Key Points about the Flu

  • The flu is a respiratory infection caused by the influenza virus.
  • Common symptoms of the flu include as fever, chills, coughing, sneezing, and a sore throat.
  • The flu can usually be treated at home with rest, fluids, and over-the-counter pain relievers.
  • Your doctor may prescribe an antiviral to alleviate symptoms and shorten the infection’s duration.
  • Some types of influenza can be prevented by getting a yearly flu vaccine.

If you are experiencing chest pain, are having trouble breathing, have symptoms that worsen over time, of if you are at risk of developing complications, call your doctor, as these could be signs of secondary infections that can be life-threatening.

Overview

The flu is an infection caused by the influenza virus. The virus affects the throat, nose and lungs, and often causes symptoms such as fever, chills, coughing, sneezing, and a sore throat.

Most cases of the flu go away on their own within two weeks, and can be treated at home with rest, fluids, and over-the-counter pain relievers. If you see a doctor about flu symptoms, you may be prescribed an antiviral to decrease the length and severity of your infection.

In some cases, however, the flu can lead to serious complications, particularly among people in young children, older adults, or people who are immunocompromised. Rare but severe complications can include pneumonia, sepsis, and multiple organ failure.

Call your doctor if you have chest pain, are having trouble breathing, have symptoms that worsen over time, of if you are at risk of developing complications.

Flu causes

Flu symptoms are caused by infection with one of several strains of the influenza virus. The virus can spread from person to person through:

  • Saliva
  • Direct skin contact
  • Airborne droplets from a cough or sneeze
  • Touching a surface such as a telephone or doorknob that has the virus on it

Flu risk factors

Anyone who comes into contact with the virus is at risk of becoming infected. You may be at an increased risk of developing complications from the flu, however, if you are:

  • over age 65
  • Under age 5
  • Pregnant
  • Immunocompromised
  • Obese
  • Living in a nursing home
  • Living with a chronic illness

Flu symptoms

Flu symptoms often appear suddenly, and may include:

  • Fever over 100 F
  • Body chills or body aches
  • Headaches
  • Sore throat
  • Coughing
  • Sneezing
  • Fatigue
  • Runny nose or stuffy nose

Children with the flu may also experience diarrhea and vomiting.

Flu complications

The flu can lead to usually mild complications such as:

  • Sinus infections
  • Ear infections

More serious and potentially life-threatening complications can also result from the flu, particularly in vulnerable populations such as young children and adults over age 65. Such complications may include:

  • Pneumonia
  • Sepsis
  • Myocarditis, or heart inflammation
  • Encephalitis, or brain inflammation
  • Inflammation of muscle tissues
  • Respiratory failure
  • Kidney failure

Flu prevention

Some forms of the flu can be prevented by:

  • Getting a flu shot each year
  • Practicing good hand hygiene
  • Avoiding contact with people infected with the flu

Flu diagnosis

When diagnosing the flu, your doctor will review your symptoms and conduct a physical examination. Your doctor may also provide a test called the rapid influenza diagnostics test, although results from this test are not always definitive.

Flu treatment

Most cases of the flu can be treated at home by:

  • Drinking lots of water and other hydrating liquids, such as soup and electrolyte drinks
  • Resting as much as you feel you need, and getting up when you feel you are able
  • Taking over-the-counter pain relievers as needed, such as ibuprofen or acetaminophen

If you see a doctor for the flu, your doctor may prescribe an antiviral medication to alleviate symptoms and shorten the duration of your infection. Antivirals are most effective when taken within two days of your initial symptoms.

To avoid spreading the flu to others, stay home until 24 hours after your fever has gone away.  

When to seek care

Call your doctor if:

  • You have symptoms of the flu, and have any risk factors for developing complications from the flu
  • Your immune system is compromised
  • You have a fever for longer than three or four days
  • You have chest pain
  • Your breathing is impaired
  • Your symptoms are getting worse, not better, over time

Next Steps

If your symptoms continue to worsen, you may have a secondary infection. See your doctor if symptoms do not improve, as your doctor can provide treatment for any additional infections.