Norovirus Symptoms: Timeline, Treatment and When to Worry

The main symptoms of norovirus are sudden vomiting, watery diarrhea, nausea, and stomach pain or cramps. Some people also have a low fever, headache, and body aches. Symptoms start 12 to 48 hours after exposure and most people get better within 1 to 3 days, according to the Centers for Disease Control and Prevention (CDC). There is no specific medicine for it; the treatment is fluids, and the main danger is dehydration, especially in young children, older adults, and people with other illnesses.

This guide covers what norovirus feels like and how it unfolds, how to tell it from food poisoning and flu, when to call a doctor or 911, how to care for yourself and keep it from spreading, and what the latest U.S. data show. Linked pages go deeper on each topic.

Norovirus symptoms: the full list

Symptom	How common	What it is like
Nausea	Most common group (CDC)	Comes on abruptly, often the first sign
Vomiting	Most common group; affects more than half of patients in a typical outbreak	Sudden and forceful; usually worst in the first 24 hours; especially prominent in children
Watery diarrhea	Most common group	Frequent, loose, and watery, without blood
Stomach pain or cramps	Most common group	Comes in waves, often just before vomiting or a bowel movement
Fever	Other symptom	Usually low-grade; chills are possible
Headache	Other symptom	Often worse with dehydration
Body aches, tiredness	Other symptom	General weakness that can outlast the stomach symptoms by a few days

The CDC notes that a person with norovirus can feel extremely ill and vomit or have diarrhea many times a day. That intensity, arriving within hours in someone who felt fine at breakfast, is the signature of this virus.

First signs of norovirus

The earliest symptoms are usually a sudden wave of nausea, a queasy or "off" stomach, and cramping, followed quickly by vomiting or diarrhea. Some people notice chills, a mild headache, or unusual tiredness an hour or two beforehand. There is rarely a slow build over days; if your illness crept in gradually, something else is more likely.

Can you have norovirus without vomiting? Without diarrhea?

Yes to both. Not everyone gets every symptom. Adults are somewhat more likely to have diarrhea as the main problem, and children to have vomiting, but any combination occurs, including diarrhea alone or vomiting alone. Some people are infected and never feel sick at all: CDC outbreak guidance says up to 30 percent of norovirus infections cause no symptoms. A mild case still spreads the virus.

Does norovirus cause fever?

Sometimes, and usually a low one. A temperature above 102°F, or a fever that lasts more than a day or two, is not typical of norovirus and is a reason to call a doctor, because it raises the chance of a bacterial infection.

What norovirus stool looks like

Norovirus diarrhea is watery and loose and does not contain blood or pus. Color varies with what you have eaten and is not a reliable guide. Blood in the stool, or black, tarry stool, is not a norovirus symptom and needs medical attention.

Symptoms that are not norovirus

• Bloody diarrhea
• High or prolonged fever
• Cough, sore throat, or runny nose (think flu, COVID-19, or a cold)
• A rash
• Severe pain fixed in one spot, especially the lower right abdomen
• Illness that begins within a few hours of a meal (more typical of a bacterial toxin)
• Diarrhea lasting more than several days

Our comparison page, norovirus vs. food poisoning, stomach flu, and flu, explains how to tell these apart.

What is norovirus?

Norovirus is a very contagious virus that causes acute gastroenteritis, an inflammation of the stomach and intestines. People call it the stomach flu, the stomach bug, or the winter vomiting bug. It is not related to influenza, and the flu shot does not protect against it. It was formerly called Norwalk virus, after Norwalk, Ohio: the first norovirus was identified as the cause of a 1968 gastroenteritis outbreak there, at an elementary school, and researchers at the National Institutes of Health first saw the virus particle in 1972 in a stool sample from that outbreak.

It is the leading cause of vomiting and diarrhea from acute gastroenteritis in the United States, and the leading cause of foodborne illness. CDC estimates for a typical year:

Each year in the United States	Estimate
Illnesses	19 to 21 million
Outpatient visits	2.27 million
Emergency department visits	465,000, mostly young children
Hospitalizations	109,000
Deaths	About 900, mostly adults 65 and older
Reported outbreaks	About 2,500

Put another way, roughly 1 in every 16 or 17 Americans gets norovirus in a given year, and the great majority recover at home without seeing a doctor.

Norovirus timeline: from exposure to recovery

When	What happens
Hour 0	You swallow the virus from contaminated hands, food, water, or a surface
12 to 48 hours later	Symptoms begin, suddenly. The median in pooled studies is about 1.2 days.
First 24 hours of illness	The worst phase: repeated vomiting, watery diarrhea, cramps
Day 2 to 3	Vomiting stops; diarrhea tapers; appetite starts to return
48 hours after the last symptom	Earliest point to return to work, school, daycare, or cooking for others
2 weeks or more after recovery	Virus can still be shed in stool; keep washing hands carefully

Young children, older adults, and hospitalized patients can be sick for 4 to 6 days. For the hour-by-hour picture, including the incubation period and what counts as too long, see how long norovirus lasts.

Norovirus symptoms in adults, kids, and older adults

Adults

Healthy adults typically have one very rough day and one or two improving ones. Diarrhea, cramps, and exhaustion are often the dominant complaints. Most need only fluids and rest. Adults with diabetes, kidney or heart disease, or a weakened immune system, and those on diuretics or certain blood pressure medicines, dehydrate more easily and should contact their doctor early.

Babies and children

Vomiting is often the first and most striking symptom in children. Because of their small size, babies and toddlers can become dehydrated within hours. Watch diapers and tears: no wet diaper for 3 hours or more, crying without tears, a dry mouth, or unusual sleepiness or fussiness are warning signs. Any baby under 6 months with vomiting or diarrhea, and any baby under 3 months with a temperature of 100.4°F or higher, should be evaluated by a doctor. Amounts of fluid by age and the full list of red flags are in norovirus in babies and kids.

Adults 65 and older

Older adults account for most norovirus deaths. Symptoms can last longer, and thirst is a less reliable signal with age, so dehydration can develop quietly. Watch for dizziness, new confusion, weakness, falls, a fast heartbeat, or very little urine. In nursing homes and assisted living, where more than half of U.S. norovirus outbreaks occur, staff should be told about symptoms immediately.

Pregnancy

Symptoms are the same, and norovirus is not known to harm the baby directly, but dehydration and fever matter more. Federal guidance is for pregnant women with symptoms of viral gastroenteritis to contact a doctor right away. Safe medicines and warning signs are in stomach bug and norovirus during pregnancy.

Dehydration: the complication to watch for

Adults	Babies and young children
Extreme thirst, dry mouth and throat	Dry mouth and tongue
Urinating less than usual; dark urine	No wet diaper for 3 hours or more
Dizziness or light-headedness when standing	Crying with few or no tears
Tiredness	Unusual sleepiness or fussiness
Sunken eyes or cheeks	Sunken eyes; sunken soft spot on the head

Lists are drawn from the CDC, the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), MedlinePlus, and the American Academy of Pediatrics.

When to see a doctor, and when to call 911

Call a doctor or go to urgent care if an adult has:

• Diarrhea lasting more than 2 days
• Frequent vomiting, or cannot keep liquids down
• Six or more loose stools in a day
• A fever above 102°F
• Severe pain in the abdomen or rectum
• Stools that are black and tarry or contain blood or pus
• Signs of dehydration

Call the pediatrician right away if a child has:

• Diarrhea lasting more than a day
• Any fever in an infant, or a high fever in an older child
• Frequent vomiting or frequent loose stools
• Signs of dehydration
• Blood or pus in the stool, or black, tarry stool
• Severe belly pain
• A change in alertness, such as unusual irritability or lack of energy

Older adults, pregnant women, and people with a weakened immune system or another health condition should see a doctor right away if they have any symptoms of viral gastroenteritis, the NIDDK advises.

Call 911 or go to an emergency room for confusion, fainting, a seizure, a person who is hard to wake or too weak to stand, no urination, a rapid heartbeat or rapid breathing, trouble breathing, or a child who is limp or unresponsive. Severe dehydration is a medical emergency.

How do you know if it is norovirus?

Usually by the pattern: abrupt vomiting and watery diarrhea, a known exposure one or two days earlier, and recovery within three days. Most people are never tested, because the result would not change treatment.

When testing is needed, for severe or prolonged illness, for people at high risk, or during an outbreak, it is done on a stool sample in a laboratory. The CDC says diagnostic tests are available at all public health laboratories and many clinical laboratories. Its preferred method is RT-qPCR, which detects the virus's genetic material; commercial multiplex panels that check for norovirus and other gut infections at once have sensitivity in the same range. Rapid antigen tests (enzyme immunoassays) have poor sensitivity, 50 to 75 percent according to the CDC, and are generally not recommended for testing a single sample from an individual case.

How norovirus spreads and how long you are contagious

You get norovirus by getting tiny particles of an infected person's stool or vomit into your mouth: through direct contact, contaminated food or water, or contaminated surfaces. A sick person sheds billions of particles, and it takes only a few to infect someone else.

You are most contagious while you have symptoms and for the first few days after you feel better. The CDC advises staying home, and not preparing food or caring for others, for at least 48 hours after symptoms stop, and notes that you can still spread the virus for two weeks or more. You can get norovirus more than once, because there are many types and immunity to one may not protect against others. Details, including whether it is airborne and whether pets can catch it, are in how long norovirus is contagious.

Treatment at home

There is no specific medicine for norovirus, and antibiotics do not help. What works:

1. Fluids, in small frequent sips. Oral rehydration solutions sold over the counter are the most helpful for mild dehydration, the CDC says. Water, broth, and diluted juice or sports drinks also help most healthy adults.
2. Rest.
3. Food when you want it. You do not need a special diet; the BRAT diet is no longer recommended as a plan, though bland foods are fine to start with.
4. Caution with medicines. Adults can sometimes use loperamide or bismuth subsalicylate, but not with bloody diarrhea or fever, and these are not for young children.

What to drink, how much, what to eat, and a medicine-by-medicine table are in norovirus treatment.

Prevention: what works against norovirus

• Wash hands with soap and water for at least 20 seconds, especially after using the toilet or changing diapers and before eating or preparing food. Hand sanitizer does not work well against norovirus.
• Stay home when sick and for 48 hours after symptoms stop. Do not prepare food for others in that time.
• Disinfect with bleach. The CDC recommends 5 to 25 tablespoons of household bleach per gallon of water, left on for at least 5 minutes, or a product on the Environmental Protection Agency's List G.
• Wash soiled laundry with detergent and hot water on the longest cycle, and dry on high heat.
• Handle food safely. Rinse produce and cook oysters and other shellfish to at least 145°F.

Mixing amounts, a step-by-step cleanup, and which store products are actually registered against norovirus are in how to kill norovirus on surfaces, hands, and laundry.

Is norovirus going around? U.S. activity as of October 2026

Norovirus circulates year-round but is most common from November to April. As of our check on October 14, 2026:

• Current season: the CDC's NoroSTAT network of 12 states reported 27 outbreaks from August 1 to September 4, 2026, versus 29 in the same period a year earlier, within the normal range (data posted September 17, 2026).
• Last season (August 2025 to July 2026): 1,392 outbreaks in NoroSTAT states, an ordinary year.
• The season before (2024-25): 2,650 outbreaks, well above the usual range, driven by a strain called GII.17.
• Strains now: the long-established GII.4 Sydney strain is again the most common in CDC typing data updated October 9, 2026. No new strain has been reported.

Expect activity to rise through the holidays; searches for norovirus symptoms peaked in December last year. Updates, cruise ship outbreaks, oyster advisories, and ways to check your own area are in norovirus outbreaks in 2026.

Is there a norovirus vaccine?

Not yet. No norovirus vaccine is approved in the United States. The most advanced candidate, Moderna's mRNA-1403, is in a Phase 3 trial of more than 37,000 adults; the company reported on July 31, 2026 that an interim analysis did not meet the criteria for early success and that the blinded trial will continue through another winter. The full picture is in norovirus vaccine status.

Norovirus guide: all topics

Question	Where to read
Incubation period, duration, recovery	How long does norovirus last?
Contagious period, how it spreads, getting it twice	How long is norovirus contagious?
What to drink and eat, medicines, dehydration	Norovirus treatment
Bleach, hand sanitizer, EPA List G, laundry	How to kill norovirus
Food poisoning, stomach flu, flu, rotavirus	Norovirus vs. food poisoning
Infants, toddlers, and children	Norovirus in babies and kids
Pregnancy and breastfeeding	Norovirus during pregnancy
Current activity, cruise ships, oysters	Norovirus outbreaks 2026
Vaccine and antiviral research	Norovirus vaccine

This guide is general information and is not a substitute for care from your own doctor. If you are worried about how sick someone is, call.