What Are the Symptoms of Norovirus and How Long Do They Last?

• Norovirus, also known as the stomach flu, is a highly contagious virus that can cause nausea, vomiting, stomach cramps, and diarrhea.

• Experts say most people can recover from illness in about one to three days after symptoms begin, however, that can vary by person.

• There is no vaccine or medication to treat norovirus, but experts say the best way to protect yourself is to wash your hands frequently.

Norovirus, an extremely contagious stomach bug, is making its way across the United States and other parts of the world. It can lead to gastroenteritis (stomach flu), causing symptoms such as vomiting, nausea, stomach pain, and diarrhea.

As of February 28, the average positive rate of norovirus tests was around 17%, higher than last season’s peak at about 15% in March 2022, according to data from the Centers for Disease Control and Prevention (CDC). States including California, Michigan, and Virginia are particularly seeing cases of norovirus outbreaks.

Sara Mirza, PhD, MPH, an epidemiologist at CDC, said the norovirus cases this year are still within a normal range. “We typically see cases go up around this time of year across the country, so it’s not unusual to see that. This is really on track with what we normally expect for norovirus season,” she told Verywell.

She said norovirus cases may appear higher this season than the last because fewer people are following COVID-19 safety protocols.

“We weren’t seeing as many cases because people were washing their hands, they were at home, were less likely to go to restaurants and have big gatherings,” Mirza said. “With things opening back up and people out there again, we’re going back to what we used to see pre-pandemic, which was increased cases of norovirus during this time of year.”

Related:Food Poisoning vs. Stomach Flu: What Are the Differences?

How Does Norovirus Spread?

Norovirus is highly contagious. You can get norovirus from sharing food with or caring for an infected person, even if they have no symptoms. Or you can get it from eating food or drinking liquids that are contaminated with the virus.

Most norovirus outbreaks happen in food service settings, such as restaurants, school cafeterias, and cruise ships. Ready-to-eat foods, whether raw or cooked, can be contaminated if an infected worker touches them before serving.

Shanthi Kappagoda, MD, a board-certified infectious disease physician at Stanford Health Care, told Verywell in an email that oysters, fresh fruits, leafy greens, unpasteurized juice, and sometimes water are most commonly linked to norovirus outbreaks.

You can also get infected from touching contaminated surfaces like shopping carts and door handles. “Norovirus particles can remain viable on a surface such as a countertop for five to 12 days,” Kappagoda said.

How Long Does Norovirus Last?

Common norovirus symptoms include nausea, vomiting, stomach pain, diarrhea, body aches, headaches, and a low-grade fever. A person usually develops some of these symptoms 12 to 48 hours after being exposed to the virus.

Some people may not show any signs or symptoms, but they can still be contagious.

Typically, people are considered infectious about 24 hours after they’re first exposed and up to two weeks after they have recovered, Kappagoda said. However, they’re the most contagious in the first 48 hours after symptom onset.

Most people recover within one to three days, according to the CDC. Mirza said the illness could last longer in those who are immunocompromised or have other underlying health conditions.

What Should You Do If You Have Norovirus?

If you have a norovirus infection, drink plenty of fluids to replace the liquids that are lost from vomiting and diarrhea and to prevent dehydration. “Dehydration is something that we want to avoid because severe dehydration may require hospitalization for treatment with fluids,” Mirza said.

People should watch for signs of severe dehydration, including dry mouth, feeling thirsty, dark/concentrated urine, and dizziness. Small children who are dehydrated might cry frequently but have no tears.

If you suspect symptoms of severe dehydration, contact your healthcare provider, Mirza said.

Beyond staying hydrated, Kappagoda said the illness can generally be managed at home with rest and eating a bland diet, such as rice, boiled potatoes, crackers, bananas, and clear soups.

There are no antiviral drugs or antibiotics that are safe and effective for treating norovirus infection since these types of medications fight bacteria and not viruses. “Antibiotics are not helpful for norovirus and can themselves cause diarrhea,” Kappagoda said.

Related:A Guide to the BRAT Diet

Can You Test for Norovirus?

There are some PCR stool tests that can detect norovirus, but they must be performed by a healthcare provider, Kappagoda said. There are no at-home tests available.

If there’s an ongoing norovirus outbreak and a person develops typical symptoms of norovirus, healthcare providers tend to make a presumptive diagnosis rather than performing a test. That’s “because the testing is expensive and typically the patient will likely already be feeling better by the time the test results become available,” Kappagoda added.

How Can You Protect Yourself from Norovirus?

The best way to prevent a norovirus infection is to frequently wash your hands with soap and water, especially after using the bathroom, changing a child’s diaper, handling commonly-touched surfaces, and before eating or preparing food, Mirza said.

The CDC also recommends washing fruits and vegetables thoroughly and cooking raw seafood like oysters and shellfish all the way before consuming them. People should also avoid preparing or cooking meals for others when they’re sick and for at least two to three days after recovery.

You can also clean and disinfect contaminated surfaces with a chlorine bleach solution or other disinfectants that are registered as effective against norovirus by the Environmental Protection Agency (EPA) and wash contaminated clothes, blankets, and other linens to protect yourself and to prevent norovirus from spreading.

Read Next:How to Wash Your Hands

If you have norovirus, you may experience vomiting, diarrhea, and stomach pain, however, the illness typically lasts between one to three days. If you experience symptoms of severe dehydration, reach out to a healthcare provider.