How does Echinacea affect the common cold?
Echinacea is an herb that is found in the United States and Canada. There are 9 different species. The most commonly used and most potent species is Echinacea purpurea. Traditionally, Echinacea has been used to treat infections. It is theorized that Echinacea may demonstrate immune-stimulating activity.
The effectiveness of Echinacea for preventing and treating the common cold remains controversial. Some research studies have shown benefit, while others have not. One recent study may help to clarify the role of Echinacea in preventing and treating infections. The study combined and evaluated data from 14 separately conducted research trials of Echinacea. The analysis showed that Echinacea decreased the odds of developing a cold by 58% and decreased the duration of a cold by 1.4 days. However, this type of study is difficult to interpret because each individual study used different species, doses, and lengths of treatment of Echinacea. Therefore, it is still unclear what dose and duration of treatment with Echinacea is optimal for preventing and treating colds