Influenza, commonly referred to as “the flu,” is a highly contagious respiratory infection caused by the influenza virus.

According to the Centers for Disease Control and Prevention (CDC), an uncomplicated influenza infection will last from three to seven days in most people, including children. However, a cough and feelings of weakness or fatigue can last for two weeks or longer.

Some people are at an increased risk for developing flu-related complications. These can include:

These complications can be due to influenza virus in itself or because of a secondary bacterial infection. Serious flu-related complications can lead to hospitalization and even death.

Additionally, flu infection may make preexisting conditions worse. For example, if you have asthma, you may experience more severe asthma attacks while you have the flu.

You’re at increased risk for developing flu-related complications if you:

  • are 65 years old or older
  • are younger than 5 years old and particularly younger than 2 years old
  • are of Native American (American Indian or Alaska Native) descent
  • are pregnant or two weeks postpartum
  • are extremely obese (BMI of 40 or more)
  • live in a nursing home or long-term care facility
  • have a weakened immune system, such as the kind seen in people with cancer or HIV
  • have a chronic illness, such as asthma, diabetes, or COPD
  • have a liver or kidney disorder

Do some strains of the flu last longer than other strains?

Although different influenza strains don’t generally affect the duration of illness, some strains (and subtypes of influenza A, like H3N2) can cause more severe illness than others.

According to the CDC, influenza A (H3N2) viruses have been associated with more hospitalizations and deaths in children and the elderly than other human influenza subtypes or strains, such as influenza A (H1N1) and influenza B.

Additionally, vaccine effectiveness for influenza A (H3N2) viruses has been generally lower.

Flu vs. cold duration

Despite having some overlapping symptoms, colds and the flu are two separate illnesses. Colds are typically milder than the flu. Cold symptoms will typically resolve in about 7 to 10 days and tend to not come on as fast as the flu. Flu symptoms may last for a couple of weeks.

Learn more about the differences between a cold and the flu.

It may take one to four days after exposure to the influenza virus for symptoms to develop.

If you have the flu, you’ll be contagious one day before developing symptoms and up to five to seven days after becoming ill.

Younger children or people with a weakened immune system may be contagious for longer.

The influenza virus can also survive on surfaces, such as doorknobs and tables, for up to 24 hours. Viruses live longer on materials such as stainless steel, plastic, and other hard surfaces.

To avoid transmitting the virus to others, wash your hands frequently and avoid touching your face or mouth.

If you’re sick, be sure to drink plenty of liquids and get plenty of rest. You can also take over-the-counter pain and fever relievers, such as ibuprofen (Advil) or acetaminophen (Tylenol), to help relieve your symptoms.

Stay at home while you’re sick and for at least 24 hours after your fever has gone down.

In some cases, your doctor may prescribe an antiviral medication. Antiviral medications can reduce the length of your illness and may help prevent complications. They don’t kill the influenza virus, however.

Antiviral medications must be taken within 48 hours of the onset of symptoms in order to be effective.

Common antiviral prescriptions include:

The U.S. Food and Drug Administration (FDA) also approved a new medication called baloxavir marboxil (Xofluza) in October 2018.

Receiving the flu vaccine can help prevent influenza infection from occurring in the first place. The vaccine won’t give you the flu.

There isn’t current scientific evidence supporting the effectiveness of natural products or home remedies against the flu.

Most flu symptoms will typically resolve within a week. However, the flu can cause serious complications in groups with known risk factors or people who have preexisting conditions.

If you or your child experience any of the following symptoms, seek medical attention immediately:

Adults

  • trouble breathing or shortness of breath
  • pressure or pain in chest or abdomen
  • dizziness that comes on suddenly
  • confusion
  • vomiting
  • symptoms that seem to improve, but then return or worsen

Infants and children

  • trouble breathing, or breathing quickly
  • not getting enough fluids
  • not being able to eat
  • not waking up
  • not interacting or not wanting to be held
  • skin that’s blue in color
  • fever that comes with a rash
  • fewer wet diapers than usual
  • symptoms that seem to improve, but then return or worsen

If you come down with the flu, your symptoms will typically resolve on their own within a week. Prescribed antiviral medication may reduce this duration.

But if you have a high risk for complications or start to experience the more severe symptoms outlined above, contact your doctor right away.