An evidence-based systematic review of echinacea ( E. angustifolia DC, E. pallida, E. purpurea) by the natural standard research collaboration

A small clinical trial assessing the potential benefit of oral echinacea for recurrent herpes genitalis found no effect. Conclusions cannot be considered definitive without further trials. Vonau et al. conducted a randomized, placebo controlled, cross-over trial to evaluate the therapeutic use of echinacea for recurrent genital herpes. Fifty patients were randomly allocated to a treatment sequence of either echinacea extract (800 mg orally twice/day) for six months followed by placebo for six months, or vice versa. Number of recurrences and several indicators of disease status (Visual Analogue Scale of pain, CD4 counts, neutrophil counts) were assessed before and after treatments. No statistically significant differences were found between the groups. Although the sample size was relatively small, a relevant treatment benefit would likely have been detected if present.