If it feels like everyone around you has had a “stomach bug” lately, you’re not imagining it. Viral gastroenteritis—commonly called the stomach flu—tends to circulate widely in communities, especially during the colder months. While it can feel miserable, most people recover within a few days with supportive care.

Here’s what you need to know about symptoms, how it spreads, and how to manage it safely at home.

What Is the Stomach Flu?

Stomach flu is an infection of the stomach and intestines caused by a virus. Despite the name, it is not related to influenza, which is a respiratory illness.

Common symptoms include:

• Nausea
• Vomiting
• Watery diarrhea
• Stomach cramps
• Low-grade fever
• Body aches
• Fatigue

For most healthy adults, symptoms last 1 to 3 days, though some people—especially young children, older adults, and those with weakened immune systems—may experience symptoms for 4 to 6 days.

What Causes the Stomach Flu?

Several viruses can cause gastroenteritis. The most common include:

Norovirus

Norovirus is the most common cause of viral gastroenteritis in Canada, responsible for roughly half of cases across all age groups. It spreads very easily and is especially common during winter months.

Rotavirus

Rotavirus is the leading cause of severe diarrhea in infants and young children. Symptoms can include vomiting, fever, abdominal pain, and watery diarrhea lasting 3 to 8 days. Widespread vaccination has significantly reduced rotavirus infections in many countries.

Adenovirus and Sapovirus

These viruses are less common but can cause similar symptoms of vomiting and diarrhea.

How the Stomach Flu Spreads

Viruses that cause gastroenteritis spread easily from person to person. Infection can occur through:

• Direct contact with someone who is infected
• Eating contaminated food or drinking contaminated water
• Touching contaminated surfaces and then touching your mouth
• Tiny droplets released during vomiting

Norovirus is particularly contagious. It takes very few viral particles (as few as 18) to cause infection.

When Are You Contagious?

One of the challenges with stomach viruses is that people can spread them even when they don’t feel very sick—or before symptoms begin.

Norovirus

• Most contagious while symptoms are present
• Still contagious for 48–72 hours after symptoms resolve
• Virus can continue to be shed in stool for about 4 weeks
• Up to 30% of infections may have no symptoms, but can still spread the virus

Rotavirus

• Incubation period is about 2 days
• Children can spread the virus before symptoms begin and for several days after recovery

Key takeaway: You can spread the virus before you feel sick, while you are sick, and for several days after you feel better.

How Long Do These Viruses Survive on Surfaces?

Viruses that cause gastroenteritis are very resilient in the environment.

• Norovirus can survive on surfaces for up to 2 weeks, and in some conditions 3–4 weeks.
• Rotavirus can survive hours on hands and days to months on hard surfaces.

These viruses tend to survive longer in cool, dry environments, which is one reason outbreaks often occur during winter.

How to Reduce the Spread

If someone in your household has the stomach flu, taking precautions can help reduce transmission.

1. Wash hands thoroughly

• Use soap and water, especially after using the bathroom, changing diapers, and before preparing food.
• Alcohol-based sanitizers are less effective against norovirus.

2. Stay home when sick

• Avoid work, school, and food preparation until at least 48 hours after symptoms stop.
• Some public health guidance recommends waiting up to 3 days before preparing food or caring for others.

3. Clean contaminated surfaces

• Disinfect areas that may have been exposed to vomit or stool.
• Keep others away from contaminated areas while cleaning.
• Clean surfaces frequently, especially during and in the 2 weeks following illness, and especially in households with young children. Kids often touch their bottoms during diaper changes or after using the bathroom and may not wash their hands thoroughly, which can transfer viruses from stool onto toys, doorknobs, bathroom surfaces, and other commonly touched areas.

4. Handle food carefully

• Wash fruits and vegetables thoroughly.
• Cook foods—especially shellfish—completely.

5. Wash contaminated clothing

• Launder soiled bedding, towels, and clothing promptly.

Treatment: What Helps

There is no medication that cures viral gastroenteritis. Treatment focuses on preventing dehydration and supporting recovery.

For Adults

• Drink fluids regularly: water, broth, or oral rehydration solutions
• Eat small, bland meals as tolerated
• Avoid alcohol, caffeine, and very sugary drinks, which can worsen symptoms

For Children

• Offer oral rehydration solutions such as Pedialyte in small, frequent sips
• Continue breastfeeding if applicable
• Resume the child’s normal diet as tolerated

Some pediatric guidelines recommend zinc supplementation during diarrheal illness to reduce duration and severity, though this should be discussed with a healthcare provider.

When to Seek Medical Care

Contact a healthcare provider if you or your child experience:

• Signs of dehydration (very little urine, dry mouth, dizziness, unusual sleepiness, or crying without tears)
• Blood in stool or vomit
• Fever lasting more than a few days
• Symptoms not improving after 3–5 days
• Infants under 3 months with vomiting or diarrhea
• Inability to keep fluids down

Importantly, antibiotics do not work against viruses and are not recommended for viral gastroenteritis.

Bottom Line

Stomach flu is common and very contagious, but most cases resolve on their own within a few days. The most important steps are:

• Stay well hydrated
• Rest and eat as tolerated
• Practice careful handwashing
• Avoid spreading the virus by staying home until symptoms have been gone for at least 48 hours
• Clean surfaces frequently, especially during and in the 2 weeks following illness

With supportive care and good hygiene practices, most people recover fully without complications.

Disclaimer: The information in this article is for informational purposes only and is not medical advice. Always consult your doctor before making any changes to your health, diet, or lifestyle.

Sources

• Public Health Agency of Canada – Norovirus and viral gastroenteritis guidance
• Health Canada – Food safety and illness prevention recommendations
• Centers for Disease Control and Prevention – Norovirus and rotavirus clinical information
• World Health Organization – Diarrheal disease management guidelines
• Hall AJ et al. Norovirus disease in the United States. Emerging Infectious Diseases.
• Lopman BA et al. Environmental transmission of norovirus gastroenteritis. Current Opinion in Virology.