For most healthy adults, the flu lasts about seven days from the first symptom to feeling mostly recovered. The worst of it, including fever, body aches, and chills, typically peaks around day two and starts improving by day three or four. A lingering cough and fatigue can stick around for another week or two after that.
What the First Few Days Look Like
After you’re exposed to the flu virus, symptoms take one to four days to appear. When they do, they tend to hit fast. You might wake up feeling fine and be flattened by afternoon with chills, a headache, muscle pain, and a fever that can climb anywhere from 100.4°F to 104°F. Sore throat, a dry cough, and loss of appetite usually arrive at the same time.
Day two is typically the peak. Fever stays high, body aches feel intense, and congestion, coughing, and sore throat often worsen. Some people get headaches, dizziness, or sensitivity to light. By day three, most people start turning a corner. Fever begins to drop, and body aches ease up a bit, though fatigue and congestion hang on. Some people develop a deeper, wetter cough around this point as mucus production increases.
Days Four Through Seven: The Recovery Phase
By day four, the shift is noticeable. Your fever should be gone or nearly gone, though you’ll still feel drained and may have a sore throat or cough. Day five is when most people start feeling meaningfully better. You can get out of bed, move around, and may actually want to eat again. Your immune system is still rebuilding, so some fatigue, coughing, or mild sinus pressure is normal.
By the end of the first week, many people are mostly recovered. The acute illness is behind you, but don’t be surprised if you’re not quite at 100%.
Symptoms That Linger Into Week Two
It’s common to feel “off” for another week or so after the main illness clears. A post-viral cough is one of the most frequent holdovers, persisting for three to eight weeks in some cases as your respiratory system finishes healing. Fatigue can also drag on, making workouts harder and afternoons sluggish even when you otherwise feel fine. These lingering symptoms don’t mean you’re still sick with the flu. They’re aftereffects of the inflammation your body went through fighting it off.
How Long You’re Contagious
You can spread the flu to others starting about one day before your symptoms appear, which means you may be contagious before you even know you’re sick. The most contagious window is the first three days of illness, when viral levels are highest. Most healthy adults remain infectious for five to seven days after symptoms start.
Young children and people with weakened immune systems can shed the virus for longer, sometimes extending the contagious period beyond that seven-day mark.
When You Can Go Back to Work or School
The CDC’s current guidance says you can return to normal activities when both of these have been true for at least 24 hours: your symptoms are improving overall, and you haven’t had a fever without using fever-reducing medication. For most people, that lands somewhere around day five to seven.
Even after you return, the CDC recommends taking extra precautions for the next five days. That includes wearing a mask around others, improving ventilation, and keeping your distance when possible. If your fever comes back or symptoms get worse after you’ve resumed activities, stay home again until you meet those same criteria.
Can Antivirals Shorten It?
Prescription antiviral medications can reduce how long symptoms last, but the benefit is modest, typically about one day shorter. They work best when started within 48 hours of your first symptoms. One study found that even when treatment began at the 72-hour mark, it still shortened symptoms by roughly a day compared to no treatment. For influenza B specifically, one newer antiviral cut recovery time by more than 24 hours compared to older options.
The biggest value of antivirals is for people at high risk of complications, including adults over 65, young children, pregnant women, and those with chronic health conditions. For otherwise healthy adults, the flu is miserable but self-limiting, and most people recover on their own within a week.
Who Takes Longer to Recover
Older adults, people with weakened immune systems, and those with chronic conditions like asthma, diabetes, or heart disease often experience a longer and more difficult course. Their immune response may be slower to contain the virus, which extends both the duration of symptoms and the contagious period. Recovery can stretch well beyond the typical one-week timeline, and the risk of complications like pneumonia is significantly higher in these groups.
Children also tend to run fevers longer than adults and may be contagious for a more extended period. For young kids, it’s not unusual for the acute phase to last a full week before improvement begins.