Evidence Level
Moderate
Echinacea research has produced mixed results largely due to variability in species, plant parts, and preparations used across studies. Shah et al. (2007) conducted a meta-analysis of 14 RCTs showing significant benefits, while a later Cochrane review by Karsch-Volk et al. (2014) was more conservative, noting modest benefits that did not always reach statistical significance. The best evidence supports Echinacea purpurea aerial parts (particularly the fresh-pressed juice preparation Echinaforce) for reducing cold incidence and duration. The immunological mechanisms are well-characterized, with alkamides and polysaccharides activating macrophages through CB2 and TLR receptors.