Overview

Norovirus infection can cause the sudden onset of severe vomiting and diarrhea. The virus is highly contagious and commonly spread through food or water that is contaminated during preparation or through contaminated surfaces. You can also be infected through close contact with an infected person.

Diarrhea, stomach pain and vomiting typically begin 12 to 48 hours after exposure. Norovirus symptoms usually last one to three days, and most people recover completely without treatment. However, for some people — especially infants, older adults and people with underlying disease — vomiting and diarrhea can be severely dehydrating and require medical attention.

Norovirus infection occurs most frequently in closed and crowded environments such as hospitals, nursing homes, child care centers, schools and cruise ships.

Symptoms

Signs and symptoms of norovirus infection include:

  • Nausea
  • Vomiting
  • Stomach pain or cramps
  • Watery or loose diarrhea
  • Feeling ill
  • Low-grade fever
  • Muscle pain

Signs and symptoms usually begin 12 to 48 hours after exposure to norovirus and last one to three days. You can continue to shed virus in your feces for up to two weeks after recovery. This shedding can last weeks to months if you have an underlying health condition.

Some people with norovirus infection show no signs or symptoms. However, they are still contagious and can spread the virus to others.

When to see a doctor

Seek medical attention if you develop diarrhea that doesn't go away within several days. Also, call your doctor if you have severe vomiting, bloody stools, stomach pain or dehydration.

Causes

Noroviruses are highly contagious and are shed in the feces of infected humans and animals. You can get norovirus by:

  • Eating contaminated food
  • Drinking contaminated water
  • Touching your hand to your mouth after your hand has been in contact with a contaminated surface or object
  • Being in close contact with a person who has a norovirus infection

Noroviruses are difficult to kill off because they can withstand hot and cold temperatures and most disinfectants.

Risk factors

Risk factors for becoming infected with norovirus include:

  • Eating in a place where food is handled improperly
  • Attending preschool or a child care center
  • Living in close quarters, such as in nursing homes
  • Staying in hotels, resorts, cruise ships or other destinations with many people in close quarters
  • Having contact with someone who has norovirus infection

Complications

For most people, norovirus infection usually clears up within a few days and isn't life-threatening. But in some people — especially children, older adults and people with compromised immune systems — norovirus infection can cause dehydration. Norovirus infection can cause severe dehydration, malnutrition and even death, especially in people who are older or immunocompromised, or in women who are pregnant.

Warning signs of dehydration include:

  • Fatigue
  • Dry mouth and throat
  • Listlessness
  • Dizziness
  • Decreased urine output

Children who are dehydrated might cry with few or no tears. They might be unusually sleepy or fussy.

Prevention

Norovirus infection is highly contagious, and anyone can become infected more than once. To help prevent its spread:

  • Wash your hands thoroughly with soap and water, especially after using the toilet or changing a diaper.
  • Avoid contaminated food and water, including food that could have been prepared by someone who was sick.
  • Wash fruits and vegetables before eating.
  • Cook seafood thoroughly.
  • Dispose of vomit and fecal matter carefully to avoid spreading norovirus by air. Soak up material with disposable towels, disturbing it as little as possible, and place it in plastic disposable bags.
  • Disinfect surfaces that might have been contaminated. Use a chlorine bleach solution and wear gloves.
  • Stay home from work, especially if your job involves handling food. You might be contagious for as long as three days after your symptoms end. Children should stay home from school or child care.
  • Avoid traveling until your signs and symptoms are gone.