Influenza, commonly known as the flu, is an acute respiratory infectious disease caused by the influenza virus. What are the symptoms after contracting the flu? Typically, the onset of influenza is quite sudden, and symptoms such as chills, high fever, headache, dizziness, body aches, and fatigue can appear quickly. Generally, the symptoms in the nasopharyngeal area are relatively mild and prolonged, and may include sore throat, runny nose, tearing, coughing, etc. After contracting the flu, it is important to actively cooperate with medical treatment and also to ensure isolation to prevent infecting others.