If you're feeling symptoms you are already sick and can do nothing. Symptoms of sickness are the result of your immune system trying to fight it off.
You can do nothing but use antibiotics in a bacterial related disease, but even then that is no guarantee and on NO CIRCUMSTANCES should you self-diagnose antibiotics. ALWAYS VISIT A DOCTOR.
The only thing you can do is to keep yourself comfortable and take care of your body as normal. Consume plenty of fluids (this includes foods like soup, not just water), maintain a healthy balanced diet as much as you can, keep warm and get sleep.
You'll fight off flu eventually.
And although it's already been stated here, it's worth noting to never take antibiotics for a viral infection. They serve no function as viruses live inside your own cells during infection, which are immune to antibiotics. You serve nothing but to promote drug resistance in strains of bacteria in your body. They might not be harmful strains, but they can transfer the resistance genes to other harmful strain.
A careful and informed approach to antibiotic use does save lives, yours and many others.
