. Viral gastroenteritis (stomach flu). Accessed on February 14, 2021.

Orenstein R. (2020). Gastroenteritis, Viral. Encyclopedia of Gastroenterology, 652–657. Accessed on February 14, 2021.

Most PlushCare articles are reviewed by M.D.s, Ph.Ds, N.P.s, nutritionists and other healthcare professionals. Click here to learn more and meet some of the professionals behind our blog. The PlushCare blog, or any linked materials are not intended and should not be construed as medical advice, nor is the information a substitute for professional medical expertise or treatment. For more information click here.

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