Stomach Flu Stages and Duration

By Terez Malka, MD
Medically reviewed
December 1, 2021

When the stomach flu hits, it can take you out of commission (and into the bathroom) for a few days straight.

This intestinal infection can cause pain and cramping in your stomach, nausea, vomiting, fever, and diarrhea.

But the stomach flu isn’t a flu, and it doesn’t infect your stomach: It’s a common name we use for viral gastroenteritis, a group of viral infections that occur in the intestines, not the stomach.

And they aren’t caused by influenza, or flu viruses—the most common cause of viral gastroenteritis is norovirus, causing 19 to 21 million cases of stomach flu in the U.S. each year.

But if you’re suffering from the stomach flu, you’re probably not worried about the name—you’re wondering how long it will last, and when you’ll feel better.

Most cases of viral gastroenteritis go away on their own in less than a week. In this article, I’ll go into a little more detail about what the stomach flu is—and what it isn’t—and the stages of the infection, including how long it should last.

I’ll also outline when you should talk to a doctor or other healthcare provider about your symptoms.

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What is the Stomach Flu?

The stomach flu, also known as viral gastroenteritis, is a viral infection that impacts the intestines.

There are several different viruses that can cause the stomach flu; the two most common are noroviruses and rotaviruses.

These viruses cause the lining of the intestines to become inflamed, leading to diarrhea, stomach cramps, nausea, vomiting, and more.

Though they can be incredibly painful and uncomfortable, symptoms typically can be treated at home and only last for a few days, though they sometimes last longer.  

The stomach flu is highly contagious, and is typically spread through contact with an infected person (by exchanging bodily fluids), or by eating or drinking contaminated food or beverages.

Unfortunately, there is no cure for the stomach flu, and antibiotics are ineffective when treating viruses.

Prevention is key when it comes to dealing with these viruses, so remember to wash your hands, keep your distance, disinfect hard surfaces, and keep items like cups, utensils, and towels to yourself if you’re sick. 

Types

There are a variety of different viruses that can cause the stomach flu, but the two most common are noroviruses and rotaviruses.

  • Noroviruses: These are the most common cause of stomach flu, accounting for 19-21 million cases per year in the U.S. Noroviruses are typically spread through contaminated food or water, but human-to-human transmission is also possible.
  • Rotaviruses: These are the most common cause of the stomach flu in children, as rotaviruses often spread when kids put their fingers or contaminated objects in their mouths. Adults with rotavirus may not show symptoms. 

Symptoms

Common symptoms of the stomach flu include:

Dehydration is the most common complication of viral gastroenteritis.

Dehydration can become dangerous quickly, especially in older adults and young children, so it’s important to drink plenty of fluids, and watch for symptoms like dry mouth, dizziness, and decreased urination. 

Diagnosis

If your stomach flu symptoms are mild and remain for a short period of time, you probably won’t need to see a doctor.

If you do, the doctor will likely have you describe your symptoms, and can typically diagnose viral gastroenteritis based on those alone.

If they’re still not sure—or want to rule out other, more serious illnesses—they may perform a medical history, physical exam, or stool test. 

Treatment

There is no cure for the stomach flu.

Antibiotics are ineffective against viruses.

Luckily, the stomach flu tends to go away on its own, and can typically be treated at home.

Be sure to get adequate rest and plenty of fluids.

If you have been vomiting a lot, take small, frequent sips of fluids—if you drink too much too fast, it may lead to more vomiting.

Clear liquids—like water, weak tea, and apple juice—are best.

Avoid carbonated and caffeinated beverages.

If you have been vomiting frequently, try to drink a sports or rehydration beverage to replace minerals, sodium, and potassium that you’ve lost. 

You should also avoid sugary, fatty, acidic, fibrous and spicy foods, as well as alcohol and dairy.

These can further irritate the stomach. 

There are a variety of over the counter (OTC) medications that can help ease symptoms until the virus has run its course.

These include anti-nausea medications, like Bismuth subsalicylate (Pepto Bismol), and antidiarrheals, like loperamide (Imodium).

If you have blood in your stool, a fever, or a chronic health condition, talk to your doctor before taking an antidiarrheal medication.

Stages of Stomach Flu

Stomach flu symptoms are typically short in duration, but you can be contagious before and after symptoms appear—depending on what type of virus you have (norovirus or rotavirus).

The stages of the stomach flu are as follows:  

Incubation Period

An incubation period is the time after you have caught an infection, but before you start noticing symptoms.

If you have norovirus, you’ll typically have an incubation period of one to two days.

You will not be contagious during this time.

If you contract rotavirus, your incubation period is typically one to three days, and you are contagious during this time.

Symptoms Appear

In most cases of stomach flu, symptoms typically come on quickly and severely, letting you know immediately that something is wrong.

Vomiting, diarrhea, and stomach cramps will probably be the first symptoms to appear.  

Symptoms Peak

For both norovirus and rotavirus, symptoms typically peak in the first day or two after they begin, and tend to be gone by the third day.

This can take longer for some people (up to 10 days), and certain symptoms may last longer than others.

Diarrhea, for example, has been known to last a few days longer than symptoms like vomiting, fever, and cramps. 

Recovery

With norovirus, you can be contagious for a few days after your symptoms go away, but the virus can remain in your stool for up to two weeks—so make sure you’re washing your hands thoroughly to avoid re-infection.

With rotavirus, you are contagious for up to two weeks after you’ve recovered. 

The best thing to do when you’re recovering from the stomach flu is to stay hydrated and stay mindful of others you are around.

Experts recommend staying home for at least 24-48 hours after your last symptom, and ensuring you don’t spread bodily fluids for a couple weeks.

Also be sure to clean surfaces that may be contaminated with the virus like counters, toilets, towels, and sheets. 

How Long Does the Stomach Flu Last?

Though it can feel endless, the worst part of the stomach flu rarely lasts longer than one to three days.

However, symptoms can sometimes last for up to 10 days, and it can take a few weeks for your bowel habits to return to normal.

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When to See a Doctor

Generally, the stomach flu can be treated at home with rest, plenty of fluids, and OTC medications.

However, there are a few cases where you should call a medical professional. 

If you are an adult, seek immediate care if:

  • You have blood in your vomit or bowel movements
  • You have been vomiting or having frequent diarrhea for more than two days 
  • You have not been able to keep down fluids for more than 24 hours or are seeing signs of dehydration

You should seek immediate care for an infant or child if:

  • They are abnormally irritable, or seem to be in pain
  • They have blood in their diarrhea
  • They vomit for more than several hours and are unable to keep any liquids in (note: vomit and a baby’s spit up are different things)
  • They appear dehydrated (for example: if they cry without tears, have a dry mouth, or haven’t had a wet diaper in six or more hours)
  • They have a sunken soft spot (fontanelle) on the top of their head
  • They appear lethargic

How K Health Can Help

Sometimes, when you’re dealing with something like the stomach flu, you just want to get a doctor’s advice. Did you know you can get affordable primary care with the K Health app?

Download K Health to check your symptoms, explore conditions and treatments, and if needed text with a doctor in minutes. K Health’s AI-powered app is HIPAA compliant and based on 20 years of clinical data.

Frequently Asked Questions

What is the fastest way to cure a stomach bug?
Though there’s no real cure for a stomach bug, there are some ways to treat symptoms to make you feel better, quicker. For example, you should be sure to stay hydrated (but avoid carbonated, caffeinated, and sugary beverages); eat mild, bland foods (avoiding fatty and sugary foods); and take an over-the-counter diarrhea medication, like loperamide (Imodium) to treat frequent diarrhea (as long as you’re an adult with no fever and no blood in your stool).
How long should someone stay home after being infected with the stomach flu?
Experts recommend staying home for at least 24-48 hours after your last symptom, and ensuring you don’t spread bodily fluids for a couple weeks. The stomach flu is contagious. Be thoughtful about when you go back out in public after becoming infected with it. If you have norovirus, you can be contagious for a few days after you recover. If you have rotavirus, you can be contagious for up to two weeks after you’ve recovered.
Do you need to bleach surfaces after having a stomach bug?
Yes. You can catch the stomach flu by touching contaminated surfaces, so it’s a great idea to disinfect surfaces in your home after having the stomach flu—especially if you’ve had diarrhea or vomiting. The CDC recommends using a bleach-based household cleaner, as some alcohol-based cleaners can be ineffective against some viruses. If you’re making your own bleach solution, use 5 to 25 tablespoons of household bleach [5% to 8%] per gallon of water, per the CDC.

K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Terez Malka, MD

Dr. Terez Malka is a board-certified pediatrician and emergency medicine physician.