From The March 1999 Issue of Nutrition Science News
People can't avoid coming in contact with influenza, but if they treat symptoms promptly with the following antiviral and immune-boosting herbs, they might have an easier time of it.
Several lab studies indicate that the various echinacea species (E. angustifolia, E. pallida and E. purpurea) stimulate white blood cell activity, increase the body's production of the natural antiviral substance interferon and inhibit influenza viruses.
For instance, in a German clinical trial, researchers randomly assigned 180 people who had the flu to take either placebo, 450 mg (90 drops) a day of an E. purpurea root alcohol extract or 900 mg a day of the extract. The 450-mg dose proved no more effective than placebo. Those taking 900 mg a day, however, reported a significant reduction in flu symptoms such as weakness, chills, sweating, sore throat, headaches, and muscle and joint aches. 
Elderberry (Sambucus nigra) also eases flu symptoms. In a trial of 27 recently infected people, 93.3 percent of those who took elderberry extract (two tablespoons a day for children, four for adults) were much improved after two days, compared with 25 percent of the placebo group. 
1. Bodinet C, et al. Host-resistance increasing activity of root extracts from echinacea species Planta Medica 1993; 59 (Suppl): A672
2. Zakay-Rones Z, et al.
Inhibition of several strains of influenza virus in vitro and reduction of symptoms by an elderberry extract (Sambucus nigra) during an outbreak of influenza in Panama
J Alternative and Complementary Med 1995; 1 (4): 361-369