Does horsetail actually help hair, nails, bones or wound healing?

Silicon is the second most abundant element on Earth, yet it's often overlooked as a nutrient. In the body, silica (silicon dioxide) is woven into the structure of collagen — the scaffolding protein behind bones, skin, tendons, and blood vessel walls. Without adequate silicon, collagen formation is impaired and structural tissues become weaker over time.

Horsetail contains silicon primarily as water-soluble silicic acid, which is more bioavailable than crystalline silica found in soil. Studies on bioequivalent forms show that supplemental silicon can measurably improve hair tensile strength and reduce brittleness in both hair and nails^2,3.

Bone Density

A large epidemiological study in the Framingham Offspring cohort (2,847 adults) found that dietary silicon intake was positively associated with cortical bone mineral density in men and premenopausal women¹. The association was seen after adjusting for confounding factors known to influence bone density and nutrient intake. Animal studies using horsetail extract specifically found significant increases in bone mineral density compared to controls⁶.

This does not mean horsetail replaces calcium or vitamin D — those remain foundational — but adequate silicon appears to be a co-factor in bone matrix formation that many people overlook.

Hair and Nails

Two double-blind, placebo-controlled trials in women tested oral silicon supplementation (10 mg/day as choline-stabilized orthosilicic acid) and found:

• Reduced hair brittleness scores and improved break load and elasticity after 9 months²
• Reduced nail brittleness and improved skin surface texture after 20 weeks³

Horsetail tea and standardized extracts are commonly used as food-form sources of silicon for the same purposes.

Anti-Inflammatory and Wound Healing Effects

Beyond silica, horsetail contains flavonoids (including kaempferol and quercetin derivatives) and phenolic acids that contribute to its anti-inflammatory action. An extract of E. arvense stems reduced carrageenan-induced paw edema by 25–30% in animal models at 50 mg/kg⁴. In vitro work on human lymphocytes shows that horsetail preparations suppress lymphocyte activation and proliferation through an interleukin-2-dependent mechanism, and that silica is not the only active compound (isoquercitrin is active too) — meaning the anti-inflammatory action isn't just due to silica⁹.

Clinically, a 3% horsetail ointment applied topically significantly accelerated wound healing and reduced pain scores compared to placebo in a randomized controlled trial following episiotomy⁵. This is consistent with silica's role in collagen synthesis and tissue regeneration.

How to Use Horsetail

• Tea: Steep 2–3 g of dried horsetail herb in hot water for 10–15 minutes. Drink 1–3 cups daily.
• Capsule/extract: Standardized extracts providing 5–10 mg elemental silicon per dose are commonly used. Look for products standardized to silicic acid content.
• Topical: Ointments and creams (2–3%) are used for wound care and skin support.

Duration: Most studies ran for 9–20 weeks. Short-term use is well-studied; long-term use beyond several months should be approached with awareness of the safety notes below.

A Note on Safety

Horsetail contains a small amount of thiaminase, an enzyme that can deplete vitamin B1 (thiamine) with prolonged high-dose use. This is generally not a concern at typical supplemental amounts or with dietary tea consumption, but very long-term or high-dose supplementation should be cycled. Standardized extracts have had thiaminase deactivated in processing.

The NIH LiverTox database considers standard doses (up to ~6 g/day dried herb) generally well-tolerated, with rare isolated cases of liver enzyme elevation⁷. Horsetail is typically avoided during pregnancy due to lack of safety data.

Avoid confusing Equisetum arvense (common horsetail) with E. palustre (marsh horsetail), which has higher alkaloid content and is not used medicinally.

See also the Silica-rich sea vegetables page and our MSM page for other sulfur- and mineral-rich connective tissue supports.

Silicon and Bone Mineral Density

The strongest human evidence for silicon's role in bone health comes from the Framingham Offspring cohort study (Jugdaohsingh et al., 2004)¹. This observational study in 2,847 adults found that dietary Si intake was a significant positive predictor of cortical bone mineral density (BMD) in men (p < 0.001) and premenopausal women (p = 0.04), independent of calcium, phosphorus, and other established bone nutrients. The association was not significant in postmenopausal women not on hormone therapy, suggesting an interaction with estrogen status.

Animal evidence for horsetail extract specifically was provided by Arbabzadegan et al. (2019)⁶, who found that a diet containing 120 mg/kg E. arvense extract significantly increased mandibular BMD in Wistar rats compared with the control group, as measured by digital radiography. A separate study in an ovariectomized rat model of osteoporosis (Kotwal and Badole, 2016)⁸ added E. arvense to a supplement of calcium, vitamin D, L-lysine, L-proline, L-arginine, and L-ascorbic acid. Both the supplement alone and the supplement with E. arvense produced significant changes in bone formation and resorption markers, cortical bone thickness, and trabecular width, and the version with E. arvense also restored the lipid profile to near normal; the authors found it as effective as the osteoporosis drug raloxifene in reversing the osteoporotic changes.

Limitations: Human RCT data for horsetail extract on bone density are lacking. The Framingham data reflect dietary silicon broadly (from grains, vegetables, and water) — not horsetail supplementation specifically. Translating animal and epidemiological data to clinical practice requires caution.

Hair and Nail Silicon RCTs

Barel et al. (2005)³ conducted a double-blind, placebo-controlled trial (n=50) using 10 mg/day of choline-stabilized orthosilicic acid (ch-OSA) for 20 weeks in women with photodamaged skin. The silicon group showed significant improvements in nail brittleness scores and skin roughness vs. placebo. Hair brittleness also trended toward improvement.

Wickett et al. (2007)² extended this with a 9-month double-blind RCT in 48 women with fine hair. The ch-OSA group (10 mg Si/day) showed statistically significant improvements in hair tensile break load (+13% vs. placebo, p < 0.05), elasticity, and hair cross-sectional area. This is a robust, well-designed trial with clinically meaningful outcomes.

Important note: Both trials used ch-OSA — a specific bioavailable silicon form — not horsetail tea directly. Horsetail is a food source of silicic acid with likely lower and more variable bioavailability per dose. The trials establish that silicon bioactivity for hair and nails is real; whether tea or standard extracts deliver equivalent doses requires individual consideration.

Anti-Inflammatory Mechanisms

Martins Do Monte et al. (2004)⁴ demonstrated that a hydroalcoholic extract of E. arvense stems reduced carrageenan-induced paw edema by 25–30% at 50 mg/kg in mice, with peak activity at 3–4 hours post-challenge, consistent with inhibition of the prostaglandin-mediated phase of inflammation. The extract also showed antinociceptive effects in the writhing and hot-plate tests.

A more mechanistic in vitro study (Steinborn et al., 2018)⁹ found that E. arvense preparations suppress the activation and proliferation of primary human lymphocytes through an interleukin-2-dependent mechanism, with the effect increasing as the silica concentration of the decoctions rose; lymphocyte polyfunctionality was also affected, with a downregulation of IFN-γ. Importantly, profiling identified isoquercitrin as a second component present at immunosuppressive concentrations, and the authors concluded that both silica and isoquercitrin are active compounds, so the plant's anti-inflammatory effects are not solely mediated by its mineral content.

Strength of evidence: Anti-inflammatory evidence is primarily animal and in vitro. Clinical anti-inflammatory applications are not yet supported by human RCTs.

Wound Healing

Asgharikhatooni et al. (2015)⁵ conducted the most rigorous human clinical trial: a randomized, placebo-controlled study in women who received topical 3% E. arvense ointment vs. placebo after episiotomy (n=108). The horsetail group showed significantly faster wound healing (assessed via REEDA scale at days 5, 10) and lower pain scores (VAS) compared to the Vaseline placebo group. This is a high-quality clinical trial with a meaningful patient population.

Animal wound-healing work points the same way: in a rat study of dermal wounds (Ozay et al., 2010)¹⁰, the E. arvense ointment groups (5% and 10%) had wound closure ratios of 95.26% and 99.96% after 14 days, with higher dermal and epidermal regeneration, angiogenesis, and granulation tissue thickness than the other groups. The Vaseline-lanolin base alone also improved wound closure compared with untreated wounds.

Clinical relevance: Topical horsetail is the best-supported application, particularly for tissue repair. The mechanism likely involves both silica (collagen synthesis) and flavonoid-mediated reduction of wound-site inflammation.

Overall Evidence Quality

Application	Evidence Level	Human RCT?
Hair/nail strength (silicon)	Moderate	Yes (ch-OSA form)
Bone mineral density	Moderate (epidemiological)	No (animal only for E. arvense)
Wound healing (topical)	Moderate	Yes
Anti-inflammatory	Low–Moderate	No

The evidence base supports cautious, targeted use — particularly for hair/nail brittleness and topical wound support. Bone density benefits are plausible based on silicon's role in collagen metabolism but require more direct human trial evidence before strong recommendations can be made.