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.

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.

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 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

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.

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.

Diagnosis is usually based on your symptoms, but norovirus can be identified from a stool sample. If you are immunocompromised or have other health problems, your doctor might recommend a stool test to confirm the presence of norovirus.

There's no specific treatment for norovirus infection, and recovery generally depends on the health of your immune system. In most people, the illness usually resolves within a few days.

It's important to replace lost fluids. Oral rehydration solutions may be used. If you're unable to drink enough fluids to prevent dehydration, you might need to receive fluids through a vein.

Your doctor also might recommend over-the-counter anti-diarrheal medication.

If your family includes young children, it's a good idea to have commercially prepared oral rehydration solutions on hand. Adults can drink sports drinks, broths or oral rehydration solutions. Drinking liquids that contain a lot of sugar, such as soft drinks and fruit juices, can worsen diarrhea.

Smaller meals and a bland diet might help limit vomiting. Some foods to consider:

• Soup
• Starches and cereals, such as potatoes, noodles, rice or crackers
• Bananas
• Yogurt
• Broiled vegetables

Here's some information to help you get ready for your appointment.

What you can do

• Write down your symptoms, including when the illness began and the frequency of the vomiting and diarrhea.
• Make a list of all your medications, vitamins or supplements.
• Write down your key medical information, including other conditions.
• Write down key personal information, including any recent changes or stressors in your life.
• Write down questions to ask your doctor.

Questions to ask your doctor

• What's the most likely cause of my symptoms?
• What treatments can help?
• How can I avoid spreading my illness to other people?

Don't hesitate to ask other questions.

What to expect from your doctor

Your doctor is likely to ask you a number of questions, including:

• How long have you or your child had symptoms?
• How frequent are the vomiting and diarrhea?
• Does the vomit or diarrhea contain mucus, blood or a dark green fluid?
• Have you or your child had a fever?