Horsetail (Equisetum arvense) Be aware that the U.S. Food and Drug Administration does not strictly regulate herbs and dietary supplements. There is no guarantee of strength, purity or safety of products containing or claiming to contain horsetail. Decisions to use herbs or supplements should be carefully considered. Individuals using prescription drugs should discuss taking herbs or supplements with a pharmacist or health care professional before starting.
Scientists have studied horsetail for the following health problems: Diuresis | Horsetail products have been observed to have diuretic effects (that is, they increase the production of urine). There is only limited research in humans specifically using horsetail. However, because there is a scientific basis for horsetail working as a diuretic, this evidence combined with the available limited research suggests that horsetail likely does increase urine. It is not clear what dose is safe or effective. | Osteoporosis | One study suggests that horsetail may increase the rate of bone formation and aid in calcium deposition into bone. However, this study is small, with flaws in its design. Therefore, it is unclear whether there is any benefit from horsetail for osteoporosis. |
Horsetail has been suggested for many other uses, based on tradition or on scientific theories. However, these uses have not been thoroughly studied in humans, and there is limited scientific evidence about safety or effectiveness. Some of these suggested uses are for conditions that are potentially very serious and even life-threatening. You should consult with a health care professional before taking horsetail for any unproven use. Antibacterial
Antioxidant
Astringent
Bed-wetting
Bladder disorders
Bleeding
Blood in the urine
Brittle fingernails
Cancer
Cosmetic uses
Cystic ulcers
Diabetes
Edema
Excessive blood loss with menstruation
Fever
Frostbite
Gonorrhea
Gout
Hair loss | Hepatitis
Incontinence
Kidney disease
Kidney stones
Liver protection
Malaria
Nosebleeds
Prostate inflammation
Reiter's syndrome
Rheumatoid arthritis
Sedative
Seizures
Skin disease
Stomach upset
Thyroid disease
Tuberculosis
Urinary tract infection
Urinary tract inflammation
Vaginal discharge
Wound healing |
Allergies People should avoid horsetail if they have a known allergy to horsetail or sensitivity to nicotine. Signs of allergy include rash, itching or shortness of breath. Side Effects Horsetail has been well tolerated in studies. Some people experience stomach discomfort or nausea and more frequent stools. Nerve damage has occurred. Symptoms may include confusion, difficulty walking, visual disturbances or amnesia (loss of memory). These symptoms are believed to occur because horsetail lowers the levels of vitamin B1 (thiamine) in the body. Skin irritation may occur and may be caused by horsetail allergies. Horsetail may also cause low potassium levels or low blood sugar. Another possible side effect may be muscle weakness, but this has not been studied in humans. Be aware that many tinctures contain high levels of alcohol and should be avoided when driving or operating heavy machinery. Pregnancy And Breast-Feeding Horsetail cannot be recommended during pregnancy or breast-feeding because of the risks associated with vitamin B1 (thiamine) deficiency, low blood potassium levels and nicotine toxicity. Be aware that many tinctures contain high levels of alcohol and should be avoided during pregnancy.
Interactions with drugs, supplements and other herbs have not been thoroughly studied. The interactions listed below have been reported in scientific publications. If you are taking prescription drugs, speak with a health care professional or pharmacist before using herbs or dietary supplements. Interactions With Drugs Nicotine, a stimulant, may be found in horsetail. If horsetail is taken with cigarettes, nicotine replacement therapy or other stimulant drugs, fever, rapid heartbeats, difficulty walking, muscle weakness or weight loss may occur. In theory, taking horsetail with diuretics (such as hydrochlorothiazide), corticosteroids (such as prednisone) or laxatives may cause potassium levels in the blood to be too low or may lead to dehydration. Low potassium levels may increase the toxicity of heart drugs, such as digoxin (Lanoxin). Monitoring of blood potassium levels by a health care professional is recommended. Chronic alcohol abusers may be at risk of nerve damage associated with horsetail, as a result of reduced levels of vitamin B1 (thiamine) in the body. Other horsetail species have caused low blood sugar. Be aware that many tinctures contain high levels of alcohol and may cause nausea or vomiting when taken with metronidazole (Flagyl) or disulfiram (Antabuse). Interactions With Herbs And Dietary Supplements Horsetail may lower potassium levels in the blood. It should be used carefully with licorice, herbs with laxative properties (such as senna) and herbs with diuretic properties because potassium levels may fall too low. Because of the tendency for horsetail to lower potassium levels, there may be an increased risk of toxic effects if taken with herbal supplements that affect the heart, such as foxglove or oleander. Monitoring of blood potassium levels by a qualified health care professional is recommended. Horsetail may include nicotine, and there may be increased adverse effects, such as rapid heartbeats, if horsetail is taken with other stimulants, such as ephedra. Other horsetail species have caused low blood sugar.
The doses listed below are based on scientific research, publications or traditional use. Because most herbs and supplements have not been thoroughly studied or monitored, safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients even within the same brand. Combination products often contain small amounts of each ingredient and may not be effective. Appropriate dosing should be discussed with a health care professional before starting therapy; always read the recommendations on a product's label. The dosing for unproven uses should be approached cautiously, because scientific information is limited in these areas. There are no standard or well-studied doses of horsetail, and many different doses are used traditionally. Adults (Aged 18 Or Older) Tablets/capsules: A dose of 300 milligrams taken by mouth three times daily initially, up to a maximum of six grams daily, has been used. Tea: A dose of 1.5 grams of dried horsetail stem in one cup of hot water (drinking up to six cups of tea daily, when needed) has been used. Tincture: A tincture (1:1 in 25 percent alcohol) of one to four milliliters taken by mouth three times daily has been used. Children (Younger Than 18) There are not enough scientific data to recommend horsetail for use in children, and this herb is not recommended because of potential side effects. Poisoning has occurred in children using horsetail stems as whistles.
Horsetail has been suggested as a treatment for many conditions. There is some research to support the use of horsetail as a diuretic, although it is not clear what dose is safe and effective. There is not enough scientific evidence to support the use of horsetail for any other medical condition. Horsetail may lower potassium levels in the blood and should be used carefully by people taking drugs that increase the risk of low potassium or increase the tendency for toxic effects associated with low potassium. Other horsetail species have caused low blood sugar. It should be avoided in pregnant or breast-feeding women and in children. Consult a health care professional immediately if you have any side effects. The information in this monograph was prepared by the professional staff at Natural Standard, based on thorough systematic review of scientific evidence. The material was reviewed by the Faculty of the Harvard Medical School with final editing approved by Natural Standard.
- Natural Standard: An organization that produces scientifically based reviews of complementary and alternative medicine (CAM) topics
- National Center for Complementary and Alternative Medicine (NCCAM): A division of the U.S. Department of Health & Human Services dedicated to research
Selected Scientific Studies: Horsetail Natural Standard reviewed more than 55 articles to prepare the professional monograph from which this version was created. Some of the more recent studies are listed below: - Dos Santos JG Jr, Blanco MM, Do Monte FH, et al. Sedative and anticonvulsant effects oh hydroalcoholic extract of Equisetum arvense. Fitoterapia 2005;Jun 20. [Epub ahead of print.]
- Fabre B, Geay B, Beaufils P. Thiaminase activity in Equisetum arvense and its extracts. Plant Med Phytother 1993;26:190-197.
- 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):239-246.
- Joksic G, Stankovic M, Novak A. Antibacterial medicinal plants Equiseti herba and Ononidis radix modulate micronucleus formation in human lymphocytes in vitro. J Environ Pathol Toxicol Oncol 2003;22(1):41-48.
- Maeda H, Miyamoto K, Sano T. Occurrence of dermatitis in rats fed a cholesterol diet containing field horsetail (Equisetum arvense L.). J Nutr Sci Vitaminol (Tokyo) 1997;Oct, 43(5):553-563.
- 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;Dec, 95(2-3):421-424.
- Revilla MC, Andrade-Cetto A, Islas S, Wiedenfeld H. Hypoglycemic effect of Equisetum myriochaetum aerial parts on type 2 diabetic patients. J Ethnopharmacol 2002;Jun, 81(1):117-120.
- Sudan BJ. Seborrhoeic dermatitis induced by nicotine of horsetails (Equisetum arvense L.). Contact Derm 1985;13(3):201-202.
Last updated June 29, 2005
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