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 Drugs.com. Last updated on Aug 22, 2019.
Horsetail has traditionally been used as a diuretic, as an astringent to stop bleeding and stimulate healing of wounds and burns, and as a cosmetic component, as well as for treatment of tuberculosis and of kidney and bladder ailments (eg, urethritis, cystitis with hematuria); however, clinical trials are lacking to support these uses. Clinical data demonstrate a hypoglycemic effect with 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; contraindicated for use in humans.
Avoid use. Information regarding safety and efficacy in pregnancy and lactation is lacking.
None well documented.
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; 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.
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, GU 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 cosmeticsBoruch 1984 and as an astringent to stop bleedingSchauenberg 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 present in minute amounts (less than 1 ppm),Tyler 1987 but may account for a portion of the pharmacologic 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
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; HPCH improves nail hydration; and the sulfur donor supports nail growth.Sparavigna 2006
The horsetail plant exerts slight diuretic activity, possibly due to the high concentrations of flavonoids, phenolic compounds, and mineral salts in the aerial parts of E. arvense.
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
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.Khanna 2012
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 treatment of osteoporosis and may aid in the prevention of osteoporosis; however, clinical trials are necessary.Kotwal 2016
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
Historical reports of the use of horsetail in the treatment of urological disorders such as cystitis and urinary tract infections exist. In folk medicine, use of E. arvense for treatment of tuberculosis has been reported.Gruenwald 2000 Although horsetail shows some promise for the treatment of overactive bladder, there are no clinical data demonstrating efficacy.Chughtai 2013
E. palustre products are contraindicated for use in humans.
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 was used to strengthen fingernails.Sparavigna 2006
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
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
Although documentation is limited, there are 2 reported instances of possible drug interactions between horsetail and certain antiretroviral drugs (ie, efavirenz, emtricitabine, tenofovir). Two patients on regimens including these medications displayed detectable viral loads after initiation of horsetail. Upon discontinuation of horsetail, viral loads resuppressed in both cases.Somerville 1997
Research reveals little or no information regarding adverse reactions with the use of horsetail; however, there was an isolated report of strong headache in one clinical trial of a dry extract of 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 was documented after all other etiologies were ruled out.García-Gavilán 2017
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, E. palustre, is poisonous to horses; contraindicated for use in humans.UMMC 2017
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 alkaloidsBisset 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
- Equisetum palustre
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