Mixed doses and differing preparations of echinacea have complicated the results of many clinical trials. Yet, for the first time, despite the heterogeneity of tested preparations, a recent meta-analysis of high quality studies shows echinacea can reduce recurrent respiratory tract infections (RRTIs) by 50% when compared to a placebo.
Using a methodological quality scaling system, independent reviewers analysed human clinical trials accessed from various databases. The aim was to review the risk of RRTIs and complications following echinacea use over 2-4 months. Of the trials found, only six met the criteria and high quality Jada score of ≥4. The included trials were performed under randomised, placebo-controlled conditions on healthy individuals.
The results showed that in 1440 treatment participants, both Echinacea angustifolia and Echinacea purpurea, taken for up to four months in varying doses and preparations, had a statistically significant effect on the long-term management of RRTIs and complications compared to placebo. The greatest benefit was found in those who had higher stress levels or a reduced immune status.
Although the long-term use of echinacea was found more beneficial than acute therapy, the two studies that had a 50% reduction in RTI recurrences used the herb continuously for 3-4 months and doubled the dose during acute phases. This combined preventative and acute protocol may optimise therapy, even with differing doses and preparations.
The researchers suggested ‘increased dosing upon treatment of an initial ‘‘trigger’’ infection (in addition to basic prevention) could reduce inflammatory tissue damage (airway reactiveness), which otherwise would lead to further infections and complications.’
Subgroup analysis revealed alcoholic extracts statistically outperformed pressed juice preparations. But due to the limited number of trials the authors noted that future research needs to focus on chemically standardised extracts.
Complications, such as pneumonia, otitis media/externa and tonsillitis/pharyngitis, along with antibiotic use, were also reduced by an overall 50%, while safety profile data showed mild and transient effects, similar to placebo, with good to very good tolerability.
A 2014 Cochrane review supported a small reduction in the rate of colds using echinacea prophylactically, compared to placebo.
Another 2015 study found an echinacea drink was as effective as an antiviral medication in the early stages of influenza.
Schapowal A, Klein P, Johnston SL. Echinacea reduces the risk of recurrent respiratory tract infections and complications: a meta-analysis of randomized controlled trials. Adv Ther 2015;32(3):187-200. [Abstract]
Karsch-Völk M, Barrett B, Linde K. Echinacea for preventing and treating the common cold. JAMA 2015;313(6):618-619. [Full Text]
Rauš K, Pleschka S, Klein P, et al. Effect of an echinacea-based hot drink versus oseltamivir in influenza treatment: a randomized, double-blind, double-dummy, multicenter, noninferiority clinical trial. Curr Ther Res Clin Exp 2015;77:66-72. [Full Text]