Small Trial Fails to Show Benefits of Echinacea to Treat Genital Herpes


Reviewed: Vonau B, Chard S, Mandalia S, Wilkinson D, Barton SE. Does the extract of the plant Echinacea purpurea influence the clinical course of recurrent genital herpes? International Journal of STD & AIDS 2001;12:154-8.

Genital herpes is caused by herpes simplex virus type 1 or type 2. The infection causes genital ulcerations that can recur after the initial infection has healed because the virus may remain latent for a period of time and then reactivate. The reactivation triggers are not fully understood, but appear to include other infections, localized trauma, exposure to ultraviolet light, and psychological stress.

Echinacea (Echinacea purpurea (L.) Moench, Asteraceae) grows in North America and was used by Native Americans for various medical problems, including mouth ulcers. This study cites several studies supporting the well-known immunostimulating effects of echinacea preparations.

Several anti-viral drugs are considered safe and effective for limiting the symptoms of genital herpes and reducing recurrences. However, some patients cannot take these drugs due to side effects or drug allergies; others report breakthrough recurrences of herpes while on long-term therapy. For these reasons, and because some consumers consider herbal medicine safer than pharmaceutical drugs, the authors report, some people use echinacea to prevent and treat genital herpes recurrences. However, no placebo-controlled, randomized, prospective studies have been published on the usefulness of E. purpurea extract for genital herpes.

This prospective, double-blind crossover study attempted to evaluate whether treatment with oral E. purpurea extract could reduce the frequency and severity of genital herpes recurrences. The product used (Echinaforce®, manufactured and supplied to the researchers by Bioforce, Switzerland) is an ethanolic extract made up of 95 percent E. purpurea aerial parts and 5 percent E. purpurea root. Dosage was 800 mg, twice daily.

Twenty-five subjects received the placebo and then echinacea (for 6 months each), while 25 other subjects received echinacea first and placebo second. The mean subject age was 36.5 years (range: 22-72 years), 24 men and 26 women. Subjects reported that they had their first genital herpes infection from 3 months to 20 years before the study began, and with a median of 7 recurrences per year.

At study entry, all subjects completed a physical examination, medical history, and psychological evaluation. During the study, subjects were assessed monthly and also as soon as pos-sible (within 72 hours) after onset of a new genital herpes recurrence. Subjects were asked to record their symptoms during recurrences, the occurrence of any other viral illnesses, their stress levels, and compliance with study medication. For each recurrence, subjects reported the duration and rated their pain by using a visual analogue scale.

Too few subjects completed the study to allow detection of significant differences at the level of statistical power selected (a power of 80 percent, to detect a difference of 20 percent in reduction of recurrence frequency). Of the 50 subjects, 19 (38 percent) dropped out; at least 47 were needed to complete the study to detect significant differences. The authors attribute the drop-out rate to the requirement for frequent study visits and blood samples.

After acknowledging some of their study's limitations, the authors conclude that they found no significant benefit from the plant and root extract of echinacea for reducing the frequency of genital herpes recurrences. They then make this somewhat surprising statement, "Given that there are safe and efficacious alternatives [i.e., pharmaceutical drugs], the value of further studies into its benefits for this indication seem unjustified." It is difficult to understand how the authors can dismiss future research in this area when this study's conclusions are so tentative, especially considering the lack of statistical power due to the high dropout rate.

One of HerbalGram's reviewers added the following comment on this point, "In the worst light, these researchers seem to have performed a study incapable of detecting a statistically significant difference and discarded as an artifact a trend in favor of a non-statistically significant difference. In addition, when the patients were asked (while still blinded) on which medication they fared better, 12 favored echinacea while only 5 favored placebo. Yet, the authors confidently state that no further studies are warranted!"

The reviewer concluded, "I'm sure that no one who takes or prescribes it for herpes thinks echinacea will have a huge effect. Anyone interested in 'natural' health would be doing multiple things to reduce recurrences. Thus, since the trial studied echinacea in isolation, it should be sensitive to a small effect in order to answer the pragmatic question, 'Would the addition of echinacea to the management of herpes be beneficial?' This trial wasn't sensitive to small effect (20 percent reduction of recurrence)."

2002 American Botanical Council.


By Christina Chase, M.S., R.D.

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