Find information on medical topics, symptoms, drugs, procedures, news and more, written in everyday language.

* This is the Consumer Version. *

Influenza (Flu)

by Craig R. Pringle, BSc, PhD

Influenza (flu) is infection of the lungs and airways with one of the influenza viruses. It causes a fever, runny nose, sore throat, cough, headache, muscle aches (myalgias), and a general feeling of illness (malaise).

  • The virus is spread by inhaling droplets coughed or sneezed out by an infected person or by having direct contact with an infected person's nasal secretions.

  • Influenza often starts with chills, followed by a fever, muscle aches, headache, a sore throat, a cough, a runny nose, and a general feeling of illness.

  • People can often diagnose influenza themselves based on symptoms, but sometimes samples of blood or respiratory secretions must be analyzed to identify the virus.

  • An annual influenza vaccination is the best way to prevent influenza.

  • Resting, drinking plenty of fluids, and avoiding exertion can help, as can taking pain relievers, decongestants, and sometimes antiviral drugs.

Influenza is distinctly different from the common cold (see Common Cold). It is caused by a different virus and produces symptoms that are more severe. Also, influenza affects cells much deeper down in the respiratory tract.

The influenza virus is spread by inhaling droplets that have been coughed or sneezed out by an infected person or by having direct contact with an infected person's nasal secretions. Infection may be spread when people handle household articles that have been in contact with an infected person or an infected person's secretions.

Resources In This Article

Drugs Mentioned In This Article

  • Generic Name
    Select Brand Names
  • No US brand name
  • RELENZA
  • TAMIFLU
  • ADVIL, MOTRIN IB
  • TYLENOL