If the flu has started then there is nothing you can do because flus are caused by viruses and viruses do not leave their hosts until they complete their course.

Ofcourse you could try something radical and begin heavy exercise because when I am about to get the flu I do that and many times I am saved. Some other people have also told me it works.

And if you are not the radical type then you will just have to bear a week of runny nose, sneezes, and a full head.