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Scientific Name(s): Equisetum arvense L., Equisetum myriochaetum
Common Name(s): Bottle brush, Dutch rushes, Horse willow, Mexican giant horsetail, Paddock-pipes, Pewterwort, Scouring rush, Shave grass, Toadpipe

Medically reviewed by Last updated on Nov 22, 2022.

Clinical Overview


Horsetail has traditionally been used as a diuretic, an astringent to stop bleeding and stimulate the healing of wounds and burns, and as a cosmetic component. In addition, it has been used for the treatment of tuberculosis and for kidney and bladder ailments (eg, urethritis, cystitis with hematuria); however, clinical trials are lacking to support these uses. Clinical data demonstrates a hypoglycemic effect with the use of E. myriochaetum and efficacy in treating brittle nails with use of E. arvense.


Equisetum palustre products are contraindicated for use in humans. Brittle nails: A formulation containing E. arvense applied topically every night for 28 days or every other day for 14 days has been used to strengthen fingernails in clinical trials. Diuretic: A dry extract of the aerial parts of E. arvense containing 0.026% total flavonoids has been administered as 300 mg orally 3 times daily. Type 2 diabetes: A water extract of a related species of horsetail (E. myriochaetum) as a single oral dose of 0.33 g/kg has been used in a clinical study. Wound healing: An E. arvense 3% ointment applied topically every 12 hours for 10 days has been used following episiotomy in postpartum mothers.


Horsetail has been listed as an herb of undefined safety by the US Food and Drug Administration (FDA). Horsetail remedies prepared from E. arvense are generally considered safe when used properly. However, another species of horsetail, E. palustre, is poisonous to horses and contraindicated for use in humans.


Avoid use. Information regarding safety and efficacy in pregnancy and lactation is lacking.


The therapeutic effect of efavirenz may be diminished by horsetail.

Adverse Reactions

Documented adverse effects possibly associated with horsetail include acute pancreatitis and an isolated incident of headache.


Horsetail has been listed as an herb of undefined safety by the FDA. Horsetail remedies prepared from E. arvense are generally considered safe when used properly. However, another species of horsetail, E. palustre, is poisonous to horses and contraindicated for use in humans. E. arvense may be toxic, especially in cases of underlying liver disease. There have been reports of children being poisoned by using the stems as blowguns or whistles.

Scientific Family

  • Equisetaceae


E. arvense is native to Europe, North America, North Africa, and Northern AsiaChevalier 1996 and grows best in moist and shady areas.Weiss 1992 Horsetail is a pteridophyte more closely related to ferns than to flowering plants; it produces spore sacs that are visible from March through September.Hallowell 1994 The plant is a small, deep-rooted, rush-like perennial that grows about 0.3 m in height. It has hollow, pointed stems, scale-like leaves, and no flowers. Mexican giant horsetail (E. myriochaetum) is a species of horsetail native to regions of South America.Revilla 2002


The word "Equisetum" is derived from the Latin "equus," meaning "horse," and "seta," meaning "bristle."(UMMC 2017) The plant has traditionally been used as a diuretic, and in the treatment of tuberculosis,(Gruenwald 2000) genitourinary and respiratory disorders, arthritis, and bleeding ulcers.(Lininger 1998) Because of its abrasive texture (due to its high silica content), horsetail has been used to clean dishes, sand wood, and polish metal.(Weiss 1992) Externally, horsetail has been used in cosmetics(Boruch 1984) and as an astringent to stop bleeding(Schauenberg 1977) and stimulate wound healing (due to its free silica content).(Asgharikhatooni 2015, Duke 1985, Gruenwald 2000) E. myriochatum has been used in traditional medicine to treat kidney disease and type 2 diabetes.(Revilla 2002)


The stems of horsetail contain 5% to 8% silica and silicic acids. The plant contains about 5% of a saponin called equisetonin, as well as the flavone glycosides isoquercitrin, equisetrin, and galuteolin.(Tyler 1987) The sterol fraction of E. arvense contains beta-sitosterol, campesterol, isofucosterol, and trace amounts of cholesterol.(D'Agostino 1984) The alkaloid nicotine is also present in minute amounts (less than 1 ppm),(Tyler 1987) but may account for a portion of the pharmacological activity of the plant. The plant contains more than 15 types of bioflavonoids, as well as manganese, potassium, sulfur, and magnesium.(Bisset 2001, Lininger 1998) The cytokinin isopentenyladenosine has been identified in fertile fronds.(Yamane 1983)

Uses and Pharmacology

Brittle Nails

Clinical data

In 2 clinical trials evaluating a formulation of E. arvense (a plant extract rich in organic silica) and a sulfur donor in a hydroalcoholic solution (hydroxypropyl chitosan [HPCH]), improvements in nail alterations (eg, splitting, fragility, longitudinal grooves) were observed. The organic silica properties of E. arvense serve to harden and strengthen the nail, while HPCH improves nail hydration, and the sulfur donor supports nail growth.(Sparavigna 2006)


The American College of Rheumatology, for its 2012 guidelines on the management of gout, voted that the use of various oral complementary agents, including horsetail, was inappropriate for the treatment of an acute attack of gout. The new guideline (2020) based on additional evidence regarding the management of gout no longer included a statement regarding the use of horsetail.(Fitzgerald 2020, Khanna 2012)

Neuroprotective effects

In vitro and in vivo data

The neuroprotective activity of 3 Equisetum species ethanolic extracts using zebrafish tests were determined in vivo. The results indicated that E. sylvaticum extract has a significant antioxidant activity; whereas, E. pratense extract had anxiolytic and antidepressant effects significantly higher than the other 2 extracts used. Promising results for the antioxidant in vitro tests as well as the neuroprotective activity of in vivo tests for various ethanolic extracts from Equisetum species were noted.(Batir-Marin 2021)


Animal data

In a study of rats, the addition of an ethanolic extract of E. arvense to an anabolic nutrient mixture containing calcium carbonate, vitamin D, zinc sulfate, L-lysine, L-proline, L-arginine, and L-ascorbic acid was beneficial for bone formation; it was also more effective in preventing osteoporotic bone loss compared with raloxifene. Because of its high silica content, E. arvense may increase efficacy of the formulated nutrient mixture used for the treatment of osteoporosis and may aid in the prevention of osteoporosis; however, clinical trials are lacking.(Kotwal 2016)

Pancreatic carcinoma

In vitro data

In vitro testing of Equisetum arvense ethanolic extracts induced cell death in pancreatic carcinoma AsPC-1 cells.(Bhat 2020)

Urological effects

The horsetail plant exerts slight diuretic activity, possibly due to the high concentrations of flavonoids, phenolic compounds, and mineral salts found in the aerial parts of E. arvense. In addition, a review article concluded that Equisetum species have great potential in the management of kidney disorders.(Boeing 2021)

Historical reports of the use of horsetail in the treatment of urological disorders such as cystitis and urinary tract infections exist. Although horsetail shows some promise for the treatment of overactive bladder, there are no clinical data demonstrating this efficacy.(Chughtai 2013)

Clinical data

In a randomized, double-blind trial of 36 healthy male volunteers, diuretic effects comparable with those of hydrochlorothiazide 25 mg and superior to placebo were observed with E. arvense 900 mg/day. No changes in electrolytes or liver, kidney, or hematological function tests were observed, and adverse reactions were mild and infrequent. E. arvense was deemed safe for oral acute use.(Carneiro 2014)

Wound Healing

Clinical data

In a clinical trial of postpartum mothers, an E. arvense 3% ointment improved wound healing and pain intensity following episiotomy, based on reductions in scores on the Redness, Edema, Ecchymosis, Discharge and Approximation of the Edges (REEDA) scale.(Asgharikhatooni 2015)

In terms of innovative dressing materials, chitosan-based hydrogels that have been modified with E. arvense L. extracts have demonstrated beneficial effects.(Głab 2021)


E. palustre products are contraindicated for use in humans.

Brittle nails: A formulation containing E. arvense and a sulfur donor in an HPCH solution applied topically every night for 28 days in one trial, or every other day (preferably in the evening) for 14 days in another trial to strengthen fingernails.(Sparavigna 2006)

Diuretic: A dry extract of the aerial parts of E. arvense containing 0.026% total flavonoids was administered as 300 mg orally 3 times daily for 4 days (total daily dose of 900 mg, the maximum recommended dose for dry extracts) in a clinical trial of healthy volunteers.(Carneiro 2014)

Type 2 diabetes: A water extract of another species of horsetail (E. myriochaetum) as a single oral dose of 0.33 g/kg was used in a clinical study evaluating the hypoglycemic effects of horsetail.(Revilla 2002)

Wound healing: An E. arvense 3% ointment applied topically every 12 hours for 10 days was used following episiotomy in postpartum mothers.(Asgharikhatooni 2015)

Pregnancy / Lactation

Avoid use. Information regarding safety and efficacy in pregnancy and lactation is lacking.Revilla 2002


Efavirenz: Horsetail may diminish the therapeutic effect of efavirenz. Monitor therapy.(Cordova 2017)

Adverse Reactions

Research reveals limited information regarding adverse reactions with the use of horsetail; however, there was an isolated report of strong headache in 1 clinical trial from the use of a dry extract from the aerial parts of E. arvense.(Carneiro 2014) In another isolated report, a possible link between habitual consumption of horsetail infusions and recurrent episodes of acute pancreatitis were documented after all other etiologies were ruled out.(García-Gavilán 2017) A case of hyponatremia attributed to decreased oral intake and syndrome of inappropriate secretion of anti­diuretic hormone (due to nausea) possibly exacer­bated by the diuretic effect of horsetail (E. arvense) has been reported.(Bates 2021)

Individuals allergic to nicotine should avoid horsetail because of its nicotine content; one case of dermatitis has been reported.(Sudan 1985)


Horsetail has been listed as an herb of undefined safety by the FDA.(Fetrow 2000) Horsetail remedies prepared from E. arvense are generally considered safe when used properly. However, another species of horsetail, such as E. palustre, is poisonous to horses and contraindicated for use in humans.(UMMC 2017) Few in vivo toxicity studies have been conducted for most Equisetum species, so there is no consensus on an effective non-toxic dosage.(Boeing 2021)

Ingestion of large amounts of E. arvense fern may be toxic. There have been reports of children being poisoned by using the stems as blowguns or whistles.(Leung 1996) Crude horsetail contains the enzyme thiaminase, which destroys the B vitamin thiamine. Thiaminase poisoning may lead to permanent liver damage; preclinical studies have revealed various pharmacological actions of E. arvense, but no acute hepatotoxicity.(Carneiro 2014, Hallowell 1994) The Canadian Health Protection Branch prohibits thiaminase in dietary supplements, and supplement manufacturers must provide supportive documentation of its removal.(Lininger 1998) In a case report, a 52-year-old man who had consumed horsetail juice (500 mL/day for 2 weeks) and who had osteoarthritis, renal colic, and asymptomatic underlying chronic liver disease secondary to hepatitis B infection developed acute hepatitis; symptoms developed after consuming the juice for 1 week.(Klncalp 2012) In a clinical trial of healthy volunteers, oral use of E. arvense at 900 mg daily (in 3 divided doses) produced no signs of liver, kidney, hematological, or electrolyte toxicity.(Carneiro 2014)

In animals, ingestion of horsetail produces muscle weakness, ataxia, weight loss, abnormal pulse rate, cold extremities, and fever,(Klncalp 2012) symptoms similar to those occurring with nicotine intoxication. Hay composed of 20% or more of E. arvense produced these symptoms in 2 to 5 weeks.(Duke 1985) E. arvense may also induce seborrheic dermatitis in animals.(Kamphues 1990, Sudan 1985)

E. palustre contains toxic alkaloids(Bisset 2001, Lininger 1998). Cattle appear to recognize the odor of this species of horsetail and refuse to eat hay contaminated with E. palustre at a concentration of about 12%.(Spoerke 1980)

Index Terms

  • Equisetum palustre



This information relates to an herbal, vitamin, mineral or other dietary supplement. This product has not been reviewed by the FDA to determine whether it is safe or effective and is not subject to the quality standards and safety information collection standards that are applicable to most prescription drugs. This information should not be used to decide whether or not to take this product. This information does not endorse this product as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this product. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this product. This information is not specific medical advice and does not replace information you receive from your health care provider. You should talk with your health care provider for complete information about the risks and benefits of using this product.

This product may adversely interact with certain health and medical conditions, other prescription and over-the-counter drugs, foods, or other dietary supplements. This product may be unsafe when used before surgery or other medical procedures. It is important to fully inform your doctor about the herbal, vitamins, mineral or any other supplements you are taking before any kind of surgery or medical procedure. With the exception of certain products that are generally recognized as safe in normal quantities, including use of folic acid and prenatal vitamins during pregnancy, this product has not been sufficiently studied to determine whether it is safe to use during pregnancy or nursing or by persons younger than 2 years of age.

More about horsetail

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Asgharikhatooni A, Bani S, Hasanpoor S, Mohammad Alizade S, Javadzadeh Y. The effect of Equisetum arvense (horse tail) ointment on wound healing and pain intensity after episiotomy: a randomized placebo-controlled trial. Iran Red Crescent Med J. 2015;17(3):e25637.26019907
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(4):386-389. doi:10.4212/cjhp.v74i4.320234602627
Batir-Marin D, Boev M, Cioanca O, et al. Neuroprotective and antioxidant enhancing properties of selective Equisetum extracts. Molecules. 2021;26(9):2565. doi:10.3390/molecules2609256533924900
Bhat AA, Ahamad B, Rehman MU, Ahmad P. Impact of ethanolic extract of Equisetum arvense (EA1) on pancreatic carcinoma AsPC-1 cells. Saudi J Biol Sci. 2020;27(5):1260-1264. doi:10.1016/j.sjbs.2020.01.02932346333
Bisset N. Herbal Drugs and Phytopharmaceuticals. Boca Raton, FL: CRC Press; 2001.
Boeing T, Tafarelo Moreno KG, Gasparotto Junior A, Mota da Silva L, de Souza P. Phytochemistry and Pharmacology of the Genus Equisetum (Equisetaceae): A Narrative Review of the Species with Therapeutic Potential for Kidney Diseases. Evid Based Complement Alternat Med. 2021 Mar 5;2021:6658434. doi:10.1155/2021/665843433747109
Boruch T, Gora J, Kurowska A, Kalemba D, Swiatek L, Luczak S. Extracts of plants and their cosmetic application, Part V. Extracts from Equisetum arvense. Chem Abstracts. 1984;100.
Carneiro DM, Freire RC, Honório TC, et al. 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;2014:760683.24723963
Chevalier A. The Encyclopedia of Medicinal Plants. New York, NY: DK Publishing; 1996.
Chughtai B, Kavaler E, Lee R, Te A, Kaplan SA, Lowe F. Use of herbal supplements for overactive bladder. Rev Urol. 2013;15(3):93-96.24223020
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(1):11-13.27903949
D'Agostino M, Dini A, Pizza C, Senatore F, Aquino R. Sterols from Equisetum arvense. Boll Soc Ital Biol Sper. 1984;60(12):2241-2245.6529502
Duke JA. Handbook of Medicinal Herbs. Boca Raton, FL: CRC Press; 1985.
Fetrow CW, Avila JR. The Complete Guide to Herbal Medicines. New York, NY: Pocket Books; 2000.
FitzGerald JD, Dalbeth N, Mikuls T, et al. 2020 American College of Rheumatology guideline for the management of gout [published correction appears in Arthritis Care Res (Hoboken). 2020;72(8):1187] [published correction appears in Arthritis Care Res (Hoboken). 2021;73(3):458]. Arthritis Care Res (Hoboken). 2020;72(6):744-760. doi:10.1002/acr.2418032391934
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;109(4):301-304.28112963
Głąb M, Drabczyk A, Kudłacik-Kramarczyk S, Krzan M, Tyliszczak B. Physicochemical characteristics of chitosan-based hydrogels modified with Equisetum arvense L. (horsetail) extract in view of their usefulness as innovative dressing materials. Materials (Basel). 2021;14(24):7533. doi:10.3390/ma1424753334947127
Gruenwald J, Brendler T, Jaenicke C, et al. PDR for Herbal Medicines. Physician's Desk Reference (PDR). 2000:409-410.
Hallowell M. Herbal Healing: A Practical Introduction to Medicinal Herbs. Garden City Park, NY: Avery Publishing Group; 1994.
Horsetail. University of Maryland Medical Center website. Updated January 2, 2015. Accessed May 5, 2017.
Kamphues J. Refusal of breeding bulls to eat hay contaminated with horsetail (Equisetum palustre) [in German]. Tierarztl Prax. 1990;18(4):349-351.2219104
Khanna D, Khanna PP, Fitzgerald JD, et al; American College of Rheumatology. 2012 American College of Rheumatology guidelines for management of gout. Part 2: therapy and antiinflammatory prophylaxis of acute gouty arthritis. Arthritis Care Res (Hoboken). 2012;64(10):1447-1461.23024029
Klnçalp S, Ekiz F, Başar Ö, Coban S, Yüksel O. Equisetum arvense (Field horsetail)-induced liver injury. Eur J Gastroenterol Hepatol. 2012;24(2):213-214.22228296
Kotwal SD, Badole SR. Anabolic therapy with Equisetum arvense along with bone mineralising nutrients in ovariectomized rat model of osteoporosis. Indian J Pharmacol. 2016;48(3):312-315.27298503
Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs, and Cosmetics. 2nd ed. New York, NY: J Wiley; 1996.
Lininger S, Wright J, Austin S, Brown D, Gaby A. The Natural Pharmacy. Rocklin, CA: Prima Publishing; 1998.
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(1):117-120.12020935
Schauenberg P, Paris F. Guide to Medicinal Plants. New Canaan, CT: Keats Publishing; 1977.
Sparavigna A, Setaro M, Genet M, Frisenda, L. Equisetum arvense in a new transungual technology improves nail structure and appearance. J Plast Surg. 2006:2:1:31-38.
Spoerke DG. Herbal Medications. Santa Barbara, CA: Woodbridge Press; 1980.
Sudan BJ. Seborrhoeic dermatitis induced by nicotine of horsetails (Equisetum arvense L.). Contact Dermatitis. 1985;13(3):201-202.2932297
Tyler VE. The New Honest Herbal: A Sensible Guide to the Use of Herbs and Related Remedies. 2nd ed. Philadelphia, PA: GF Stickley Co; 1987.
Weiss G, Weiss S. Growing and Using the Healing Herbs. Avenel, NJ: Random House Publishing Inc; 1992.
Yamane H, Watanabe M, Satoh Y, Takahashi N, Iwatsuki K. Identification of cytokinins in two species of pteridophyte sporophytes. Plant Cell Physiol. 1983;24:1027.

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