How long the flu lasts

• The whole thing: a few days to less than two weeks for most people (CDC).
• The fever: usually gone in three to four days, and it can last up to eight (MedlinePlus).
• Everything else: better in seven to fourteen days. The cough and the tired feeling can last for weeks (MedlinePlus).
• From exposure to symptoms: about two days, anywhere from one to four (CDC). The flu comes on fast, within hours (NHS), which is one way it differs from a cold.

No source gives a day-by-day arc, so this page does not either. If you are not improving after seven days, the NHS says to contact a doctor.

You are most contagious in the first three days of being sick. The CDC says some healthy adults may be able to infect others from a day before symptoms start to five to seven days after, and children and people with weakened immune systems can be contagious longer (CDC).

The CDC's rule for going back to normal life: for at least 24 hours, your symptoms are getting better overall and you have not had a fever, and are not using fever-reducing medicine. Until then, stay home except to get medical care.

• Rest, and drink plenty of fluids. The NHS test: your pee should be light yellow or clear.
• Acetaminophen or ibuprofen lowers the fever and eases the aches (MedlinePlus).
• No aspirin for anyone 18 or younger, and nothing with salicylates such as Pepto-Bismol. The CDC's reason is Reye's syndrome, a rare and very serious complication.

Antiviral medicine works best when it starts within two days of the first symptoms, and it shortens the illness by about a day (CDC, MedlinePlus). The CDC says people at higher risk of complications should get it as early as possible: adults 65 and older, children under two, anyone pregnant or within two weeks of a pregnancy, and people with asthma, lung disease, diabetes, heart disease, kidney or liver disease, a weakened immune system, or a body mass index of 40 or more. If that is you or someone you care for, the CDC's advice is to get treatment as early as possible, which means not waiting to see how the first days go.

The CDC is direct about this: you cannot reliably tell the flu from a cold or from COVID by symptoms alone, and only a test can. In general the flu is worse than a cold and starts more abruptly, and a runny or stuffy nose is more typical of a cold. If it matters for treatment, which it does for antivirals, get tested.

I never diagnose and I never tell you what to take. What I do is check on you every day: how the fever is, whether fluids are going in, whether you slept. I hold what you tell me against the CDC's warning signs and say so out loud if something on that list shows up. When you want to go back to work, I apply the 24-hour rule to your actual days.

No clinician reviewed this page. It restates the CDC, MedlinePlus, and NHS pages linked below, and those are the documents to trust over anything here.