Horsetail (Equisetum arvense L.)

 
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Horsetail
Horsetail

Background

Horsetail ( Equisetum arvense ) has traditionally been used in Europe as a diuretic for the treatment of edema (swelling/fluid retention). The German Commission E expert panel has approved horsetail for this indication. Horsetail is also occasionally used for osteoporosis, nephrolithiasis, urinary tract inflammation, and wound healing (topical). These uses have largely been based on anecdote and clinical tradition, rather than scientific evidence.

 

There is preliminary human evidence supporting the use of horsetail as a diuretic. One poorly designed human trial found horsetail to effectively raise bone density equally to calcium supplements.

 

In theory (based on mechanism of action), horsetail ingestion in large amounts may cause thiamine deficiency, hypokalemia, or nicotine toxicity. Reported adverse effects include dermatitis.

 

Synonyms

Bottle brush, cola de caballo, common horsetail, common scouring rush, corncob plant, corn horsetail, Dutch rush, field horsetail, horse willow, horsetail grass, horsetail rush, mokuzoku, mokchok, muzei ( E. hymale ), paddock pipes, pewterwort, prele, pribes des champs, running clubmoss, Schachtelhalm, scouring rush, shave grass, Shenjincao, toadpipe, Wenjing, Zinnkraut.

 

Crude drugs derived from  Equisetum arvense  include Wenjing, Jiejiecao, and Bitoucai.

 

Note:  Equisetum arvense  should not be confused with members of the genus Laminaria ,  kelp, or brown alga, for which "horsetail" has been used as a synonym.

 

Evidence

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Uses based on scientific evidence Grade*
Diuresis (increased urine)

Use of horsetail dates to ancient Roman and Greek medicine. The name Equisetum is derived from equus, "horse" and seta, "bristle." Preliminary human and laboratory research suggests that horsetail may increase the amount of urine produced by the body. More studies are needed to determine if horsetail is safe or useful for specific health conditions.

B
Osteoporosis (weakening of the bones)

Silicon may be beneficial for bone strengthening. Because horsetail contains silicon, it has been suggested as a possible natural treatment for osteoporosis. Preliminary human study reports benefits, but more detailed research is needed before a firm recommendation can be made. People with osteoporosis should speak with a qualified healthcare provider about possible treatment with more proven therapies.

C

 

*Key to grades
A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
D: Fair scientific evidence against this use;
F: Strong scientific evidence against this use.

 

Grading rationale

Uses based on tradition or theory
The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Antioxidant, antibacterial, antioxidant, astringent, bladder disturbances, bleeding, brittle fingernails, cancer, cosmetics, cystic ulcers, diabetes, dropsy, fever, fluid in the lungs, frostbite, gonorrhea, gout, hair loss, hepatitis, itch, kidney disease, kidney stones, leg swelling, liver protection, malaria, menstrual pain, nosebleeds, prostate inflammation, styptic (to stop bleeding cuts on the skin), Reiter's syndrome, rheumatism, stomach upset, thyroid disorders, tuberculosis, urinary incontinence, urinary tract infection (UTI), urinary tract inflammation, wound healing.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)
Recommended doses for horsetail are based on historical use or expert opinion. There are no reliable studies available in humans that show horsetail to be effective or safe at any specific dose.

 

By Mouth:
Tablets/Capsules: Different doses have been used, starting at 300-milligram capsules taken three times per day, up to 6 grams per day.

 

Tea: A maximum of 6 cups of tea, containing 1.5 grams of dried stem in one cup of hot water, is a dose that has been used.

 

Tincture (1:1 in 25% alcohol): 1 to 4 milliliters three times daily has been used.

 

Applied to the skin:
External wash: A wash prepared by mixing 10 teaspoons of horsetail in cold water and soaking for 10 to 12 hours has been used.

 

Children (younger than 18 years)
There is not enough scientific information to recommend the use of horsetail in children. Poisonings have been reported in children using horsetail stems as whistles.

 

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies
People with allergies to  E. arvense,  related substances, or to nicotine should avoid horsetail. Rash has been reported in a patient taking horsetail who was known to be sensitive to nicotine.

 

Side Effects and Warnings
There are few scientific studies or reports of side effects with horsetail. It is more often used in Germany and Canada, where it is traditionally considered to be safe when taken in appropriate doses.  E. palustre  (marsh horsetail) contains a poisonous ingredient and should be avoided. There are reports that some batches of  E. arvense  (horsetail) have been contaminated with  E. palustre .

 

Large doses of horsetail may cause symptoms of nicotine overdose, including fever, cold hands and feet, abnormal heart rate, difficulty walking, muscle weakness, and weight loss. People who smoke or who use nicotine patches or nicotine gum should avoid horsetail. Reports from animal studies and one report of a nicotine-allergic person describe a rash occurring after the use of white horsetail. Other reports from use in animals describe nausea, increased frequency of bowel movements, increased urination, loss of the body's potassium stores, and muscle weakness. People with kidney disorders should avoid horsetail.

 

Studies in mice suggest that horsetail may change the activity of the kidneys, causing abnormal control of the amount of water and potassium release. Low potassium, which in theory may occur with horsetail, can have negative effects on the heart. Individuals who have heart rhythm disorders or who take digoxin should be cautious. Studies suggest that horsetail does not change blood pressure. Other horsetail species have caused low blood sugar.

 

Horsetail contains an ingredient that destroys thiamine (vitamin B1), which could lead to deficiency with long-term use. This may cause permanent damage to the brain and nervous system, including confusion, difficulty walking, difficulties with vision and eye movement, and memory loss. People who have thiamine (vitamin B1) deficiency or poor nutrition should avoid horsetail, as it may affect levels of thiamine even more. Alcoholic or malnourished individuals are often thiamine deficient and this may be worsened by horsetail.

 

Avoid use in children due to anecdotal reports of poisonings while using horsetail stems as whistles.

 

Pregnancy and Breastfeeding
Horsetail is not recommended during pregnancy or breastfeeding, since little information is available about its safety. Its potential to cause thiamine (vitamin B1) depletion, low potassium, and nicotine-like effects are of particular concern. Many tinctures contain high levels of alcohol, and should be avoided during pregnancy.

 

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs
Some diuretic drugs ("water pills") can cause the body to lose water and potassium, for example loop diuretics like furosemide (Lasix®). The use of horsetail with certain diuretics may cause dehydration or further potassium deficiency. Some steroids and laxative drugs can also lower potassium levels and should not be combined with horsetail. Individuals with heart rhythm disorders who are treated with (Lanoxin®) or digitoxin may be especially sensitive to low potassium levels, and potassium levels should be monitored in such individuals. Because horsetail can stimulate the brain and nervous system, caution should be used when combining horsetail with stimulant drugs and nicotine. Other horsetail species have caused low blood sugar and therefore may increase effects of diabetes medications.

 

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
Increased urine production, dehydration, or electrolyte imbalances may theoretically occur when horsetail is used with herbs that may increase urination. Dehydration or low potassium levels also may theoretically occur if horsetail is used with laxatives.

 

In theory, low potassium levels caused by horsetail may be dangerous in people using herbs that have cardiac glycoside activity on the heart such as oleander.

 

Horsetail may break down thiamin and may cause thiamine deficiency. Other horsetail species have caused low blood sugar and therefore may increase effects of herbs and supplements that also lower blood sugar levels. Horsetail may interact with stimulants and herbs and supplements with similar properties such as licorice.