How Long Do Stomach Viruses Last?

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

The stomach flu is a common illness that goes by many names—including stomach bug and viral gastroenteritis, which is the medical name. 

Most commonly, norovirus causes viral gastroenteritis. But other viruses, such as rotavirus (especially in children), adenovirus, sapovirus, and astrovirus, may also cause the illness.

Also, despite the name, the stomach flu doesn't have anything to do with influenza. But the illness can feel just as bad, or worse, than the flu. Between nausea, vomiting, diarrhea, and stomach cramps, if you've been there, you won't probably forget it.

Here's what you should know about viral gastroenteritis, including how long the illness typically lasts in adults.

How Long Before Stomach Flu Symptoms Start?

Viruses have an incubation period, the time between getting infected and having symptoms. Symptoms usually appear anywhere from within 12 hours to a few days after exposure to the virus. But in some cases, it can be longer than that.

If you have viral gastroenteritis, there is a good chance that the culprit is norovirus. Norovirus is the cause of most foodborne illnesses in the United States, causing nearly 58% of cases yearly.

Virus Incubation Periods

The incubation period varies depending on the type of virus that causes gastroenteritis, including:

  • Norovirus: This virus is extremely contagious. Usually, norovirus outbreaks occur in daycare centers, schools, hospitals, nursing homes, and cruise ships. You may start seeing symptoms about 12 to 48 hours after being infected.
  • Sapovirus: A norovirus-related virus, sapovirus also has a fairly short incubation period. If you have sapovirus, symptoms may appear anywhere from less than one day to four days later.
  • Rotavirus: This virus occurs mostly in children. Rotavirus has a longer incubation period than norovirus or sapovirus. Symptoms may not show up until about two days after being infected.
  • Astrovirus: This virus has an incubation period of four to five days.
  • Enteric adenovirus: This type of adenovirus affects your gut and has a long incubation period of eight to 10 days. So, it may be well after a week before symptoms appear if enteric adenovirus makes you ill.

Stomach Flu Symptoms

When it comes to symptoms, you won't be able to tell which of those viruses you caught. But norovirus and rotavirus cause more severe symptoms than other gastroenteritis-causing viruses. 

Some of the most common symptoms of stomach flu include:

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

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

Also, depending on the type of virus, the order that symptoms appear may differ. For example, if you have rotavirus, you will likely start vomiting before watery diarrhea and fever. Also, norovirus usually starts with vomiting and non-bloody diarrhea.

How Long Stomach Flu Symptoms Last

Some people with viral gastroenteritis don't have any symptoms. But if you have symptoms, there's a good chance that they will go away rather quickly. 

If you have a healthy immune system, symptoms most likely disappear within a few days. But you may need more time if you have a weak immune system.

Typically, the timelines for viral gastroenteritis symptoms depend on the specific virus, including:

  • Norovirus: Generally, norovirus clears up within a couple of days.
  • Sapovirus: Usually, sapovirus lasts a few days. Although, diarrhea may continue for up to a week.
  • Astrovirus: This virus should resolve within two to three days.
  • Rotavirus: This virus can last anywhere from three to eight days.
  • Enteric adenoviruses: In some cases, enteric adenovirus can take up to two weeks to resolve.

Recovery From Stomach Flu

Viral gastroenteritis is a self-limiting disease. In other words, you'll recover on your own without treatment. With viral gastroenteritis, your immune system is busy fighting the viral invader to help you feel normal. Those types of diseases also resolve spontaneously.

People with weak immune systems may have a harder time fighting the virus than normal. Their symptoms may last longer than normal, and they also have a high risk for complications.

Conditions that may worsen your chances of a quick recovery include:

  • Immunodeficiency syndromes
  • Inflammatory bowel disease (IBD)
  • Structural heart disease
  • Metabolic diseases, such as diabetes
  • Kidney disease
  • Autoimmune conditions, like rheumatoid arthritis and lupus

Talk to a healthcare provider if you have any of those conditions and develop viral gastroenteritis.

What To Do if You Get Stomach Flu

There's no cure for viral gastroenteritis. But there are some things you can do to ensure that you're on the right track to feeling normal. 

For example, one of the most important things to do is to stay hydrated. Because you lose a lot of fluid when you have diarrhea or are vomiting, you need to replace that fluid. 

Taking small sips throughout the day can help with difficulty drinking water. Staying hydrated will help you from getting dehydrated, a serious complication that may require hospitalization in severe cases.

Also, you're losing electrolytes, like sodium and potassium, which you should replace. Sports drinks may help replenish electrolytes. But pediatric electrolyte solutions are one of the best choices to replace lost electrolytes due to vomiting and diarrhea. Those solutions are also good for staying hydrated, even when you're not sick.

Dehydration can be particularly serious in children. So, if your child has viral gastroenteritis, be on the lookout for symptoms like:

  • Crying with few or no tears
  • Sunken eyes
  • Unusually drowsy, sleepy, or irritable

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

Over-the-counter (OTC) remedies that contain bismuth subsalicylate, like Pepto-Bismol, may help with 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 with a healthcare provider before taking them.

When To Call a Healthcare Provider

Usually, diarrhea and vomiting are not causes 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 Centers for Disease Control and Prevention (CDC) recommends seeking treatment for the following:

  • 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 include:

  • Uncontrollable vomiting
  • Bloody diarrhea
  • Pregnancy

A healthcare provider may want to do lab tests to know what virus is causing your symptoms.

How To Prevent Stomach Flu

Remember all those "wash your hands" signs in restaurant restrooms? They're there for a reason. You can get viral gastroenteritis from sewage-contaminated food, like leafy greens, fresh fruits, and shellfish, or water. Also, you may become ill if an infected person prepares your meal.

The viruses that cause viral gastroenteritis spread in the same ways. Often, the viruses spread through the fecal-oral route. In other words, the viruses can spread from feces to the mouth.

So, if viruses are on your hands, and you touch food that goes into your mouth or put your hands directly on your mouth, you can introduce the virus into your body. But with proper handwashing and hygiene, you can stop those viruses from spreading.

Norovirus lives in vomit or feces. The virus can even stay in feces for two weeks or more after you start feeling better. People with norovirus can shed billions of viral particles, and only a few can make you sick.

So, thoroughly washing your hands is important. Prime times to wash your hands include:

  • 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

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

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

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

Risk Factors for Stomach Flu

Young children's developing immune systems make fighting off viral infections harder than normal and increase their risk of dehydration.

People aged 65 years and older are also more prone to viral gastroenteritis. Older adults may need up to four days to recover.

Anyone living with a chronic illness—such as heart disease, asthma, cancer, kidney disease, and human immunodeficiency virus (HIV)—or taking immune system-suppressing medications may develop complications. Those people should see a healthcare provider if they have viral gastroenteritis.

What Else To Know About Stomach Flu

When you stop vomiting and your diarrhea subsides, you may feel very hungry. But waiting a few days before you celebrate with a feast is important. 

Overloading the stomach too soon may make you feel sick again. Skipping fatty foods and sticking to light, easy-to-digest meals in small portions will also help as you start to feel normal.

Remember that they shouldn't last long if you come down with stomach flu symptoms. 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.

A Quick Review

Many viruses cause gastroenteritis, commonly known as stomach flu. Depending on the type of virus, the incubation period, order of symptoms, length, and severity of your illness will vary. 

Your symptoms should start to go away within a few days. Talk to a healthcare provider if they don't or you have concerns about your health.

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