Horsetail Benefits and Side Effects
Horsetail [Equisetum arvense] has been used as an oral diuretic for relieving edema
for thousand years in Europe. It is also believed to benefit osteoporosis,
nephrolithiasis, urinary tract inflammation, and wound healing. 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. Silicon may be beneficial for bone strengthening. Because horsetail contains
silicon, it has been suggested as a possible natural treatment for osteoporosis. [X2]
Preliminary human study reports benefits, but more detailed research is needed
before a firm recommendation can be made.
Essential oil of Horsetail was shown to possess a broad spectrum of a very
strong antimicrobial activity against some bacteria and fungi.
Researchers identified Twenty-five compounds in Horsetail essential oil. The major
constituents for this essential oil include Hexahydrofarnesyl acetone (18.34%),
cis-geranyl acetone (13.74%), thymol (12.09%) and trans-phytol (10.06%).
Researchers found that Horsetail essential oil had activities against a panel of
microorganisms (bacteria: Staphylococcus aureus, Escherichia coli, Klebsiella
pneumoniae, Pseudomonas aeruginosa and Salmonella enteritidis; fungi: Aspergillus
niger and Candida albicans). 
Horsetail may benefit convulsion and insomnia, an animal study suggests.
Brazilian Researchers proposed anti-convulsion and sedative activities of horsetail
extracts, based on the results of an animal study.  In the
pentylenetetrazole-seizure, the extract increased the first convulsion latency,
diminished the severity of convulsions, reduced the percentage of animals to
develop convulsion and protected them from death. In the sedative study, they found
the extract increased the sleeping time in the barbiturate-induced sleeping of the
Horsetail may enhance cognition, Brazilian researchers suggest.
In a study of aged rats, Brazilian researchers found improved both short- and
long-term retention of inhibitory avoidance task and ameliorated the cognitive
performance after repeatedly administration of horsetail extracts to the aged
animals. In the study, they did not find any toxic manifestations. 
Horsetail shows protective benefits on liver cells in a culture study.
Korean researchers isolated a few compounds from horsetail and noticed two of
them exhibited hepatoprotective activities on tacrine-induced cytotoxicity in human
liver-derived Hep G2 cells, displaying EC(50) values of 85.8 +/ -9.3 microM and 20.2
+/- 1.4 microM. 
Horsetail may benefit kidney stone, a rat study suggests.
Researchers from University of Balearic Islands Spain concluded the that the
beneficial effects caused by horsetail infusions on urolithiasis could be attributed to
some disinfectant action, and tentatively to the presence of saponins from a study of
Wistar rats. Specifically, some solvent action can be postulated with respect to uric
stones or heterogeneous uric nucleus. 
Horsetail reduced paw edema in a mice study.
In the carrageenan-induced paw oedema, the extract at 50mgkg(-1), reduced the
paw oedema 2h (25%) and 4h (30%) after carrageenan administration. The dose of
100mgkg(-1) caused reduction of the paw oedema (29%) only 4h after carrageenan
Horsetail shows anti-platelet aggregation in a test tube study.
In the study, horsetail extracts produced a dose-dependent inhibition of thrombin
and ADP-induced aggregation. The researchers believe the effects of the plant is
related to the polyphenolic compounds present in the extracts, thus, horsetail extract
may help treat or prevent platelet aggregation complications linked to cardiovascular
Horsetail compound showed vaso-relaxation in an in vitro study.
dicaffeoyl-meso-tartaric acid from Equisetum arvense L. (horsetail) showed
vaso-relaxant activities in isolated rat aorta strips. It also showed slow relaxation
activity against norepinephrine (NE)-induced contraction of rat aorta with/without
endothelium. It also did not affect contraction induced by a high concentration of
potassium (60 mM K+), while it still inhibited NE-induced vasocontraction in the
presence of nicardipine. 
Potential Side Effects of Horsetail
Because of its native action, intake of horsetail in excessive amounts may lead to
nausea, increased frequency of bowel movements, increased urination, loss of
potassium stores, and muscle weakness. People with kidney disorders and diabetes
should avoid horsetail. People who have thiamine (vitamin B1) deficiency or poor
nutrition or are pregnant should also avoid horsetail, as it may affect levels of
thiamine. Avoid taking horsetail together with other diuretics, steroids and laxatives.
When taken in appropriate doses, it is traditionally considered to be safe. Its
adverse side effect includes skin rash, dermatitis. [X1] Uncommonly, its side effects
include brain and heart diseases.
THIS ARTICLE IS FOR YOUR REFERENCE ONLY. IF YOU HAVE ANY QUESTION, YOU SHOULD CONSULT WITH
YOUR DOCTOR. DOSAGE AND EXPERIMENT DESIGN WILL AFFECT THE RESULTS. EXTRACTS WORK IN
ANIMALS MAY NOT WORK IN HUMAN. ALL RIGHT RESERVED 2008 ZHION.
 Radulovic N, et al, Composition and antimicrobial activity of Equisetum arvense L. essential oil. Phytother
Res. 2006 Jan;20(1):85-8.  Dos Santos JG Jr, et al, Sedative and anticonvulsant effects of hydroalcoholic
extract of Equisetum arvense. Fitoterapia. 2005 Sep;76(6):508-13.  Guilherme dos Santos J Jr, et al, Cognitive
enhancement in aged rats after chronic administration of Equisetum arvense L. with demonstrated antioxidant
properties in vitro. Pharmacol Biochem Behav. 2005 Jul;81(3):593-600.  Oh H, et al, Hepatoprotective and
free radical scavenging activities of phenolic petrosins and flavonoids isolated from Equisetum arvense. J
Ethnopharmacol. 2004 Dec;95(2-3):421-4.  Mekhfi H, et al, Platelet anti-aggregant property of some Moroccan
medicinal plants. J Ethnopharmacol. 2004 Oct;94(2-3):317-22.  Grases F, et al, Urolithiasis and phytotherapy.
Int Urol Nephrol. 1994;26(5):507-11 [X1] Maeda H, Occurrence of dermatitis in rats fed a cholesterol diet
containing field horsetail (Equisetum arvense L.). J Nutr Sci Vitaminol (Tokyo). 1997 Oct;43(5):553-63. [X2]
Holzhuter G, et al, Structure of silica in Equisetum arvense. Anal Bioanal Chem. 2003 Jun;376(4):512-7. Epub
2003 May 6.  Sakurai N, et al, Vasorelaxant activity of caffeic acid derivatives from Cichorium intybus and
Equisetum arvenseYakugaku Zasshi. 2003 Jul;123(7):593-8.