Influenza, commonly known as the flu, is a contagious illness caused by viruses that infect the nose, throat and lungs, sometimes in similar ways to a common cold. Flu symptoms include fever, body aches, chills, headache, congestion and coughing. However, the flu can also cause severe illness and even lead to death — especially in babies, elderly and sick people. The flu is much more dangerous than a cold, and flu symptoms are more severe.
