Norovirus: How It Spreads, How Long You're Contagious, and When You Need IV Fluids
Norovirus is the most common cause of the 'stomach flu.' Here's how it spreads, how long you're contagious, how to keep it from taking out the whole house, and when you need IV fluids.
Norovirus is the most common cause of the "stomach flu": sudden vomiting, watery diarrhea, nausea and stomach cramps, usually starting 12 to 48 hours after exposure and lasting one to three days. It spreads very easily, and you're most contagious while you're sick and for the first few days after, though the virus can stay in your stool for two weeks or more. The main risk is dehydration. If you can't keep fluids down, IV fluids can help fast.
Norovirus symptoms
- Sudden nausea and vomiting, often forceful
- Watery diarrhea
- Stomach cramps
- Sometimes a low fever, chills, headache and body aches
Symptoms usually hit fast, often in the middle of the night, and most people feel better within one to three days. Norovirus isn't related to the flu, despite the "stomach flu" name. Our post on the stomach bug covers other causes too, and our food poisoning post explains how that differs.
How norovirus spreads
It takes only a tiny amount of virus to make someone sick. It spreads through:
- Close contact with someone who is sick, especially caring for them
- Touching contaminated surfaces, then your mouth
- Food or water handled by someone who is sick
- Tiny particles in the air when someone vomits
Outbreaks are common from November through April, and in schools, daycares, nursing homes, cruise ships and restaurants.
How long are you contagious?
You're most contagious while you have symptoms and for the first three days after you feel better. The virus can stay in your stool for two weeks or more, so careful handwashing still matters after you've recovered. People who work with food, in childcare or in healthcare are usually asked to stay home until at least 48 hours after symptoms stop. Check with your workplace or school.
Keeping it from spreading at home
- Wash hands with soap and water for at least 20 seconds, especially after the bathroom and before eating. Hand sanitizer doesn't work well against norovirus.
- Clean with bleach: use a bleach solution (about 5 to 25 tablespoons of household bleach per gallon of water) or a cleaner labeled for norovirus on counters, toilets, faucets and door handles
- Don't prepare food for others while you're sick and for at least two days after
- Wash laundry that may be contaminated right away, on the longest hot cycle, and dry it on high heat
- Use a separate bathroom for the sick person if you can
What helps
- Small, frequent sips of water or an oral rehydration drink, even if you can only manage a spoonful every few minutes
- Popsicles or ice chips for children who won't drink
- Bland food once vomiting stops, such as crackers, toast, rice and bananas
- Rest
Antibiotics don't work on norovirus, because it's a virus. Avoid anti-diarrhea medicine for children unless a clinician recommends it.
Signs of dehydration
- Peeing much less than usual, or dark urine
- Dry mouth and throat
- Dizziness when standing up
- Unusual tiredness
- In children: crying with few or no tears, fewer wet diapers, or being unusually sleepy or fussy
When IV fluids help
If you can't keep fluids down, or you're showing signs of dehydration, a clinician can give IV fluids and anti-nausea medicine, and most people feel noticeably better before they leave. Older adults, young children, pregnant people and anyone with a chronic condition can get dehydrated faster, so get seen early. See our IV hydration page.
At an AfterOurs clinic, a standard self-pay visit is $175, and a self-pay in-clinic visit never costs more than $330. We contract with all major commercial and government plans, including Colorado Medicaid and Medicare. See our stomach bug page and the cost and insurance page.
Go to the ER or call 911 if there's blood in the vomit or stool, vomit that's green or looks like coffee grounds, severe or constant belly pain, a stiff neck, confusion, fainting, no urine for 8 hours or more, or a baby or young child who is very sleepy, floppy or hard to wake.
Where to find us
Four clinics across metro Denver, all ages welcome, se habla español:
- Hampden (Southeast Denver): 8 AM–11 PM daily
- Littleton: 8 AM–11 PM daily
- Thornton: 8 AM–11 PM daily
- Highlands: Mon–Fri 5–11 PM, Sat–Sun 8 AM–11 PM
Walk in, or book online.
Medically reviewed by Peter Martinuzzi, MD
This article is general health information, not medical advice for your situation. If you are worried, come in or book a telehealth visit — and if it is an emergency, call 911.