The symptoms of the flu and first signs of the flu can vary from person to person depending on the strain of flu they have become infected with.
Some symptoms of the flu that you may experience during the onset of the flu are headaches, sore throat, fever and a runny nose.
Aside from those symptoms of the flu some other symptoms you may experience as the flu progresses are muscle aches, whole body aches, leg pain, back pain, nausea and sometimes even vomiting.
When you have the flu it will make your body weak and sometimes you won't be able to think clearly so your reaction time to things may be slow as well.
So if you have the flu it's best to not drive or operate any machinery and just stay home and get plenty of rest until you're feeling better.