You can spread the flu from about 1 day before symptoms start until 5 to 7 days after you get sick - and you are most contagious in the first 3 days.
That pre-symptom day is why flu tears through households: people spread it before they feel sick. Young children and people with weakened immune systems can shed virus for longer. Flu travels mainly through droplets from coughs, sneezes, and conversation, and through surfaces you touch and then your face. A sound return-to-work rule is 24 hours fever-free without fever-reducing medicine, plus extra care around high-risk people for a few more days. If you are unsure whether you have flu or a cold, Pymander is a free AI doctor, 24/7 by text, and can help you sort the difference.
What to do
Common questions
How long is the flu contagious?
You can spread the flu starting about one day before your symptoms appear and for roughly five to seven days after you get sick, according to the CDC. You are most contagious during the first three days of illness, when symptoms are at their peak. Young children and people with weakened immune systems can stay contagious longer. This window explains why flu moves through households and offices so fast: people shed virus before they even know they are sick. Flu spreads mostly through droplets from coughing, sneezing, and talking, plus contaminated surfaces. A practical rule for returning to work or school: stay home until you have been fever-free for at least 24 hours without fever-reducing medicine, and keep your distance from high-risk people a few days beyond that. Not sure whether it is flu or a bad cold? Pymander is a free AI doctor, 24/7 by text, that can help you tell them apart.