What Is It?
Health Benefits

Dosage Information

Guidelines for Use

General Interaction

Possible Side Effects

Evidence Based Rating Scale


What Is It?

Dinosaurs were still roaming the earth when this perennial flowerless plant (Equisetum arvense) first made its appearance. The numerous common names it has collected over the centuries--horsetail, bottlebrush, corncob plant, shavetail grass--refer to the distinctive brownish cones that emerge from its bamboo-like stems. It is primarily these hollow, jointed stems that are used for medicinal purposes.

Healers in centuries past considered the plant valuable for controlling bleeding from lung lesions caused by tuberculosis. Interestingly, studies in animals indicate that it also helps to stanch bleeding when applied directly to a wound.

Today, the most notable use for horsetail is as a mild Diuretic, ''water pill'', to increase urination and decrease swelling, and as a remedy for various bladder and kidney problems (including kidney stones and bladder infections). While available scientific evidence is limited, Germany's Commission E has approved horsetail as an effective treatment for these uses. (1)

Health Benefits

Scientists have identified compounds in horsetail that promote fluid loss (equisetonin and flavone glycosides). Anti-inflammatory qualities have spurred its use for inflammatory gastrointestinal conditions such as Crohn's disease. Claims that horsetail can promote weight loss (beyond simple water loss) are unfounded, however.

As a rich and natural source of easy-to-absorb silica, horsetail is likely to be effective in strengthening nails, hair, and teeth; the body requires silica to keep such connective tissue and joint Cartilage healthy and strong. In fact, it's the presence of silica that accounts for the Herb's use for the prevention of osteoporosis ("thinning bones"), to treat bursitis and tendonitis, and to enrich "natural" formulas for baldness.

Specifically, horsetail may help to:

Ease urinary tract inflammation. The diuretic properties of horsetail have been shown to be as effective as some conventional medications in increasing urination and reducing swelling in the urinary tracts of mice. (2) In humans, a 1996 study with 25 healthy volunteers given a daily dose of horsetail infusion (10.7 mg/kg of body weight) showed mild diuretic activity with no adverse reactions. (3) However, a 2007 study in mice found that a mixture composed of birch leaves, hawthorn berries, strawberry leaves, corn silk, chamomile flowers and horsetail produced a 47% greater diuretic effect in mice than horsetail taken alone. (4) While these effects may help to prevent the formation of kidney stones or bladder infections - by flushing out the urinary tract, a 2007 review of studies evaluating the use of extracts promoted as diuretics, such as horsetail, found that little reliable scientific evidence is available to confirm the traditional use of such herbs. (5)

Other studies evaluating horsetail have shown benefits, such as disinfectant and solvent actions, that may be helpful in preventing and treating kidney stone formation. However, a 1994 review found that these benefits are mild and less effective than more well-known and well-studied substances. (6) In a 1999 study of 11 patients with a history of uric acid kidney stones, horsetail supplementation did not increase urine output. (7)

Treat osteoporosis. Horsetail is rich in silica, a mineral that helps to promote the body's absorption of calcium, repair tissue, and aid in the formation of bone and cartilage. For this reason, horsetail has long been suggested as a treatment for osteoporosis (thinning bone). (8-10) However, only one study has examined horsetail for osteoporosis. In a 1999 study of 122 Italian women with osteoporosis, taking 270 mg of Osteosil, a horsetail-calcium combination used in Italy for osteoporosis and fractures, twice daily for 80 days led to significant improvements in bone density compared to those taking a placebo or not receiving treatment. After a year of continued treatment and follow-up, the groups taking horsetail or the combination product showed an average recovery of bone mass of about 2.3%. (11) More research is needed.

Speed wound healing. Horsetail has a long history of use in, stopping bleeding, treating ulcers, and promoting the healing of wounds. The high silica content of horsetail makes it useful in repairing cartilage and promoting wound healing, while its blood clotting effects help to stop bleeding. (8, 12) In a 2003 study, Mepentol, a topical ointment containing horsetail and St. John's wort extracts, was studied in three groups: healthy volunteers,  patients at risk of developing pressure ulcers (bedsores), and patients who had already developed stage I pressure ulcers. Capillary blood flow measurements indicated that the ointment led to improved local circulation in areas at risk of developing pressure ulcers as well as in stage I lesions, supporting its use in preventing pressure ulcers and treating stage I lesions. (13) More research is needed.

Strengthen hair and nails. Herbalists recommend silica for producing healthy hair and nails. The high silica content of horsetail may help to strengthen brittle hair and fingernails. (8) While few clinical trials have examined this use, a preliminary study in 2009 tested a nail lacquer containing horsetail extract on 30 adult patients with mild to moderate nail psoriasis. Applying the nail lacquer once daily on affected nails for 24 weeks led to a 72% reduction in pitting, 66% reduction in discoloration, 63% reduction in onycholysis (separation of the nail from the underlying tissue), and a 65% reduction in the Nail Psoriasis Severity Index scores compared to baseline. No changes were observed in untreated nails. (14) More research is needed.


  • Capsules (including freeze dried whole herbs)
  • Dried herb
  • Liquid extracts
  • Tablets
  • Tea

Dosage Information

--No typical dosage has been established for horsetail. However, commercial preparations typically recommend the following amounts:

  • Standardized dose: 300 mg, three times daily, standardized to contain 10 - 15% silica, 3% blackish rhizome fragments and no more than 5% stems or branches from other horsetail species.

  • Tincture (1:5): 1 - 4 ml, three times daily.

  • External (compresses): 10 g of herb per 1 liter water daily

Guidelines for Use

To prepare horsetail tea, steep 1 tablespoon of dried herb in 1 cup (8 ounces) of hot (not boiling) water: adding a little sugar reportedly releases more silica from the leaves. To use the liquid Extract, add 1/2 teaspoon to a glass of water; drink three times a day. To use the freeze-dried whole herb capsule (it's quite potent in this form), take one capsule standardized to 300 mg of horsetail three times daily.

General Interaction

Because of its mild diuretic effect, avoid taking horsetail along with any of the more potent prescription diuretic medications. Doing this could cause excessive fluid loss and an electrolyte imbalance.

Taking horsetail has been shown to have mild hypoglycemic activity. Patients with diabetes should monitor glucose carefully.

Possible Side Effects

Because horsetail contains nicotine--albeit in very small amounts--it could cause problems such as nicotine allergy or toxicity in people taking nicotine replacement patches (or other formulations) for smoking cessation. 

Because horsetail contains thiaminase, which breaks down the B vitamin thiamine, prolonged consumption may lead to thiamine deficiency. Look for products free from thiaminase-like activity. 

Note: For information on interactions with specific generic drugs, see our WholeHealthMD Drug/Nutrient Interactions Chart.


  • Horsetail will promote urination, so be sure to drink plenty of water to replace the lost fluids.

  • Only take this herb in commonly recommended amounts; large doses could cause problems because of its nicotine content.

  • Anyone taking horsetail who experiences muscle weakness, a fast or irregular heartbeat, or other unexpected discomforts, should discontinue use and call a doctor. 

  • Never take horsetail to reduce the swelling associated with poor kidney or heart function; both are potentially serious conditions that require careful medical monitoring.

  • Prolonged use (greater than six months) of horsetail is discouraged due to its content of thiaminase, an enzyme that destroys the B vitamin thiamin. Do not drink alcohol regularly while taking horsetail, as the combination may also cause a decrease in thiamin levels.

  • Women who are pregnant or breastfeeding should not take horsetail.

Drug/Nutrient Interactions

Increased diuresis may cause more rapid elimination of drugs that are metabolized in the kidneys and decrease their effectiveness. Consult your physician or the package insert regarding potential interaction with any prescription medications you may be using. 


1. Blumenthal M, Goldberg A, Brinckmann J, eds. Herbal Medicine: Expanded Commission E Monographs. Newton, MA: Integrative Medicine Communications; 2000:208-211.
2. Pérez Gutiérrez RM, Laguna GY, Walkowski A. Diuretic activity of Mexican equisetum. J Ethnopharmacol. 1985 Nov-Dec;14(2-3):269-72.
3. Lemus R, Garcia S, Erazo S, et al. Diuretic activity of an Equisetum bogotense tea (Platero herb): evaluation in healthy volunteers. J Ethnopharmacol. 1996;54:55-8.
4. Masteiková R, Klimas R, Samura BB, et al. An orientational examination of the effects of extracts from mixtures of herbal drugs on selected renal functions. Ceska Slov Farm. 2007 Apr;56(2):85-9.
5. Wright CI, Van-Buren L, Kroner CI, Koning MM. Herbal medicines as diuretics: a review of the scientific evidence. J Ethnopharmacol. 2007 Oct 8;114(1):1-31.
6. Grases F, Melero G, Costa-Bauzá A, Prieto R, March JG. Urolithiasis and phytotherapy. Int Urol Nephrol. 1994;26(5):507-11.
7. Graefe EU, Veit M. Urinary metabolites of flavonoids and hydroxycinnamic acids in humans after application of a crude extract from Equisetum arvense. Phytomedicine. 1999 Oct;6(4):239-46.
8. 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.
9. Fischer-Rizzi, S. Medicine of the Earth. Rudra Press, 1996.
10. American Herb Association. Complete Book of Herbs. Illinois: Publications International, Ltd., 1997.
11. Corletto F. Female climacteric osteoporosis therapy with titrated horsetail (Equisetum arvense) extract plus calcium (osteosil calcium): randomized double blind study. Miner Ortoped Traumatol. 1999;50:201-6.
12. Sakurai N, Lizuka T, Nakayama S, et al. Vasorelaxant activity of caffeic acid derivatives from Cichorium intybus and Equisetum arvense. Yakugaku Zasshi. 2003;123:593-8.
13. Torra i Bou JE, Reuda López J, Segovia Gómez T, Bermejo Martínez M. Topical administration of an hyperoxygenated fatty acid compound. Preventive and curative effects on pressure ulcer. Rev Enferm. 2003 Jan;26(1):54-61.
14. Cantoresi F, Sorgi P, Arcese A, et al. Improvement of psoriatic onychodystrophy by a water-soluble nail lacquer. J Eur Acad Dermatol Venereol. 2009 Jul;23(7):832-4.

Evidence Based Rating Scale

The Evidence Based Rating Scale is a tool that helps consumers translate the findings of medical research studies and what our clinical advisors have found to be efficacious in their personal practice into a visual and easy to interpret format. This tool is meant to simplify the information on supplements and therapies that demonstrate promise in the treatment of certain conditions.






Cuts and scrapes


Preliminary studies have shown the high silica content and blood clotting effects may be beneficial in speeding wound healing. More research is needed. (8, 12-13)

Hair problems  

A long history of use and preliminary research indicates potential efficacy in strengthening brittle hair. (8)


Kidney stones  
Conflicting evidence exists. More research is needed. (6-7)

Nail problems  
A long history of use and preliminary research indicates efficacy in strengthening nails and improving symptoms of nail psoriasis. More research is needed. (8, 14)
Preliminary evidence indicates efficacy in improving bone density when combined with calcium in a specific product. More research is needed to confirm these initial results. (8-11)


Date Published: 04/18/2005
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