[Yaa101]

With Flu your bones or muscles ache or your belly feels like it falls off. When bad, you have all symptoms. Worse is when attracting lung inflammation, that feels as if you are constantly drowning. All of this with high fever or even worse, cold fever.

[nradov]

Those symptoms may or may not occur depending on the influenza strain and the individual patient. Many influenza cases are entirely asymptomatic.