Norovirus infection can cause severe vomiting and diarrhea that start suddenly. Noroviruses are highly contagious. They commonly spread through food or water that is contaminated during preparation or through contaminated surfaces. Noroviruses can also spread through close contact with a person who has norovirus infection.

Diarrhea, stomach pain and vomiting typically begin 12 to 48 hours after exposure. Norovirus infection symptoms usually last 1 to 3 days. Most people recover completely without treatment. However, for some people — especially young children, older adults and people with other medical conditions — vomiting and diarrhea can be severely dehydrating and require medical attention.

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

Signs and symptoms of norovirus infection may start suddenly and 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 your first exposure to a norovirus and last 1 to 3 days. You can continue to shed virus in your stool for several weeks after recovery. This shedding can last weeks to months if you have another medical condition.

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

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

Noroviruses are highly contagious. That means the norovirus infection can easily spread to others. The virus is shed in stool and vomit. You can spread the virus from the time you first have symptoms of illness until several days after you recover. Noroviruses can stay on surfaces and objects for days or weeks.

You can get norovirus infection 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 norovirus infection

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

Risk factors for becoming infected with a norovirus include:

• Eating in a place where food has been handled by someone with norovirus infection or the food has been in contact with contaminated water or surfaces
• 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 young children; older adults; and people with weakened immune systems or other medical conditions or who are pregnant — norovirus infection can be severe. Norovirus infection can cause severe dehydration and even death.

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. There are many types of noroviruses. Anyone can get norovirus infection more than once.

To prevent norovirus infection:

• Wash your hands thoroughly with soap and water for at least 20 seconds, especially after using the toilet or changing a diaper and before you prepare food and eat or drink. Alcohol-based hand sanitizers aren't as effective against noroviruses as using soap and water.
• 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.
• Disinfect surfaces that might have been contaminated. Wear gloves and use a chlorine bleach solution or a disinfectant that is effective against noroviruses.
• Use caution when traveling. If you're traveling to areas with a high risk of norovirus infection, consider eating only cooked foods, drinking only hot or carbonated beverages, and avoiding food sold by street vendors.

To help prevent norovirus infection spread, during illness and for 2 to 3 days after your symptoms end:

• Avoid contact with others as much as possible.
• Wash your hands thoroughly with soap and water.
• Stay home from work. Children should stay home from school or child care.
• Avoid handling food and items to be used by other people. Disinfect contaminated surfaces with a disinfectant effective against noroviruses.
• Dispose of vomit and stool carefully. Wearing disposable gloves, soak up material with disposable towels. Disturb soiled material as little as possible to avoid spreading noroviruses by air. Place soiled items in plastic bags and place them in the trash. Remove and wash clothes and linens that may be contaminated.
• Avoid traveling until 2 to 3 days after your symptoms are gone.

Norovirus infection is usually diagnosed based on your symptoms, but noroviruses can be identified from a stool sample. If you have a weakened immune system or have other medical conditions, your health care provider might recommend a stool test to confirm the presence of norovirus.

There's no specific treatment for norovirus infection. 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 not able to drink enough fluids to prevent dehydration, you might need to receive fluids through a vein (intravenous).

Your health care provider might recommend over-the-counter anti-diarrheal medication and medication to reduce nausea.

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 some fruit juices, can worsen diarrhea. Avoid beverages with caffeine and alcohol.

Ease back into eating. Try to eat small amounts of food frequently if you experience nausea. Otherwise, gradually begin to eat bland, easy-to-digest foods, such as soda crackers, toast, gelatin, bananas, applesauce, rice and chicken. Stop eating if your nausea returns. Avoid milk and dairy products, caffeine, alcohol, nicotine, and fatty or highly seasoned foods for a few days.

Remember that norovirus infection is highly contagious. Avoid contact with others as much as possible during illness and for several days after recovery. Wash your hands and disinfect surfaces and objects. Do not prepare food for others until your symptoms are gone.

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

What you can do

Before your appointment:

• 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, and their doses.
• Make a list of your key medical information, including other health conditions.
• Make a list of key personal information, including any recent changes or stressors in your life.
• Write down questions to ask your health care provider.

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 health care provider 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?

Your health care provider will ask additional questions based on your responses, symptoms and needs. Preparing and anticipating questions will help you make the most of your appointment time.