Horsetail (Equisetum arvense), an herbal remedy dating back to at least ancient Roman and Greek medicine, was used traditionally to stop bleeding, heal ulcers and wounds, and treat tuberculosis and kidney problems. The name Equisetum is derived from the Latin roots equus, meaning "horse" and seta, meaning "bristle."

Today, horsetail continues to have medicinal value. The plant's stems are rich in silica and silicic acids, which help mend broken bones and form collagen, an important protein found in connective tissue, skin, bone, cartilage, and ligaments. Horsetail is also used to treat infections of the urinary tract, kidney and bladder stones, and as topical therapy for burns and wounds.

Horsetail is a descendent of huge, tree-like plants that thrived 400 million years ago during the Paleozoic era. A close relative of the fern, horsetail is a non-flowering weed found throughout parts of Europe, Asia, the Middle East, and North America. The plant is a perennial (returns each year) with hollow stems and shoots that look like asparagus. As the plant dries, silica crystals that form in the stems and branches give the plant a scratching effect, thus accounting for its historic use in polishing metal, particularly pewter.

The aboveground parts of horsetail (fresh or dried) are used for medicinal purposes.

Horsetail has not been extensively studied people, but professional herbalists recognize that the herb has diuretic (promotes the excretion of urine) properties that may be useful for the following health problems:

• Urinary tract infections
• Kidney stones

Horsetail also can be applied externally to treat the following conditions:

• Burns (first-degree)
• Fractures
• Rheumatic conditions
• Sprains
• Wounds (especially poorly healing ones)

Horsetail is available in the following forms:

• Dried herb
• Liquid preparations

Horsetail preparations should be stored in well-sealed containers to ensure protection from light.

Adequate fluid should be consumed when taking horsetail preparations orally.

A tea is prepared by pouring boiled water over 2 to 3 g horsetail herb, boiling for five minutes, and then straining after 10 to 15 minutes. Drink during the day between meals.

An infusion for internal use is made by adding 1.5 g of horsetail herb to 1 cup of boiling water. Let it steep for 30 to 40 minutes.

Pediatric

For fractures, adjust the recommended adult dose to account for the child's weight. Most herbal dosages for adults are calculated on the basis of a 150 lb (70 kg) adult. Therefore, if the child weighs 50 lb (20 to 25 kg), the appropriate dose of horsetail for this child would be 1/3 of the adult dosage.

Adult

• Internal: 6 g per day
• Herbal infusion: 4 oz three times per day
• Tincture (1:5): 1 to 4 mL three times per day
• External (compresses): 10 g of herb per 1 L water per day

The use of herbs is a time-honored approach to strengthening the body and treating disease. Herbs, however, contain active substances that can trigger side effects and interact with other herbs, supplements, or medications. For these reasons, herbs should be taken with care, under the supervision of a practitioner knowledgeable in the field of botanical medicine.

Horsetail remedies prepared from Equisetum arvense are generally considered safe. Another species of horsetail, however, called E. palustre is poisonous to horses. Although it is not known for certain that E. palustre would have the same effect on people, it should never be ingested. Most commercial preparations of horsetail are not contaminated with E. palustre; however, be sure to buy products made by an established company with a good reputation that distributes their products through trustworthy and knowledgeable establishments. Whenever possible, select products with guaranteed potency or standardized extracts.

Prolonged use of even the safe form of horsetail (E. arvense) is also not advised.

People with heart or kidney disorders should not use horsetail.

The diuretic effects of horsetail may enhance the toxic effects of digoxin, a medication used to treat irregular heart rhythms and, sometimes, congestive heart failure. For this reason, people taking digoxin should note take horsetail without first consulting a healthcare provider.

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