7. You Have a High or Persistent Fever

A fever is an indication that your body is fighting of some sort of infection. Of course, in the case of the regular flu, this is a good thing, but if the fever seems too high or doesn’t go away in a short while (at least 3 days), you should consult your doctor about it. This is because it could allude to your body fighting much more serious problem than the regular flu – like meningitis, pneumonia, a sinus infection, a viral infection – or even cancers like lymphoma.