Many herbalists recommend goldenseal for flu. Echinacea is also said to shorten symptoms when taken at the start of a cold or flu. But echinacea probably won't help if taken constantly over a long period of time. Doses of 500 mg four times a day may shorten cold symptoms by about a day or so. The jury is still out on whether vitamin C works as well for the flu as it does for colds.
Flu can cause fever, and fever is dehydrating.
Drinking a lot of fluids will help move the virus out of your system. Hot fluids also relieve sore throat, nasal congestion, and cough. No matter what your favorite remedy is, a cold or flu will still have to run its course. Save your body's energy for your immune system. Grab that book you've been meaning to read, snuggle in comfortably, and get plenty of rest.