The flu, also known as influenza, is a highly contagious viral infection that affects your respiratory system, including your nose, throat, and lungs. You may get the flu when you come in contact with someone who is infected. You are the most contagious during the first three days of the infection.
Flu symptoms are often mistaken for the common cold. However, with the flu, the symptoms tend to develop rapidly and be more severe than cold symptoms.
Symptoms that may indicate you have the flu include: