Viral gastroenteritis, commonly called the stomach flu, is an infection that causes inflammation in your stomach and intestines. Despite its nickname, it’s not actually related to influenza (the flu). This common illness affects millions of people each year and can make you feel miserable for several days.

The main symptoms include diarrhea, vomiting, stomach cramps, and sometimes fever. While unpleasant, most people recover within a few days without needing medical treatment.

What Causes Viral Gastroenteritis

Several different viruses can cause stomach flu. The infection spreads easily from person to person, especially in crowded places like schools, daycare centers, and nursing homes.

Main Viruses That Cause Stomach Flu

The most common viruses include:

Norovirus

Norovirus is the leading cause of viral gastroenteritis worldwide. It accounts for about 18% of all gastroenteritis cases globally (1). The virus spreads through contaminated food, water, surfaces, and close contact with infected people. Symptoms typically appear within 12 to 48 hours of exposure.

Rotavirus

Before vaccines became available, rotavirus was the most common cause of severe diarrhea in young children. The virus primarily affects infants and children under 5 years old. In Africa, rotavirus vaccination programs have been highly successful in reducing cases (2).

Adenovirus

Adenoviruses cause about 10% of gastroenteritis cases in children worldwide (3). These viruses can cause diarrhea, along with respiratory symptoms. Adenovirus affects people of all ages but is more common in children under 2 years old.

Astrovirus

Astrovirus typically causes milder symptoms than other viruses and mainly affects young children, the elderly, and people with weakened immune systems.

How Stomach Flu Spreads

You can catch viral gastroenteritis by:

  • Having close contact with someone who’s infected
  • Eating contaminated food or drinking contaminated water
  • Touching contaminated surfaces and then touching your mouth
  • Not washing your hands properly after using the bathroom

The viruses that cause stomach flu are highly contagious. You can spread the infection even before you start feeling sick and for several days after you feel better.

Common Symptoms

Symptoms usually start 1 to 3 days after you’re exposed to the virus. They can range from mild to severe.

Main Symptoms

The most common symptoms include:

  • Watery diarrhea (usually non-bloody)
  • Nausea and vomiting
  • Stomach cramps and pain
  • Low-grade fever
  • Headache
  • Muscle aches

Dehydration Warning Signs

The biggest risk with stomach flu is dehydration. Watch for these warning signs:

  • Dry mouth and extreme thirst
  • Little or no urination
  • Dark yellow urine
  • Dizziness or lightheadedness
  • Weakness or fatigue
Warning
Seek medical care immediately if you have signs of severe dehydration, bloody diarrhea, high fever (over 102°F), or symptoms that last more than a few days.

Who Gets Viral Gastroenteritis

Anyone can get stomach flu, but some people are at higher risk of severe illness.

High-Risk Groups

People most at risk for complications include:

  • Infants and young children
  • Older adults
  • People with weakened immune systems
  • Pregnant women
  • People who are malnourished, especially those with low vitamin A or zinc levels

In Sudan, research found that viral diarrhea affected 22.90% of children under five years old (4).

Children are especially vulnerable because they:

  • Put their hands in their mouths frequently
  • Have developing immune systems
  • Spend time in group settings like daycare

Treatment Options

There’s no specific cure for viral gastroenteritis. Treatment focuses on managing symptoms and preventing dehydration.

Home Care

Most people can recover at home with these simple steps:

  • Rest as much as possible
  • Drink plenty of clear fluids
  • Start with small sips and gradually increase
  • Try oral rehydration solutions
  • Avoid solid foods until vomiting stops

Medical Treatments

For children with severe symptoms who come to the emergency room, medications can help. A study found that ondansetron (a medication that stops vomiting) can significantly help children with viral gastritis. It improved their ability to drink fluids and reduced hospital admissions from 20.5% to just 4.4% (5).

Over-the-Counter Medications

Adults can take certain over-the-counter medicines to help with symptoms:

Loperamide (Imodium)

Loperamide helps reduce diarrhea by slowing down bowel movements. Studies show it works better than bismuth subsalicylate at reducing the number of loose stools (6).

Bismuth Subsalicylate (Pepto-Bismol)

Bismuth subsalicylate can help with both diarrhea and stomach upset. Research shows it can reduce symptoms of viral gastroenteritis, particularly abdominal cramps (7).

Warning
Never give loperamide or bismuth subsalicylate to children without talking to a doctor first. These medications can be unsafe for infants and young children.
Tip
If your child can’t keep fluids down, ask your doctor about anti-nausea medication. It could help them avoid a hospital stay.

Probiotics May Help

Probiotics are beneficial bacteria that can help restore balance in your gut. Research shows they can be effective for viral gastroenteritis. A review of 17 studies with over 3,000 patients found that probiotics can:

  • Reduce diarrhea duration by about 0.7 days
  • Shorten hospital stays by about 0.76 days

(8)

Foods to Eat and Avoid

What you eat and drink during stomach flu can make a big difference in how you feel.

Best Foods During Recovery

Start with bland, easy-to-digest foods:

  • Plain rice
  • Toast or crackers
  • Bananas
  • Plain chicken or turkey
  • Clear broths
  • Applesauce

Worst Foods to Avoid

Some foods can make your symptoms worse and should be avoided:

  • Dairy products: Milk, cheese, and ice cream can be hard to digest
  • Fatty or fried foods: These can upset your stomach more
  • Spicy foods: Can irritate your digestive system
  • Caffeine: Coffee and sodas can worsen dehydration
  • Alcohol: Dehydrates you and irritates your stomach
  • Sugary drinks: Can make diarrhea worse
  • Raw vegetables: Hard to digest when your stomach is upset
  • Citrus fruits: The acid can irritate your stomach
Note
The BRAT diet (bananas, rice, applesauce, toast) is often recommended, but don’t limit yourself to just these foods. Add other bland foods as you feel better to get proper nutrition.

Staying Hydrated

Dehydration is the main concern with stomach flu. Your body loses fluids quickly through vomiting and diarrhea.

Best Fluids to Drink

Choose clear liquids that are easy on your stomach:

  • Water (small sips at first)
  • Oral rehydration solutions (like Pedialyte)
  • Clear broths
  • Electrolyte drinks (avoid ones high in sugar)
  • Herbal tea (ginger or peppermint)
  • Ice chips or popsicles

How to Rehydrate Properly

Follow these tips to keep fluids down:

  • Start with just a tablespoon every few minutes
  • Gradually increase the amount as tolerated
  • Drink fluids at room temperature
  • Avoid gulping large amounts at once

Diagnosis of Viral Gastroenteritis

Most cases of stomach flu are diagnosed based on symptoms alone. However, in some cases, doctors may need to do tests to confirm the virus or rule out other causes.

When Testing Is Needed

Your doctor might order tests if:

  • Symptoms are severe or prolonged
  • You’re at high risk for complications
  • There’s an outbreak being investigated
  • The diagnosis is unclear

Types of Tests

The most common test is a stool sample analysis. Modern testing uses molecular methods called PCR (polymerase chain reaction) to detect viruses. These tests can identify multiple viruses at once from a single stool sample (9).

PCR testing is much more sensitive than older methods. It can detect:

  • Norovirus
  • Rotavirus
  • Adenovirus
  • Astrovirus
  • Sapovirus

In some cases, rectal swabs can be used instead of stool samples. Research shows they’re just as reliable for detecting viruses in patients with recent symptoms (10).

Prevention Tips

You can reduce your risk of getting stomach flu by following good hygiene practices.

Hand Washing

Proper hand washing is your best defense:

  • Wash hands with soap and water for at least 20 seconds
  • Wash after using the bathroom
  • Wash before eating or preparing food
  • Use hand sanitizer if soap isn’t available

Rotavirus Vaccine

A vaccine is available to protect against rotavirus, one of the main causes of severe diarrhea in young children. The vaccine is highly effective:

  • In countries with low child mortality, the vaccine is 86% effective in the first year (11)
  • In Africa, rotavirus vaccination has reduced cases from 42% before vaccination to 21% after (2)

The rotavirus vaccine is given to infants as part of the routine vaccination schedule. It has significantly reduced hospitalizations and deaths from rotavirus worldwide.

Fact
Before the rotavirus vaccine, almost all children got rotavirus by age 5. Now, severe rotavirus disease is much less common in countries with vaccination programs.

Food Safety

Be careful with food preparation:

  • Wash fruits and vegetables thoroughly
  • Cook seafood completely
  • Avoid raw or undercooked foods when traveling
  • Don’t prepare food for others when you’re sick

Cleaning and Disinfecting

Keep your environment clean:

  • Disinfect contaminated surfaces immediately
  • Use bleach-based cleaners for best results
  • Wash contaminated clothing in hot water
  • Don’t share towels or eating utensils
Fact
Stomach flu viruses can survive on surfaces for days. Regular cleaning and disinfecting can help prevent the spread of infection in your home.

When to See a Doctor

Most cases of stomach flu get better on their own. But sometimes you need medical help.

For Adults

See a doctor if you have:

  • Symptoms lasting more than 3 days
  • Severe dehydration
  • Blood in vomit or stool
  • High fever (over 102°F)
  • Severe abdominal pain
  • Signs of shock (rapid heartbeat, dizziness)

For Children

Take your child to the doctor if they have:

  • Signs of dehydration (dry mouth, no tears when crying)
  • Unusually drowsy or unresponsive
  • Blood in their stool
  • High fever
  • Vomiting for more than several hours
  • Severe abdominal pain

Recovery Timeline

Understanding what to expect can help you plan for recovery.

Typical Duration

Most people feel better within:

  • 1-3 days for mild cases
  • 3-5 days for moderate cases
  • Up to 10 days for severe cases

Returning to Normal Activities

Wait to return to work or school until:

  • You’ve had no fever for 24 hours
  • Vomiting and diarrhea have stopped
  • You feel strong enough for normal activities

Remember that you can still spread the virus for a few days after you feel better. Continue practicing good hygiene.

Special Considerations

Some situations require extra care when dealing with stomach flu.

Stomach Flu vs. Food Poisoning

It can be hard to tell the difference:

  • Stomach flu: Symptoms start 1-3 days after exposure
  • Food poisoning: Symptoms usually start within hours
  • Stomach flu: Often includes fever and body aches
  • Food poisoning: May have more severe vomiting

Complications in Special Cases

People with weakened immune systems face additional risks. For example, in heart transplant patients, cytomegalovirus (CMV) can cause gastritis along with other complications. Studies show this affects a significant number of transplant recipients (12).

Summary
Viral gastroenteritis is unpleasant but usually resolves on its own. Focus on staying hydrated, rest, and gradually return to normal foods. See a doctor if symptoms are severe or don’t improve within a few days.

Frequently Asked Questions

Can I take antibiotics for stomach flu?

No, antibiotics don’t work against viruses. They’re only effective against bacterial infections. Taking antibiotics unnecessarily can cause side effects and contribute to antibiotic resistance.

How long am I contagious?

You can spread the virus from the moment you feel sick and for up to 2 weeks after recovery. Some people can spread the virus even before symptoms start.

Can I get stomach flu more than once?

Yes, you can get stomach flu multiple times. There are many different viruses that cause it, and immunity to one doesn’t protect you from others.

Is the stomach flu vaccine the same as the flu shot?

No, they’re completely different. The flu shot protects against influenza viruses that cause respiratory illness. There’s currently no vaccine for most viruses that cause stomach flu.

Conclusion

Viral gastroenteritis is never fun, but knowing how to manage it can make the experience more bearable. Remember that most cases resolve without medical treatment. Focus on rest, hydration, and gradual return to normal eating.

Prevention is always better than treatment. Practice good hygiene, especially during stomach flu season. If you do get sick, stay home to avoid spreading the infection to others.

With proper care and patience, you’ll be back to normal within a few days. Don’t hesitate to seek medical help if your symptoms are severe or you’re concerned about dehydration.

Was this article helpful?