A common, sometimes deadly viral infection of the nose, throat and lungs, also called flu.

Influenza, also called flu, affects the lungs, nose and throat. It is spread from person to person through respiratory droplets. Most people with the flu get better on their own. But influenza and its complications can be deadly to some people, including young children and older adults.

Symptoms tend to come on suddenly and include fever, muscle aches, chills and sweats, headache, tiredness, and runny or stuffy nose. Children also may have vomiting and diarrhea.

Treatment for influenza may include antiviral medicines. Treatment for symptoms includes drinking liquids, taking pain relievers for fever and headache, and resting. Seasonal flu vaccinations help prevent infection.