What is it?
The chemicals in horsetail might have antioxidant and anti-inflammatory effects. They might also work like "water pills" (diuretics) and increase urination.
People use horsetail for fluid retention, urinary tract infections (UTIs), osteoporosis, loss of bladder control, and many other conditions, but there is no good scientific evidence to support these uses.
How effective is it?
There is interest in using horsetail for a number of purposes, but there isn't enough reliable information to say whether it might be helpful.
Is it safe?
When applied to the skin: There isn't enough reliable information to know if horsetail is safe or what the side effects might be.
Special precautions & warnings:Pregnancy and breast-feeding: There isn't enough reliable information to know if horsetail is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.
Alcohol use disorder: People with this condition are generally also thiamine deficient. Taking horsetail might make thiamine deficiency worse.
Allergies to carrots and nicotine: Some people with allergy to carrot might also have allergy to horsetail. Horsetail also contains small amounts of nicotine. People with nicotine allergy might have an allergic reaction to horsetail.
Low potassium levels (hypokalemia): Horsetail might lower potassium levels in the blood. Until more is known, use horsetail with caution if you are at risk for potassium deficiency.
Low thiamine levels (thiamine deficiency): Taking horsetail might make thiamine deficiency worse.
Are there interactions with medications?
- Efavirenz (Sustiva)
- Efavirenz is a drug used to treat HIV. Taking horsetail with efavirenz might reduce the effects of efavirenz. Talk with your healthcare provider before using horsetail if you are taking efavirenz.
- Taking horsetail might decrease how well the body gets rid of lithium. This could increase how much lithium is in the body and result in serious side effects. Talk with your healthcare provider before using this product if you are taking lithium. Your lithium dose might need to be changed.
- Medications for diabetes (Antidiabetes drugs)
- Horsetail might lower blood sugar levels. Taking horsetail along with diabetes medications might cause blood sugar to drop too low. Monitor your blood sugar closely.
- Medications for HIV/AIDS (Nucleoside reverse transcriptase inhibitors (NRTIs))
- Taking horsetail with NRTIs might reduce the effects of these drugs. Talk with your healthcare provider before using horsetail if you are taking an NRTI.
- Water pills (Diuretic drugs)
- Horsetail can decrease potassium levels. "Water pills" can also decrease potassium levels. Taking horsetail along with "water pills" might make potassium levels drop too low.
Are there interactions with herbs and supplements?
- Betel nut
- Horsetail and betel nut both reduce the amount of thiamine available for the body to use. Using these herbs together might increase the risk for thiamine deficiency.
- Chromium-containing herbs and supplements
- Horsetail contains chromium. Taking it with other supplements that contain chromium can increase the risk of chromium poisoning. Examples of supplements that contain chromium include bilberry, brewer's yeast, and cascara sagrada.
- Herbs and supplements that might lower blood sugar
- Horsetail might lower blood sugar. Taking it with other supplements with similar effects might lower blood sugar too much. Examples of supplements with this effect include aloe, bitter melon, cassia cinnamon, chromium, and prickly pear cactus.
- Horsetail contains large amounts of silicon. Taking horsetail along with silicon supplements might increase the risk of adverse effects from silicon.
- Crude horsetail contains a chemical that breaks down thiamine. Taking horsetail might cause thiamine deficiency.
Are there interactions with foods?
- There are no known interactions with foods.
How is it typically used?
To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.
- Bates D, Duong TB, Kheyson S, Moore K. Hyponatremia Secondary to Decreased Oral Intake and SIADH and Possibly Exacerbated by Horsetail (Equisetum arvense). Can J Hosp Pharm 2021;74:386-389. View abstract.
- Waterstradt A, Winker M, Zimmermann-Klemd AM, et al. Silicon Resorption from Equisetum arvense Tea - A Randomized, Three-Armed Pilot Study. Planta Med 2021. View abstract.
- Carneiro DM, Jardim TV, Araújo YCL, et al. Antihypertensive effect of Equisetum arvense L.: a double-blind, randomized efficacy and safety clinical trial. Phytomedicine 2022;99:153955. View abstract.
- Health Canada. Organism-Equisetum arvense. Available at: http://webprod.hc-sc.gc.ca/nhpid-bdipsn/ingredReq.do?id=6117&lang=eng. Accessed 21-July 2021.
- Vieira GT, de Oliveira TT, Carneiro MAA, et al. Antidiabetic effect of Equisetum giganteum L. extract on alloxan-diabetic rabbit. J Ethnopharmacol. 2020;260:112898. View absract.
- Popovych V, Koshel I, Malofiichuk A, et al. A randomized, open-label, multicenter, comparative study of therapeutic efficacy, safety and tolerability of BNO 1030 extract, containing marshmallow root, chamomile flowers, horsetail herb, walnut leaves, yarrow herb, oak bark, dandelion herb in the treatment of acute non-bacterial tonsillitis in children aged 6 to 18?years. Am J Otolaryngol. 2019;40:265-273. View abstract.
- Schoendorfer N, Sharp N, Seipel T, Schauss AG, Ahuja KDK. Urox containing concentrated extracts of Crataeva nurvala stem bark, Equisetum arvense stem and Lindera aggregata root, in the treatment of symptoms of overactive bladder and urinary incontinence: a phase 2, randomised, double-blind placebo controlled trial. BMC Complement Altern Med. 2018;18:42. View abstract.
- García Gavilán MD, Moreno García AM, Rosales Zabal JM, Navarro Jarabo JM, Sánchez Cantos A. Case of drug-induced acute pancreatitis produced by horsetail infusions. Rev Esp Enferm Dig. 2017 Apr;109:301-304. View abstract.
- Cordova E, Morganti L, Rodriguez C. Possible Drug-Herb Interaction between Herbal Supplement Containing Horsetail (Equisetum arvense) and Antiretroviral Drugs. J Int Assoc Provid AIDS Care. 2017;16:11-13. View abstract.
- Radojevic ID, Stankovic MS, Stefanovic OD, Topuzovic MD, Comic LR, Ostojic AM. Great horsetail (Equisetum telmateia Ehrh.): Active substances content and biological effects. EXCLI J. 2012 Feb 24;11:59-67. View abstract.
- Ortega García JA, Angulo MG, Sobrino-Najul EJ, Soldin OP, Mira AP, Martínez-Salcedo E, Claudio L. Prenatal exposure of a girl with autism spectrum disorder to 'horsetail' (Equisetum arvense) herbal remedy and alcohol: a case report. J Med Case Rep. 2011 Mar 31;5:129. View abstract.
- Klnçalp S, Ekiz F, Basar Ö, Coban S, Yüksel O. Equisetum arvense (Field Horsetail)-induced liver injury. Eur J Gastroenterol Hepatol. 2012 Feb;24:213-4. View abstract.
- Gründemann C, Lengen K, Sauer B, Garcia-Käufer M, Zehl M, Huber R. Equisetum arvense (common horsetail) modulates the function of inflammatory immunocompetent cells. BMC Complement Altern Med. 2014 Aug 4;14:283. View abstract.
- Farinon M, Lora PS, Francescato LN, Bassani VL, Henriques AT, Xavier RM, de Oliveira PG. Effect of Aqueous Extract of Giant Horsetail (Equisetum giganteum L.) in Antigen-Induced Arthritis. Open Rheumatol J. 2013 Dec 30;7:129-33. View abstract.
- Carneiro DM, Freire RC, Honório TC, Zoghaib I, Cardoso FF, Tresvenzol LM, de Paula JR, Sousa AL, Jardim PC, da Cunha LC. Randomized, Double-Blind Clinical Trial to Assess the Acute Diuretic Effect of Equisetum arvense (Field Horsetail) in Healthy Volunteers. Evid Based Complement Alternat Med. 2014;2014:760683. View abstract.
- Henderson JA, Evans EV, and McIntosh RA. The antithiamine action of Equisetum. J Amer Vet Med Assoc 1952;120:375-378.
- Corletto F. [Female climacteric osteoporosis therapy with titrated horsetail (Equisetum arvense) extract plus calcium (osteosil calcium): randomized double blind study]. Miner Ortoped Traumatol 1999;50:201-206.
- Tiktinskii, O. L. and Bablumian, I. A. [Therapeutic action of Java tea and field horsetail in uric acid diathesis]. Urol.Nefrol.(Mosk) 1983;3:47-50. View abstract.
- Graefe, E. U. and Veit, M. Urinary metabolites of flavonoids and hydroxycinnamic acids in humans after application of a crude extract from Equisetum arvense. Phytomedicine 1999;6:239-246. View abstract.
- Agustin-Ubide MP, Martinez-Cocera C, Alonso-Llamazares A, et al. Diagnostic approach to anaphylaxis by carrot, related vegetables and horsetail (Equisetum arvense) in a homemaker. Allergy 2004;59:786-7. View abstract.
- Revilla MC, Andrade-Cetto A, Islas S, Wiedenfeld H. Hypoglycemic effect of Equisetum myriochaetum aerial parts on type 2 diabetic patients. J Ethnopharmacol 2002;81:117-20. View abstract.
- Lemus I, Garcia R, Erazo S, et al. Diuretic activity of an Equisetum bogotense tea (Platero herb): evaluation in healthy volunteers. J Ethnopharmacol 1996;54:55-8. View abstract.
- Perez Gutierrez RM, Laguna GY, Walkowski A. Diuretic activity of Mexican equisetum. J Ethnopharmacol 1985;14:269-72. View abstract.
- Fabre B, Geay B, Beaufils P. Thiaminase activity in equisetum arvense and its extracts. Plant Med Phytother 1993;26:190-7.
- Henderson JA, Evans EV, McIntosh RA. The antithiamine action of Equisetum. J Am Vet Med Assoc 1952;120:375-8. View abstract.
- Ramos JJ, Ferrer LM, Garcia L, et al. Polioencephalomalacia in adult sheep grazing pastures with prostrate pigweed. Can Vet J 2005;46:59-61. View abstract.
- Husson GP, Vilagines R, Delaveau P. [Antiviral properties of various extracts of natural origin]. Ann Pharm Fr 1986; 44:41-8. View abstract.
- Do Monte FH, dos Santos JG Jr, Russi M, et al. Antinociceptive and anti-inflammatory properties of the hydroalcoholic extract of stems from Equisetum arvense L. in mice. Pharmacol Res 2004;49:239-43. View abstract.
- Correia H, Gonzalez-Paramas A, Amaral MT, et al. Characterisation of polyphenols by HPLC-PAD-ESI/MS and antioxidant activity in Equisetum telmateia. Phytochem Anal 2005;16:380-7. View abstract.
- Langhammer L, Blaszkiewitz K, Kotzorek I. Evidence of toxic adulteration of equisetum. Dtsch Apoth Ztg 1972;112:1751-94.
- Dos Santos JG Jr, Blanco MM, Do Monte FH, et al. Sedative and anticonvulsant effects of hydroalcoholic extract of Equisetum arvense. Fitoterapia 2005;76:508-13. View abstract.
- Sakurai N, Iizuka T, Nakayama S, et al. [Vasorelaxant activity of caffeic acid derivatives from Cichorium intybus and Equisetum arvense]. Yakugaku Zasshi 2003;123:593-8. View abstract.
- Oh H, Kim DH, Cho JH, Kim YC. Hepatoprotective and free radical scavenging activities of phenolic petrosins and flavonoids isolated from Equisetum arvense. J Ethnopharmacol 2004;95:421-4.. View abstract.
- Sudan BJ. Seborrhoeic dermatitis induced by nicotine of horsetails (Equisetum arvense L.). Contact Dermatitis 1985;13:201-2. View abstract.
- Piekos R, Paslawska S. Studies on the optimum conditions of extraction of silicon species from plants with water. I. Equisetum arvense L. Herb. Planta Med 1975;27:145-50. View abstract.
- Health Canada. Labelling Standard: Mineral Supplements. Available at: http://www.hc-sc.gc.ca/dhp-mps/prodpharma/applic-demande/guide-ld/label-etiquet-pharm/minsup_e.html (Accessed 14 November 2005).
- Vimokesant S, Kunjara S, Rungruangsak K, et al. Beriberi caused by antithiamin factors in food and its prevention. Ann N Y Acad Sci 1982;378:123-36. View abstract.
- Lanca S, Alves A, Vieira AI, et al. Chromium-induced toxic hepatitis. Eur J Intern Med 2002;13:518-20. View abstract.