Echinacea is most commonly used to reduce the duration and severity of an upper respiratory tract infection, aka the "common cold.” For those people echinacea has helped, it is thought to stimulate the function of immune cells, particularly natural killer cells (2). So echinacea doesn’t kill the cold virus directly, rather it stimulates your immune system to fend it off.
Also note, echinacea has been shown most effective for treating a cold, not preventing a cold. However, one study showed regular use of echinacea for four months over the winter decreased the number of colds by 21% compared with a placebo, a statistically significant difference.
To treat a cold, many doctors recommend to use echinacea for a total of seven to ten days.
What Form of Echinacea is Proven Effective?
Echinacea is a wildflower so different parts of the plant (leaves, flower, and root) have been studied for the medicinal use. Fresh pressed juice of echinacea flowers (E. purpurea) preserved with alcohol, and tinctures of echinacea root (E. pallida) are the forms most commonly studied and proven effective. Several trials have found echinacea root tinctures, in combination with wild indigo, boneset, and homeopathic arnica reduce symptoms of the common cold (3). Encapsulated echinacea may also be effective using the root of E. pallida (4).
Bottom Line: As you can suspect, additional research is needed in this area; however, there has been a lot of research with promising results, so if you do catch a cold, it sure wouldn’t hurt to try echinacea.
In Health and Happiness,
Kelly Harrington, MS, RDN
Registered Dietitian Nutritionist for Healthy Goods
2. See DM, Broumand N, Sahl L, Tilles JG. In vitro effects of echinacea and ginseng on natural killer and antibody-dependent cell cytotoxicity in healthy subjects and chronic fatigue syndrome or acquired immunodeficiency syndrome patients. Immunopharmacology 1997;35:229–35.
3. Melchart D, Linde K, Worku F, et al. Immunomodulation with echinacea—a systematic review of controlled clinical trials. Phytomedicine 1994;1:245–54 [review].
4. Dorn M, Knick E, Lewith G. Placebo-controlled, double-blind study of Echinacea pallidae radix in upper respiratory tract infections. Compl Ther Med 1997;5:40–2.