Equisetaceae (Plant Family)
Horsetail belongs to Equisetum, the only genus in the family
Equisetaceae. It is a descendant of a large, primeval plant that thrived 400
million years ago during the Paleozoic geological period. The genus name,
Equisetum, comes from two Latin words which mean "bristle horse." It
bears this name because its stems are rich in silica and silicic acids. As the
plant dries, silica crystals form on the walls of cells in the stems and
branches. These crystals give the ground plant material a scratching effect. It
is for this reason that horsetail historically has been used to polish metal,
particularly pewter. Horsetail is also known as "scouring rush" and
"pewterwort," appropriate synonyms in light of these traditional uses for the
Studies on the flavonoid compounds in Equisetum arvense reveal that
this species has two discrete chemotypes, or chemical subspecies. One chemotype
is native to North America and the Far East, including China, Japan, and
Siberia, while the other is indigenous to Europe. Horsetail is now widespread
throughout parts of Europe, Asia, the Middle East, and North America.
Closely related to the ferns, horsetail is a non-flowering weed that
flourishes on clay-filled, sandy soils. It is technically a pteridophyte and, as
in the case of ferns, reproduces through spores. Pteridophytes are flowerless
plants that have two distinct and alternating generations. The first is a
non-sexual, spore-bearing generation of relatively larger plants. The second
generation is sexual, and composed of smaller plants that lack
well-differentiated stems and leaves. Equisetum species can also
propagate non-sexually through stolons and tubers.
Best known as a mild diuretic, the aerial parts of horsetail are used
medicinally for numerous ailments. The astringent properties of this plant
render it a valuable treatment for kidney and bladder complaints, as well as an
external therapy for bleeding wounds. Although horsetail is also indicated for
dropsy, rheumatic conditions, and tuberculosis, there is no pharmacological
evidence that it is effective in treating conditions other than mild water
While horsetail remedies prepared from Equisetum arvense are basically
safe, other Equisetum species such as Equisetum palustre
contain poisonous alkaloidal constituents. Every effort should thus be made to
ensure that horsetail herbal preparations are made from Equisetum arvense.
The authenticity of Equisetum arvense should be confirmed by
both morphological and chemical studies using microscopy and thin layer
Horsetail is a perennial with the two distinct forms of stems. Between March
and April, red-brown to straw-yellow fertile stems grow up to 20 cm in height.
These pencil-slim stems bear brown, scale-like leaves arranged in whorls. At the
tip of each stem is a scaly head containing a spore that is easily transported
by the wind to other plants for sexual reproduction.
By early summer, usually during May and June, longer, sterile green stems
appear that form a pale green brush up to 35 cm high. These barren stems give of
multiple branches arranged in whorls at the nodes. The sterile stems and
branches are characterized by deep grooves, a square-shape, and a rough texture.
Both the fertile and barren stems are erect, jointed, and brittle. However, only
the sterile stems are used medicinally.
Herb (fresh or dried sterile, green shoots).
Flavonoids (particularly quercetin 3-glucoside and its 6"-malonyl ester are
found in both chemotypes; also kaempferol-, luteolin-, genkwanin-3-O-glucosides;
5-0-, 7-0-glucosides; and diglucosides); caffeic acid ester (chlorogenic acid,
dicoffeoyl-meso-tartaric acid); silicic acid (partially water-soluble);
styrolpyrone glucoside (equisetumpyron); pyridine alkaloids (nicotine in trace
amounts). The purported presence of equisetonin, a saponin of unknown structure,
Available as dried herb and liquid preparations made from the fresh or dried,
green, sterile shoots of Equisetum arvense. Horsetail preparations should
be stored in well-sealed containers to ensure protection from light.
Traditional uses: tuberculosis; nasal, pulmonary, and gastric hemorrhages;
brittle fingernails and hair loss; rheumatic diseases; gout; catarrh for kidney
and bladder areas; hematostatic (a therapeutic agent that stops bleeding) for
profuse menstruation; stubborn wounds and ulcers, swelling and fracture;
- Internal: inflammation or mild infections of the genito-urinary tract,
kidney stones, bladder stones
- External: wounds, burns, poorly healing wounds, rheumatic conditions,
- Internal: post-traumatic and static edemal, flushing-out (irrigation)
treatment for bacterial and inflammatory diseases of the lower urinary tract;
- External: supportive therapy for poorly healing
Although pharmacological investigations on Equisetum arvense are
limited, this herb has been shown to have mild diuretic, hemostatic (arresting
the blood flow), and vulnerary (wound-healing) properties. In addition,
horsetail induces mild leucocytosis (a transient increase in white blood cell
In vivo studies confirm that horsetail has weak diuretic action, but research
findings have been inconsistent. Flavonoids presumably account for the diuretic
effect, which apparently does not involve an increase in electrolyte excretion.
However, other evidence suggests that the diuretic activity of horsetail results
from the combined pharmacological action of flavone glycosides and the saponin.
In other animal studies, horsetail was shown to produce a hemostatic effect.
Therapeutic claims that horsetail and its active constituents, silica and
silicic acid derivatives, promote tissue repair of bleeding pulmonary tubercular
lesions have not been fully substantiated. However, in other research, the
silicic acid content of horsetail reportedly had a strengthening and
regenerative effect on connective tissues.
|Dosage Ranges and Duration of
- Internal: 6 g per day
- Herbal infusion: 4 oz. tid
- Tincture (1:5): 1 to 4 ml tid
- External (compresses): 10 g of herb per 1 liter water per day
Adequate fluid should be taken when using oral horsetail preparations for
irrigation therapy. 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 steep 30
to 40 minutes.
Health risks and side effects have not been reported for horsetail when taken
in recommended therapeutic doses. However, it is advisable to consult a health
care practitioner when using fresh horsetail as a bath additive to treat major
skin lesions, acute skin lesions of unknown origin, feverish and infectious
diseases, or hypertonia (increased muscle resistance to passive stretching).
Horsetail is contraindicated in patients who have edema concomitant to
cardiac or renal dysfunction. A related species, Equisetum palustre, is
potentially toxic since it contains lapustrin, a poisonous alkaloid.
Although horsetail reportedly possesses diuretic properties, no clinically
significant interactions between horsetail and conventional medications are
known to have been reported in the literature to date, including the German
Commission E monograph (Blumenthal 1998).
|Regulatory and Compendial
Horsetail herb is approved by the German Commission E. In the United Kingdom,
horsetail is on the General Sale List, Schedule 2, Table A (R1a).
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Copyright © 2000 Integrative Medicine
CommunicationsThis publication contains
information relating to general principles
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