Horsetail Equisetum (Equisetum arvense): Benefits, Dosage, Safety & Evidence

Frequently asked questions

How does horsetail work in the body?

Horsetail works primarily through its exceptionally high silica (silicon) content, which supports collagen formation and connective tissue strength. The herb contains flavonoids like kaempferol and quercetin that provide anti-inflammatory and diuretic effects by increasing urine output. Its astringent compounds, including equisetonin, contribute to wound healing and hemostatic properties by helping to stop bleeding. Evidence level: C and Traditional use supports these mechanisms, though clinical trials remain limited.

Does horsetail interact with any medications?

Yes, horsetail can interact with several medications. Due to its diuretic effects, it may increase the elimination of lithium, potentially reducing its effectiveness and requiring dosage adjustments. Horsetail should not be combined with other diuretic medications as this may cause excessive fluid loss and electrolyte imbalances. The herb may also interact with antidiabetic medications by affecting blood sugar levels. Patients taking these medications should consult a healthcare provider before using horsetail supplements. Evidence level: C.

What is the recommended dosage for horsetail?

The typical adult dosage for horsetail is 6 grams of dried herb prepared as a tea, taken daily. Alternatively, standardized extracts of 300-600mg daily are commonly used. Horsetail should not be used for extended periods without medical supervision due to the risk of thiamine deficiency from prolonged consumption. Dosage may vary based on the specific preparation and condition being addressed. Evidence level: C and Traditional use.

Is horsetail safe to take during pregnancy?

No, horsetail is considered unsafe during pregnancy and breastfeeding and should be avoided. The herb contains trace amounts of nicotine and has potent diuretic effects that may disrupt fluid and electrolyte balance during pregnancy. Additionally, prolonged use can deplete thiamine (vitamin B1), which is essential for fetal development. There is insufficient safety data for breastfeeding. Pregnant and nursing women should not use horsetail supplements. Evidence level: C.

Can horsetail cause thiamine deficiency?

Yes, prolonged use of horsetail can cause thiamine (vitamin B1) deficiency. Horsetail contains a thiaminase enzyme that breaks down thiamine in the body, potentially leading to deficiency symptoms including fatigue, confusion, nerve problems, and muscle weakness. This risk increases with long-term consumption. Horsetail is contraindicated in people with existing thiamine deficiency or those at risk. Use should be limited to short periods unless supervised by a qualified healthcare professional. Evidence level: C.

Does horsetail help strengthen bones?

Horsetail has been traditionally used to support bone and connective tissue health due to its exceptionally high silica content, which plays a role in collagen synthesis and bone mineralization. Some preliminary research suggests potential benefits for bone density, but clinical evidence remains limited. The herb should not replace conventional osteoporosis treatments or calcium and vitamin D supplementation. Evidence level: C and Traditional use. Patients with bone conditions should consult a healthcare provider.

PubMed-compiled information sheet

This sheet was compiled from PubMed (NIH) abstracts using AI assistance. Every factual claim is cited to a real PubMed article (see the source list). It has not yet been human-reviewed — confirm with a healthcare provider before use.

Compiled from 29 PubMed articles · model: gemma4:31b

Summary

Equisetum arvense is a perennial plant used traditionally for urinary and inflammatory conditions, demonstrating diuretic and antioxidant properties in various studies [PMID:35998247, 24723963].

Background

Equisetum arvense, commonly known as field horsetail, is a perennial fern [PMID:32486051, 261367 la60]. It is characterized as a silica hyperaccumulator, with amorphous silica (SiO2) accumulating in the outer cell walls of the epidermis [PMID:38615440].

Traditional uses

Traditionally used in medicine for bladder and kidney conditions, to promote wound healing, and for the treatment of inflammatory disorders [PMID:35998247, 37732051].

Active compounds

The plant contains phenolic compounds, flavonoids (including rutin, quercetin, kaempferol, and luteolin), and phenolic acids [PMID:32486051, 36718311]. It is rich in biogenic amorphous silica, containing up to 22-25% SiO2 in dry matter [PMID:38615440, 39685132]. Other identified components include saponins [PMID:7860196] and mixed-linkage (1-->3,1-->4)-beta-D-glucan [PMID:18393951].

Mechanism of action

Horsetail extracts may modulate the function of inflammatory immunocompetent cells [PMID:35998247] and activate SIRT1, which is involved in protecting against oxidative stress, inflammatory processes, and apoptosis [PMID:32486051]. It also demonstrates radical scavenging activity (DPPH and NO) and inhibition of lipid peroxidation [PMID:18719517, 20170379].

Clinical evidence

Evidence BDiuresis

A standardized dried extract (900 mg/day) produced a diuretic effect stronger than a placebo and equivalent to hydrochlorothiazide (25 mg/day) without significant electrolyte changes [PMID:24723963].

Evidence DUrinary Tract Health

Oral intake of aqueous extract stimulates the secretion of Tamm-Horsfall protein (uromodulin) in human urine [PMID:35809378].

Evidence BHypertension

A double-blind, randomized clinical trial was conducted to assess the antihypertensive effect of 900 mg/day of standardized dry extract compared to hydrochlorothiazide [PMID:35168030].

Evidence DDiabetes/Cardioprotection

In streptozotocin-induced diabetic rats, horsetail extract (50-200 mg/kg) modulated insulin sensitivity and activated SIRT1 [PMID:32486051].

Evidence DCancer (In Vitro)

Extracts showed antiproliferative activity against HeLa, HT-29, and MCF7 cell lines [PMID:20170379], and total flavonoids inhibited growth of MCF-7, Caco-2, and HeLa cells [PMID:36718311].

Safety & adverse effects

Oral forms have been implicated in serum aminotransferase elevations, though not convincingly linked to clinically apparent liver injury with jaundice [PMID:35998247]. In rats, a cholesterol-rich diet combined with 4% E. arvense powder caused dermatitis on the neck, head, and back [PMID:9505240]. Adulteration with E. palustre is a concern as that species can produce toxic alkaloids [PMID:26165523, 36235428].

Evidence summary

Evidence consists primarily of in vitro studies, animal models, and a limited number of small-scale human clinical trials (RCTs) focusing on diuretic and antihypertensive effects.

PubMed sources

1.PMID: 28275210 (2017) — Phytomedicine in Joint Disorders. · Nutrients
2.PMID: 35998247 (2012) — Equisetum arvense (common horsetail) modulates the function of inflammatory immunocompetent cells. · CITED REFERENCE
3.PMID: 7860196 (1994) — Urolithiasis and phytotherapy. · International urology and nephrology
4.PMID: 38615440 (2024) — Equisetum arvense as a silica fertilizer. · Plant physiology and biochemistry : PPB
5.PMID: 22228296 (2012) — Equisetum arvense (Field Horsetail)-induced liver injury. · European journal of gastroenterology & hepatology
6.PMID: 9505240

Horsetail Equisetum

Sources & Citations

Calculate a safe dose of Horsetail Equisetum

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Frequently asked questions

Summary

Background

Traditional uses

Active compounds

Mechanism of action

Clinical evidence

Safety & adverse effects

Evidence summary

PubMed sources

Government sources

Horsetail Equisetum

Sources & Citations

Calculate a safe dose of Horsetail Equisetum

Related Herbs

Salsola kali

Capsella Bursa-pastoris Herb

Ground Elder

Frequently asked questions

Summary

Background

Traditional uses

Active compounds

Mechanism of action

Clinical evidence

Safety & adverse effects

Evidence summary

PubMed sources

Government sources