How Long Does the Flu Last?

Influenza is extremely common, especially during the fall and winter months. You probably know about symptoms of the flu, like coughing and fever, but might wonder how long the flu lasts.

In healthy children and adults, the flu typically lasts for three to seven days. However, if you develop complications, you'll feel sick much longer. The cough from the flu can also stick around for up to two weeks. 

People with the flu are often contagious a day before they experience symptoms, and they can pass the flu to others for up to a week after symptoms appear. Kids might spread the flu virus for even longer. 

This article discusses everything you should know about the flu, including answers to common questions like “How long does the flu last in adults?” and “How long does the flu last in babies?” It also covers treatment, prevention, and when to call a healthcare provider. 

What Is Influenza?

Influenza, known as the flu, is a very contagious and common upper respiratory infection caused by a virus. The flu can happen at any time, but the virus circulates most widely in the colder months. That means that your risk of contracting the flu in the United States is highest between December and March.

Symptoms

The symptoms of the flu usually come on quickly. The most common symptoms are:

• Fever (although you can still have the flu if you don’t have a fever)
• Chills
• Cough
• Sore throat
• Stuffy or runny nose
• Muscle and body aches, headaches 
• Tiredness and fatigue

Although some people associate the flu with gastrointestinal symptoms, these are not primary symptoms of influenza. Adults with the flu will occasionally experience vomiting and diarrhea, but those symptoms are most common in kids and babies with the 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 last more than a week.
• You feel better but then develop a very or severe cough.
• You have any trouble breathing.
• You have a fever of 105 degrees or higher that does not come down with medication.
• You experience chest pain.
• You feel dizzy or confused.
• You are not urinating.

Diagnosis 

Oftentimes you can diagnose yourself with the flu. Flu comes on quickly, with lots of body aches and fatigue. Those symptoms help you tell that you have the flu and not the common cold. 

Healthcare providers can confirm a diagnosis of flu using lab tests. They will order a swab of your nose or throat and run the sample through a test that gives results in just 15 minutes.

Unfortunately, rapid-result flu tests often give false-negative results, meaning you have influenza but the test reads negative. The tests are most accurate in babies and decrease in accuracy with age. 

More in-depth tests can identify the strain of flu that you have, but these are only used for research purposes.

How Long Is the Flu Contagious?

You can pass the flu on to others starting about a day before your symptoms start. Asymptomatic people—those who are not showing symptoms and don’t know they’re infected—can also spread the flu.

Adults with the flu can pass the virus for five to seven days after they begin experiencing symptoms, although they’re most contagious in the first three to four days after symptoms appear. Children and people with compromised immune systems may pass the flu for even longer than a week.

If you’re wondering whether you’re still contagious or if your child can return to school or day care, talk with your healthcare provider, school, and childcare provider. 

How Long Does the Flu Last?

The flu typically lasts for three to seven days without treatment. Using an antiviral treatment during the first day of infection can shorten the duration. Unfortunately, the cough and malaise (a general feeling of being unwell) can last two weeks or longer, even in people who are generally healthy.

Complications

The biggest risk from the flu is developing complications. Complications are particularly common in:

• Children
• Adults over age 65
• Pregnant people 
• People with underlying medical conditions including asthma, diabetes, and heart disease

Common complications from the flu are:

• Respiratory conditions, including croup (inflammation of the throat in children that leads to a barking cough), pneumonia (inflammation of the tiny air sacs in the lungs), and bronchiolitis (inflammation of the tiniest airways in the lungs)
• Dehydration (loss of body fluids without adequate replacement)

Rare and more serious complications can include:

• Cardiac conditions, including myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the sac surrounding the heart)
• Neurological conditions
• Complication of underlying health condition, including diabetes and lung disease
• Organ failure and death

If you are in a group that is at high risk for complications, you should contact your healthcare provider if you believe you have the flu.

Treatment

Antiviral drugs administered within the first one to two days of symptoms can help treat the flu. The drugs are recommended for people at high risk for complications, in order to make the flu less severe. The four types of antiviral drugs used to treat the flu are:

• Rapivab (peramivir)
• Relenza (zanamivir)
• Tamiflu (oseltamivir phosphate)
  
• Xofluza (baloxavir marboxil)

All of these medications need to be started soon after the onset of symptoms, so reach out to your doctor if you suspect you have the flu. 

Prevention

The most effective way to prevent infection with the flu or a serious case of the flu is to get a flu vaccine. The Centers for Disease Control and Prevention (CDC) recommends that nearly everyone ages 6 months and older get an annual influenza vaccine.

Common hygiene and safety measures—like frequently washing hands and covering coughs and sneezes—also prevent the spread of flu. In 2020, the spread of flu was historically low, likely due to COVID-19 precautions that also prevented the flu from spreading. It’s not yet clear how the pandemic will affect flu rates in future flu seasons.

Summary

For most healthy people, the flu will resolve on its own within three to seven days. However, if you’re over the age of 65 or have underlying health conditions, reach out to your healthcare provider as soon as symptoms begin. Your healthcare provider might recommend prescription antiviral medications that can shorten the flu or make it less severe.

A Word From Verywell

For most people, the flu resolves on its own. Unfortunately, you might cough or just generally not feel well for up to two weeks after getting the flu. If you believe you or your child has the flu, reach out to your healthcare provider, who may be able to provide treatment options.