Basics
What is norovirus?
90-Second Answer
Last updated June 28, 2026
Short answer
Norovirus is a very contagious virus that can cause vomiting, diarrhea, nausea, and stomach pain.
What it means
CDC describes norovirus as a leading cause of vomiting and diarrhea from acute gastroenteritis. People sometimes call it the stomach flu, but norovirus is not influenza.
What to know
Norovirus can spread quickly in homes, schools, healthcare settings, restaurants, and cruise ships because only a small amount of virus can make someone sick.
When to check official guidance
Check CDC, state or local public health departments, or a healthcare professional for official guidance tied to a specific outbreak or illness.
Sources
Hantavirus Now summarizes external public health information in plain language. Source links open in a new tab.