Influenza is a contagious viral infection caused by influenza A and B viruses. It affects the nose, throat, and sometimes the lungs, causing symptoms that appear suddenly, including high fever, cough, fatigue, and muscle aches. A seasonal illness, influenza causes symptoms such as sudden onset fever, chills, muscle aches, weakness, dry cough, sore throat, and nasal congestion. Hoarseness may also develop in later days.

Influenza generally resolves on its own with home remedies; however, medical attention may be necessary if symptoms worsen or become severe. Depending on the patient's condition, various treatment methods may be applied. In addition to treatment, a crucial preventative measure is the annual influenza vaccination.