Echinacea species belong to the aster family (Asteraceae) that originated in eastern North America. Of the nine identified species, only three are used as medicine.
The roots and herbs of the species have been studied for potential immune benefits
Echinacea has been taken by mouth in Europe and the United States to help prevent or treat the common cold. In the United States, echinacea sales are thought to make up 10 percent of the dietary supplement market. Although much research has been done on the potential cold-fighting effects of echinacea, results are conflicting. There have been reports of a lack of benefit and rash caused by echinacea in children.
Early studies looking at the potential benefits of echinacea for herpes and radiation poisoning have found a lack of evidence. Applying echinacea juice to the skin has been suggested for wound healing, and taking echinacea by mouth or injecting it has been suggested for vaginal yeast infections. However, clear evidence is lacking in these areas.
Echinacea use has been discouraged in people who have autoimmune disease. However, more research is needed before further conclusions can be made.