In the treatment of acute respiratory infection, the activi-ty of Echinacea is often enhanced by Chinese herbal mixtures traditionally used for treating fever. My favorite is called Isatis Formula. It is commercially available as an alcohol extraction of the leaves and roots of six plants. The dose is one to three drop-persful three times a day. During heavy flu seasons, over three quarters of my patients taking the Echinacea and Isatis combina-tions have made statements like, "Everyone around me was sick for weeks, taking antibiotics. I usually get sick for three weeks with the flu, but I was better within a few days after starting these herbs."

Astragalus root is a component of many traditional Chinese herbal formulas, generally considered to be a strong tonic and reistance-builder. Contemporary studies reveal that Astragalus can increase natural killer cell activity. I often recommend Astragalus for maintenance therapy of people with chronic or recurrent infectious diseases of any type, because of its high margin of safety.

(6) Mushrooms. Fungal extracts are widely employed in traditional Chinese medicine. Shiitake (Lentinus edodes) and Reishi (Ganoderma lucidum) contain polysaccharides that increase natural killer cell activity and inhibit tumor growth in animals and in humans. Like Astragalus, Shiitake and Reishi are used in contem-porary Chinese medicine as Fu Zheng remedies, which means they "support the normal", stimu-lating health, rather than being used as medication to treat sickness. A dose which stimulates immune responses is 900 mg per day of each. For people with severe allergies, it is advisable to use Reishi alone, as Reishi may inhibit allergic reactivity and Shiitake may increase it.