Influenza (flu) can cause mild to severe illness, and at times can lead to death. Flu symptoms usually come on suddenly. People who have flu often feel some or all of these symptoms:
fever* or feeling feverish/chills
runny or stuffy nose
muscle or body aches
some people may have vomiting and diarrhea, though this is more common in children than adults.
*It’s important to note that not everyone with flu will have a fever.