Most people who get flu recover in a few days to less than two weeks, according to the Centers for Disease Control and Prevention. The agency says some people develop complications, such as pneumonia, that can be life-threatening. This page reports what the CDC states and is not personal medical advice.
The flu timeline
| Stage | What the CDC says |
|---|---|
| Exposure to first symptoms | About two days, with a range of one to four days |
| Fever | Common, lasts 3 to 4 days |
| Most contagious | The first three days of illness |
| Recovery for most people | A few days to less than two weeks |
The first and third rows come from the CDC's page on how flu spreads. The second and fourth rows come from its page on the signs and symptoms of flu, where the fever figure appears in a table that compares a cold with flu. That page also says flu symptoms usually come on suddenly and that not everyone with flu will have a fever.
What the symptoms are
The CDC says people who have flu often feel some or all of these signs and symptoms:
- Fever or feeling feverish, or chills
- Cough
- Sore throat
- Runny or stuffy nose
- Muscle or body aches
- Headaches
- Fatigue (tiredness)
- Vomiting and diarrhea in some people, which the agency says is more common in children than in adults
For the symptoms of norovirus, see What are the symptoms of norovirus?
How long a person with flu is contagious
The CDC says influenza viruses can be detected in most infected people beginning one day before symptoms develop and up to five to seven days after becoming sick. People with flu are most contagious during the first three days of their illness, according to the same page. The agency says some people, including young children and people with weakened immune systems, may be contagious for longer.
When the CDC says a person can return to normal activities
The CDC's guidance on preventing the spread of respiratory viruses says a sick person should stay home and away from others, and can go back to normal activities when both of these have been true for at least 24 hours:
- Symptoms are getting better overall.
- The person has not had a fever and is not using fever-reducing medication.
The same page says to take added precautions over the next 5 days after returning, such as steps for cleaner air, good hygiene, a well-fitted mask, physical distancing or testing. The reason the agency gives is that a person at that point is typically less contagious, but the body still needs more time to fully get rid of the virus. The page says a person who develops a fever or starts to feel worse after returning should stay home and away from others again.
Whether treatment shortens the flu
The CDC's page on flu treatment says flu antiviral drugs can lessen symptoms and shorten the time a person is sick by about a day. The agency says the drugs work best when started early, ideally within two days after flu symptoms begin.
When flu lasts longer or gets worse
The CDC lists sinus and ear infections as examples of moderate complications from flu and pneumonia as a serious one. The agency says flu can also make chronic medical problems worse, and gives asthma attacks in people with asthma as an example.
The same page gives emergency warning signs and says people who have them should get medical care right away. For adults, the signs it lists are:
- Difficulty breathing or shortness of breath
- Persistent pain or pressure in the chest or abdomen
- Persistent dizziness, confusion or inability to arouse
- Seizures
- Not urinating
- Severe muscle pain
- Severe weakness or unsteadiness
- Fever or cough that improve but then return or worsen
- Worsening of chronic medical conditions
The CDC gives a separate list for children, which includes fast breathing or trouble breathing, bluish lips or face, and any fever in a child younger than 12 weeks. The agency says its lists do not include every sign and that a medical provider should be consulted about any other symptom that is severe or concerning.
To see how much respiratory illness the CDC is reporting where you live, see Is flu and respiratory illness high in my state?