Supplement Forms/Alternate Names:

Equisetum arvense, field horsetail, scouring horsetail, western horsetail


Horsetail is a short green plant that grows in most parts of the world. It has been used to ease swelling in the joints and increase urine flow. It can be taken as a pill, powder, or extract. Horsetail can also be made into a tea.


There aren’t any advised doses for horsetail.

What Research Shows

Not Enough Data to Assess

  • Rheumatoid arthritisA

Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.

Safety Notes

It is likely safe for most adults to take horsetail for a short time. Not enough studies have been done to say whether it is safe to take for a long period or by women who are pregnant or breastfeeding. B1


Talk to your doctor about any supplements or therapy you would like to use. Some can interfere with treatment or make conditions worse, such as:

  • People with HIV should talk to their doctors before taking horsetail. It may interact with their medicines.B2


A. Rheumatoid Arthritis

A1. Jiang X, Qu Q, et al. Horsetail mixture on rheumatoid arthritis and its regulation on TNF-α and IL-10. Pak J Pharm Sci. 2014;27(6):2019-2023.

B. Safety

B1. Klnçalp S, Ekiz F, et al. Equisetum arvense (Field Horsetail)-induced liver injury. Eur J Gastroenterol Hepatol. 2012 Feb;24(2):213-214.

B2. Cordova E, Morganti L, et al. Possible Drug-Herb Interaction between Herbal Supplement Containing Horsetail ( Equisetum arvense) and Antiretroviral Drugs. J Int Assoc Provid AIDS Care. 2017 Jan/Feb;16(1):11-13.

Last reviewed February 2020 by EBSCO NAT Review Board Eric Hurwitz, DC  Last Updated: 5/27/2020