How Long Does the Stomach Flu Last?

Here's what to know about the stomach flu and how long symptoms can last.

rez-art/Getty Images

Despite the fact that it's so common, many people don't know much about the stomach flu. That's because it has many other names, including stomach bug and viral gastroenteritis (its actual medical term). Viral gastroenteritis is commonly caused by norovirus, but it can also be caused by other viruses, such as rotavirus (especially in children), adenovirus, sapovirus, and astrovirus.

The stomach flu doesn't have anything to do with the actual flu, which is caused by the influenza virus—but it can feel just as bad. Between the vomiting and diarrhea and stomach cramps...if you've been there, you won't forget it.

Here are some things to know about viral gastroenteritis, including how long it lasts in adults.

How Long Before Symptoms Start

Viruses have what is called an incubation period, which is how long it takes from the time you get infected until you may start to see symptoms. Symptoms usually appear anywhere from within half a day to a few days after exposure to the virus. But in some cases, it can be longer.

If you've got stomach flu, there is a good chance it was caused by norovirus. Norovirus is the number-one cause of foodborne illness in the US, causing 58% of foodborne illnesses in the US each year.

Norovirus is extremely contagious. It's usually what causes outbreaks in daycare centers, schools, hospitals, nursing homes, and cruise ships, just to name a few examples. If you're infected, you may start seeing symptoms about 12 to 48 hours later.

Sapovirus, a virus related to norovirus, also has a fairly short incubation period. If you've got sapovirus, symptoms may show up anywhere from less than one day to as many as four days later, a 2015 study reports.

Rotavirus occurs mostly in children. It has a longer incubation period than norovirus or sapovirus. Symptoms of gastroenteritis caused by this bug may not show up until about two days after you've been infected.

Another cause of stomach flu, astrovirus has an incubation period of four to five days.

Enteric adenovirus, the type of adenovirus that affects your gut, has an even longer incubation period of 8 to 10 days. So it may be well after a week before symptoms might appear if this is what is making you ill.

What Are the Symptoms?

When it comes to symptoms, they won't be able to tell you which of these bugs you caught. Even though norovirus and rotavirus cause more severe ones, the symptoms of stomach flu are all very similar:

  • Watery diarrhea
  • Nausea
  • Vomiting
  • Abdominal pain or cramping

Less common symptoms include a mild fever, chills, headache, muscle aches, and tiredness.

However, depending on the type of virus, the order in which symptoms appear may be different. If you've been infected with rotavirus, you will probably start vomiting before you have watery diarrhea and fever.

Norovirus also starts with vomiting and non-bloody diarrhea and can be accompanied by any of the other symptoms.

How Long Symptoms Last

Sometimes you may not have any symptoms if you catch one of these viruses. If you do have symptoms, however, there is a good chance that they will go away rather quickly. People with healthy immune symptoms will most likely see their symptoms disappear within a few days, but people with compromised immune systems may need longer.

Typical timelines for viral gastritis symptoms depend on the specific virus:

  • Norovirus: Generally clears up within a couple of days
  • Sapovirus: Usually lasts a few days, although diarrhea may continue for up to a week
  • Astrovirus: Should resolve within two to three days
  • Rotavirus: Can last anywhere from three to eight days
  • Enteric adenoviruses: Can take up to two weeks to resolve

The Road to Recovery

Viral gastroenteritis is a self-limiting disease. Self-limiting means you will recover on your own without needing treatment. Your body's immune system will be busy fighting the viral invader to get you back to feeling normal. These types of diseases can also be said to resolve spontaneously.

People with compromised immune systems will have a harder time fighting off the virus. This is why their symptoms may last longer and why they are at high risk for developing complications.

Some conditions may worsen your chances of a quick recovery. These include:

  • Immunodeficiency syndromes
  • Inflammatory bowel diseases
  • Structural heart diseases
  • Metabolic diseases like diabetes
  • Kidney diseases
  • Autoimmune conditions like rheumatoid arthritis and lupus

If you have any of these conditions and develop the stomach flu, talk to your healthcare provider.

What To Do if You Get Stomach Flu

While there is no specific cure for viral gastroenteritis, there are some things you can do to ensure that you're on the right track to feeling well again soon. The most important thing to do is to stay hydrated.

Because you lose a lot of fluid in your body when you have diarrhea or are vomiting, you need to replace that fluid. But remember that you're also losing sodium, potassium, and other minerals (known as electrolytes), which need to be replaced too.

If you have a hard time drinking a bunch of water all at once, you may find it easier to take sips often throughout the day. This will help you from getting dehydrated. Dehydration can be a serious complication of the stomach flu and may require hospitalization if it gets severe.

Sports drinks may help replenish the electrolytes. But the CDC says pediatric electrolyte solutions are better choices to replace lost electrolytes, nutrients, and minerals due to vomiting and diarrhea. (They are also good choices for simply staying hydrated, even when you're not sick.)

Dehydration can be particularly serious in kids, so be on the lookout for this in children with stomach flu. They might show the following symptoms if they're dehydrated:

  • Crying with few or no tears
  • Have sunken eyes
  • Be unusually drowsy, sleepy, or irritable

If you think you, your child, or someone you are looking after is severely dehydrated, get emergency help right away.

Over-the-counter remedies that contain bismuth subsalicylate (like Pepto-Bismol) may help with simple diarrhea. Antidiarrheal medications may also help ease cramps, but healthcare providers don't usually recommend them if you have bloody diarrhea or a high fever, so check in with a healthcare provider before taking them.

When To Call a Healthcare Provider

Diarrhea and vomiting on their own are probably not cause for alarm, but if you see blood in your stool or vomit, call a healthcare provider right away. You should also seek help if you experience other signs of serious dehydration, including:

In addition, the CDC recommends seeking treatment if:

  • Your symptoms aren't getting better after three days
  • You have prolonged vomiting that prevents you from drinking liquids
  • Your temperature spikes above 102 degrees Fahrenheit

Aside from severe dehydration, other reasons to get medical attention are:

  • Uncontrollable vomiting
  • Bloody diarrhea
  • Pregnancy
  • You have one or more of the medical conditions mentioned above

Even if it is just the stomach flu, a healthcare provider may want to do lab tests. Getting lab tests done is the only way to know for sure which culprit is causing your symptoms.

How To Prevent the Stomach Flu

Remember all those "wash your hands" signs in restaurant bathrooms? They're there for a reason. You can get viral gastroenteritis from sewage-contaminated food—like leafy greens, fresh fruits, and shellfish—or water or from meals prepared or handled by an infected person.

The viruses that cause stomach flu all spread in the same way. They are often transmitted through what is known as the fecal-oral route. That means the virus can spread from feces (poop) to the mouth.

In other words, if your hands are contaminated, and you touch food that goes into your mouth or touch your mouth directly, you can introduce the virus to your system. But with proper hand hygiene, you can stop these viruses from spreading.

Norovirus can be found in vomit or feces and can even stay in feces for two weeks or more after you start feeling better. It only takes a few virus particles to make you sick, and people who have norovirus can shed billions of particles.

So wash your hands thoroughly. Prime times to wash your hands are:

  • After using the restroom
  • After changing a diaper (especially if the child is sick)
  • Before preparing food
  • Before giving medicine to yourself or someone else

These viruses can also live on household surfaces like kitchen utensils, counters, and clothing. Take extra caution by:

  • Disinfecting surfaces
  • Carefully washing contaminated clothes or linens.
  • Using gloves to handle soiled laundry

And remember to wash your hands with soap and water after touching surfaces that may be contaminated.

Who's at the Greatest Risk of Getting Sick?

Young children's developing immune systems make it harder for them to fight off viral infections, and their smaller bodies are also at greater risk of becoming dehydrated.

People aged 65 years and older are also more prone to coming down with viral gastroenteritis and may need up to four days to recover, a 2019 study found.

Anyone with a chronic illness, such as heart disease, asthma, cancer, kidney disease, living with HIV, or taking medications that suppress the immune system, is at risk of developing complications and should see their healthcare provider if they come down with the stomach flu.

What Else To Know About Stomach Flu

When you stop vomiting, and your diarrhea subsides, you'll probably feel pretty hungry. But you may want to wait a few days before you celebrate with a feast. Overloading the stomach too soon may make you feel sick all over again. Skipping fatty foods and sticking to light, easy-to-digest meals in smaller portions will also help as you start to feel better.

Remember that if you come down with the signs of stomach flu, they shouldn't last long. You should expect to start feeling like your usual self again within a few days. But if your symptoms don't go away or you have other health concerns, you'll want to contact a healthcare provider.

Was this page helpful?
Sources uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. U.S. National Library of Medicine: MedlinePlus. Viral gastritis.

  2. Centers for Disease Control and Prevention. Burden of norovirus illness in the U.S.

  3. Cardemil CV, Hall AJ. Chapter 4: Travel-related infectious diseases–Norovirus. In: Kozarsky PE, Henry R, eds. CDC Yellow Book 2020: Health Information for International Travel. Oxford University Press; 2020.

  4. Oka T, Wang Q, Katayama K, Saif LJ. Comprehensive review of human sapoviruses. Clin Microbiol Rev. 2015;28(1):32-53. doi:10.1128/CMR.00011-14

  5. Centers for Disease Control and Prevention. Rotovirus: clinical information.

  6. Pérot P, Lecuit M, Eloit M. Astrovirus diagnostics. Viruses. 2017;9(1):10. doi:10.3390/v9010010

  7. Chiejina M, Samant H. Viral Diarrhea. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022. 

  8. Centers for Disease Control and Prevention. How you treat norovirus.

  9. U.S. National Library of Medicine: MedlinePlus. Dehydration.

  10. NIH: National Institute of Diabetes and Digestive and Kidney Diseases. Treatment for diarrhea.

  11. Centers for Disease Control and Prevention. Food poisoning symptoms.

  12. Centers for Disease Control and Prevention. Preventing norovirus.

  13. Cardemil CV, Parashar UD, Hall AJ. Norovirus infection in older adults: epidemiology, risk factors, and opportunities for prevention and control. Infect Dis Clin North Am. 2017;31(4):839–70. doi:10.1016/j.idc.2017.07.012

Related Articles