Symptoms of influenza, a sudden onset illness caused by the influenza virus, include high fever, chills, body aches, headache, fatigue, sore throat, dry cough, and less commonly, stuffy nose. Symptoms typically appear 1-3 days after infection, with fever and muscle aches less likely after day 4.

Influenza symptoms include:

* High fever
* Chills and shivering
* Cough
* Sore throat
* Body, muscle, and joint aches
* Fatigue and weakness
* Runny or stuffy nose
* Sneezing
* Chest discomfort and pressure
* Headache
* Shortness of breath
* Decreased appetite
* Nausea and vomiting (especially in children)