Influenza is very common, especially in the fall and winter. You probably know the symptoms of the flu, such as cough and fever, but you may be wondering how long the flu will last.
In healthy children and adults, the flu usually lasts 3 to 7 days. However, if you develop complications, you will be unwell for longer. A cough from the flu can also last up to two weeks.
People with the flu are usually contagious the day before symptoms appear, and they can pass the flu to others for up to a week after symptoms appear. Children may spread the flu virus longer.
This article discusses everything you should know about the flu, including answers to frequently asked questions like “How long does the flu last in adults?” and “How Long Will Baby Flu Last?” It also covers treatment, prevention, and when to call a healthcare provider.
What is the flu?
Influenza, also known as the flu, is a common, highly contagious upper respiratory infection caused by a virus. The flu can strike at any time, but the virus spreads most widely during the cooler months. This means that your risk of getting the flu in the United States is highest between December and March.
Symptoms of the flu usually appear quickly. The most common symptoms are:
- Fever (although if you don’t have a fever, you can still get the flu)
- sore throat
- stuffy or runny nose
- muscle and body pain, headache
- tiredness and fatigue
Although some people associate the flu with gastrointestinal symptoms, these are not the main symptoms of the flu. Adults with flu occasionally experience vomiting and diarrhea, but these symptoms are most common in children and infants with flu.
When to call your doctor
Flu symptoms can range from mild to severe. You should see your healthcare provider or seek immediate medical attention if:
- Your symptoms persist for more than a week.
- You feel better, but then have a very or severe cough.
- Do you have any difficulty breathing.
- You have a fever of 105 degrees or higher that is not being treated with medication.
- You will feel chest pain.
- You feel dizzy or confused.
- You don’t urinate.
Usually, you can diagnose yourself with the flu. The flu comes quickly, with lots of body aches and fatigue. These symptoms can help you tell if you have the flu and not the common cold.
Health care providers can use laboratory tests to confirm a diagnosis of influenza. They will order your nose or throat swab and have the sample tested with a test, with results in as little as 15 minutes.
Unfortunately, rapid-result flu tests often give false negative results, meaning you have the flu, but the test came back negative. These tests are most accurate in infants, but their accuracy decreases with age.
More in-depth tests can identify which strain of flu virus you have, but these are for research purposes only.
How long is the flu contagious?
You can pass the flu to others about a day before symptoms start. Asymptomatic people — those who are not showing symptoms and don’t know they are infected — can also spread the flu.
Adults with the flu can spread the virus 5 to 7 days after they start showing symptoms, but are most contagious during the first 3 to 4 days after symptoms appear. Children and people with compromised immune systems can catch the flu for even more than a week.
If you want to know if you are still contagious, or if your child can return to school or day care, talk to your healthcare provider, school, and child care provider.
How long will the flu last?
The flu usually lasts three to seven days without treatment. Using antiviral therapy on the first day of infection can shorten the duration. Unfortunately, even in generally healthy people, coughing and discomfort (generally feeling sick) can persist for two weeks or more.
The biggest risk from the flu is complications. Complications are especially common in:
- Adults over 65
- pregnant woman
- People with underlying medical conditions such as asthma, diabetes and heart disease
Common complications of the flu are:
- Respiratory disorders, including croup (inflammation of the throat in children leading to barking), pneumonia (inflammation of the tiny air sacs in the lungs), and bronchiolitis (inflammation of the smallest airways in the lungs)
- Dehydration (loss of body fluids without adequate replacement)
Rare and more serious complications may include:
- Heart disease, including myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the sac around the heart)
- Nervous system disease
- Complications of underlying health conditions, including diabetes and lung disease
- organ failure and death
If you are at high risk for complications, you should contact your healthcare provider if you think you have the flu.
Taking antiviral medication within the first one to two days of symptoms can help treat the flu. These drugs are recommended for people at high risk of complications to reduce the severity of the flu. The four antiviral drugs used to treat the flu are:
- Lapivalbub (Peramivir)
- Reloza (zanamivir)
- Tamiflu (oseltamivir phosphate)
- Xofluza (baloxavir marboxil)
All of these medicines need to be started as soon as symptoms appear, so contact your doctor if you suspect you have the flu.
The most effective way to prevent getting the flu or severe flu is to get the flu vaccine. The Centers for Disease Control and Prevention (CDC) recommends that almost everyone 6 months and older get an annual flu shot.
Common hygiene and safety measures—such as frequent hand washing and covering coughs and sneezes—can also prevent the spread of the flu. In 2020, influenza transmission rates were at an all-time low, likely due to COVID-19 precautions also preventing influenza transmission. It is unclear how the pandemic will affect influenza rates in future flu seasons.
For most healthy people, the flu goes away on its own within three to seven days. However, if you are over 65 or have an underlying medical condition, please contact your healthcare provider as soon as you develop symptoms. Your healthcare provider may recommend prescription antiviral medications that can shorten or reduce the severity of the flu.
For most people, the flu goes away on its own. Unfortunately, you may have a cough or generally feel sick for two weeks after getting the flu. If you think you or your child has the flu, contact your healthcare provider, who may offer treatment options.
Frequently Asked Questions
What are the stages of the flu virus?
The flu phase begins the day before you develop symptoms, when you are contagious. On the first to third days, you will feel fever, pain, and tiredness. Usually, symptoms begin to improve by the fourth day.
By day seven, you may be back to your normal activities, although you may not feel quite like yourself for two weeks.
What medicine can I take for a cold?
There are four prescription antiviral drugs approved to treat the flu. Ask your doctor which is right for you.
Adults can manage flu symptoms with over-the-counter medications such as pain relievers and cough suppressants. If your child has the flu, talk to your healthcare provider about symptom control.