is the flu contagious
Last updated September 6, 2026.
Yes, the flu is contagious, and most people can spread it starting about one day before symptoms appear through roughly 5 to 7 days after getting sick. Flu viruses spread mainly through droplets made when you cough, sneeze, or talk, and less often by touching a contaminated surface and then your mouth, nose, or eyes. Children and people with weakened immune systems can spread the virus longer than a week. Fever is a useful marker: CDC advises staying home until you have been fever-free for at least 24 hours without fever-reducing medicine. Annual vaccination, handwashing, and covering coughs cut the chance you pass it on. Antiviral treatment works best when started within 2 days of symptoms, so call a clinician early if you are at higher risk.
What to do
- Count from day one: Assume you were contagious the day before symptoms started and tell close contacts you saw then.
- Use the fever rule: Stay home until your temperature has been normal for a full 24 hours without acetaminophen or ibuprofen.
- Separate at home: Sleep in a different room if you can, open a window, and wear a mask around household members.
- Wash and cover: Clean your hands with soap and water often, and cough into a tissue or your elbow rather than your hand.
- Ask about antivirals early: Oseltamivir and similar drugs work best within 2 days of symptom onset, especially if you are at higher risk.
- Get vaccinated yearly: A flu shot each fall lowers your chance of catching flu and passing it to people who cannot fight it off easily.
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