Home / Ingredients / Horsetail (Equisetum arvense)
Evidence reviewed: 2026-10-02
Small human trials suggest diuretic and blood-pressure effects for standardized extracts, but the evidence base is limited and does not support broad or finished-product claims.
A randomized crossover trial in 36 healthy men found an acute diuretic effect with a standardized dried extract. A separate small randomized trial in stage-I hypertension reported blood-pressure reductions similar to hydrochlorothiazide over three months. These findings require replication and should not be generalized across unstandardized horsetail products.
The human trials used a standardized dry Equisetum arvense extract at 900 mg/day. One was a four-day crossover diuretic study in healthy men; the other was a three-month trial in 58 people with stage-I hypertension.
The small trials reported few minor adverse events and no major laboratory toxicity over the studied periods. LiverTox notes rare reports in which horsetail was implicated in herb-associated liver injury, but causal detail is limited.
V-ITAREN lists horsetail without dose or extract standardization. The 900 mg/day standardized-extract trial results cannot be assigned directly to this finished product.
Important: Ingredient-level evidence is not proof that a finished product has the same effect. Dose, form, population, duration, and formulation must match.
For informational purposes only; not individualized medical advice.