2024 Flu Symptoms And Duration. Flu, also called influenza, is an infection of the nose, throat and lungs, which are part of the respiratory system. Seasonal influenza (the flu) is an acute respiratory infection caused by influenza viruses.

Arm soreness, redness or swelling lasting a couple of days. Symptoms often include fever, head and body aches, coughing and a stuffy or runny nose.