Why Norovirus Matters, Explained Simply
Norovirus: what it is, why it matters, and what published guidance actually asks of you.
It is the leading cause of vomiting, diarrhea and foodborne illness in the US, and it spreads easily through food, surfaces and close contact.
Key takeaways
- Symptoms start: 12 to 48 hours after exposure
- Usual length: 1 to 3 days
- Most useful single change: Sip water, oral rehydration solution or broth often to replace lost fluids.
- Commonest mistake: Cooking or serving food for others while sick and for 2 days afterward.
- See a doctor if any of the signs under "When to speak to a doctor" below apply to you.
The short answer
A very contagious virus that causes sudden vomiting and diarrhea, often called the "stomach bug."
Where it fits
This is part of Infectious Diseases. The rest of this page works through the figures and then the practical side.
The numbers, in one place
| Measure | Figure |
|---|---|
| Symptoms start | 12 to 48 hours after exposure |
| Usual length | 1 to 3 days |
| Hand cleaning | soap and water for at least 20 seconds; hand sanitizer alone does not work well |
| Cleaning surfaces | a bleach solution or an EPA-registered disinfectant labeled for norovirus |
| Preparing food for others | wait at least 2 days after symptoms stop |
What that means in practice
What that looks like in practice:
- Sip water, oral rehydration solution or broth often to replace lost fluids
- Wash hands with soap and water after using the toilet, changing diapers and before eating or cooking
- Wear disposable gloves to clean up vomit or diarrhea, then disinfect the area
- Wash soiled laundry on the longest hot cycle and machine dry it
What gets people into trouble
And the things that tend to go wrong:
- Cooking or serving food for others while sick and for 2 days afterward
- Relying on alcohol-based hand sanitizer instead of hand washing
- Sending children back to child care or school before your provider or program says it is safe
Related topics
- The Evidence on Infection Prevention at Home, Without the Hype (Immunity)
- What the Guidance Really Says About Diarrhea (Digestive Health)
- Travelers' Diarrhea: What the Evidence Actually Says (Travel Health)
- Common Childhood Infections: What the Evidence Actually Says (Children's Health)
Where to go next
- Norovirus: Common Questions Answered
- Norovirus at a Glance
- Norovirus — the reference entry
- Infectious Diseases: The Complete Guide
- Strep Throat: What Published Guidance Supports
- Hepatitis A: Sorting the Evidence From the Noise
When to speak to a doctor
Call your doctor if vomiting or diarrhea lasts more than a few days, there is blood in the stool, or a baby, older adult or someone with a chronic condition cannot keep fluids down. Call 911 for signs of severe dehydration, such as very little or no urine, dizziness when standing, fainting, confusion, or a child who is unusually sleepy or fussy and cries without tears.
Where this comes from
- CDC — About Norovirus
- EPA — List G: EPA's Registered Antimicrobial Products Effective Against Norovirus
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarized or generalized beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to your doctor, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 911.
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