Flu B Symptoms 2024. Flu, also called influenza, is an infection of the nose, throat and lungs, which are part of the respiratory system. If you do get sick with the flu, the most common symptoms include a sudden onset of fever, chills, muscle aches, fatigue and respiratory ailments, such as a cough or sore.

Flu, also called influenza, is an infection of the nose, throat and lungs, which are part of the respiratory system. The flu is a common respiratory illness you get from the influenza virus.