Antihypertensive effect of Equisetum arvense L.: a double-blind, randomized efficacy and safety clinical trial.

Background: Equisetum arvense L. (EA) is a traditional phytomedicine used as a diuretic agent worldwide and regulated strictly by European Medicine Agency (EMA) and Brazilian National Health Surveillance Agency (ANVISA). However, few studies evaluating its efficacy and safety have been published and no clinical trial assessing its antihypertensive effect has been reported to date.

Randomized, Double-Blind Clinical Trial to Assess the Acute Diuretic Effect of Equisetum arvense (Field Horsetail) in Healthy Volunteers.

In this double-blind, randomized clinical trial, 36 healthy male volunteers were randomly distributed into three groups (n = 12) that underwent a three-step treatment. For four consecutive days, we alternately administered a standardized dried extract of Equisetum arvense (EADE, 900 mg/day), placebo (corn starch, 900 mg/day), or hydrochlorothiazide (25 mg/day), separated by a 10-day washout period. Each volunteer served as his own control, and the groups' results were compared.