How Long Does The Stomach Flu Last?

Most cases of stomach flu, also called viral gastroenteritis, last between 24 and 72 hours. The worst symptoms, which include vomiting, diarrhea, and stomach cramps, usually peak in the first 24 to 48 hours. After that, your body begins to recover, though loose stools and fatigue can linger for several days, especially in adults.

What Actually Causes the Stomach Flu?

Despite the name, the stomach flu has nothing to do with influenza. The flu is a respiratory illness. Stomach flu is an infection of the intestines caused by a virus.

The most common culprits are norovirus and rotavirus. Norovirus is responsible for most cases in adults. Rotavirus is more common in infants and young children. Other viruses, like adenovirus and astrovirus, can also cause it, though less frequently.

These viruses attack the lining of your small intestine. They cause inflammation and prevent your gut from absorbing water properly. That is why diarrhea is such a central symptom. Your body also triggers vomiting as a defense mechanism to expel the virus.

What Are the First Signs and Symptoms?

Symptoms usually appear 12 to 48 hours after exposure to the virus. The onset is often sudden. You may feel fine one moment and miserable the next.

Common symptoms include:

• Watery diarrhea
• Vomiting
• Nausea
• Stomach cramps
• Low-grade fever
• Muscle aches
• Headache

Not everyone gets every symptom. Some people only have diarrhea. Others vomit without diarrhea. Children tend to vomit more than adults. Fever is more common in children as well.

How Long Does the Stomach Flu Last in Adults?

For most healthy adults, the illness resolves within two to three days. The acute phase, where you are vomiting or having frequent diarrhea, typically lasts 24 to 48 hours.

Recovery is not always instant. Your intestines need time to heal. Loose stools may continue for up to a week after the virus is gone. This happens because the digestive enzymes and gut bacteria need to repopulate and restore normal function.

Fatigue is also common for several days after the worst symptoms pass. Your body spent significant energy fighting the infection. It is normal to feel weak or tired for a few more days.

How Long Does the Stomach Flu Last in Children?

Children follow a similar timeline, but there are differences. Kids often recover faster than adults. Many children feel better within 24 to 72 hours.

However, children are at higher risk for dehydration. Their smaller bodies lose fluids faster. Watch for signs like dry mouth, no tears when crying, decreased urination, and unusual drowsiness. These require prompt medical attention.

Rotavirus can cause more severe diarrhea in young children than norovirus. The diarrhea may last longer, sometimes up to eight days. If your child is under six months old and develops vomiting or diarrhea, contact your pediatrician early rather than waiting it out.

How Long Are You Contagious?

You are contagious while you have symptoms. You remain contagious for up to 48 hours after symptoms stop. Some people, especially those with norovirus, can shed the virus for two weeks or more after recovery.

This is why stomach flu spreads so easily. People return to work or school as soon as they feel better, not realizing they can still infect others.

The virus lives in stool and vomit. It spreads through contaminated hands, surfaces, food, and water. Hand sanitizer does not kill norovirus effectively. Washing hands with soap and water is the only reliable method.

What Is the Best Way to Treat the Stomach Flu?

There is no medication that cures viral gastroenteritis. Antibiotics do not work because the cause is a virus, not bacteria. The illness must run its course.

The only real treatment is supportive care. The main goal is preventing dehydration. Sip clear fluids frequently. Water, broth, and oral rehydration solutions are good choices. Oral rehydration solutions contain the right balance of salt and sugar to help your gut absorb fluids.

For adults, sports drinks can work in a pinch, but they contain too much sugar and not enough salt for ideal rehydration. Pediatric oral rehydration solutions are the standard for children.

Once vomiting subsides, return to a bland diet. The BRAT diet — bananas, rice, applesauce, and toast — is a traditional recommendation. It is gentle on the stomach. You can also eat plain crackers, boiled potatoes, and clear soups.

Rest is important. Your immune system is working hard. Pushing yourself too soon can prolong recovery.

When Should You See a Doctor?

Most cases do not require medical care. But some situations warrant a call to your doctor.

Seek medical attention if you experience any of these:

• Signs of severe dehydration
• Blood in your vomit or stool
• High fever above 102°F in adults
• Severe abdominal pain that does not come and go
• Vomiting that lasts more than 48 hours
• Inability to keep down any fluids for 24 hours

For infants and young children, dehydration is the biggest concern. Call your pediatrician if your child has not urinated in six hours, has a dry mouth, or is unusually sleepy and difficult to wake.

Older adults and people with weakened immune systems should also check in with a doctor earlier. Their bodies handle fluid loss differently and complications are more common.

Can You Prevent the Stomach Flu?

Good hygiene is the best defense. Wash your hands thoroughly with soap and water, especially after using the bathroom and before preparing food. Scrub for at least 20 seconds.

Clean contaminated surfaces with a bleach-based cleaner. Norovirus is resistant to many common disinfectants. Diluted bleach is one of the few things that reliably kills it.

Do not prepare food for others while you are sick. Wait at least two days after symptoms stop before cooking for anyone else. Wash fruits and vegetables thoroughly. Cook shellfish completely.

There is a vaccine for rotavirus. It is given to infants as part of the routine childhood immunization schedule. No vaccine exists for norovirus, though research is ongoing.

Why Do Some People Get It Worse Than Others?

Symptom severity varies widely. Your immune system, age, and overall health all play a role.

Young children, older adults, and people with chronic conditions like diabetes or kidney disease are more likely to have severe symptoms. Pregnant women also need to be careful because dehydration can affect the baby.

Genetics may also matter. Some people have a genetic resistance to norovirus. A small percentage of the population carries a gene that makes them less susceptible to infection. This is not something you can control, but it explains why one family member gets sick while another does not.

Frequently Asked Questions