Horsetail is a fern-like plant used for centuries as a natural remedy, and modern research supports several of its traditional uses. Its standout feature is an unusually high silicon content, with silicic acid and silicates making up 5 to 8% of the plant’s dry weight. This mineral concentration, combined with a rich profile of antioxidant compounds, gives horsetail measurable effects on bone health, fluid balance, skin repair, and more.
Bone and Joint Support
Silicon is a trace mineral your body uses to build and maintain connective tissue, and horsetail is one of the richest plant sources available. The silicon in horsetail contributes to bone mineralization by stimulating the cells responsible for building new bone tissue. Several plant compounds in horsetail, including quercetin and kaempferol, have been shown to promote bone cell growth, differentiation, and mineralization through multiple signaling pathways. Other compounds in the plant, like apigenin, increase the activity of alkaline phosphatase, an enzyme essential for laying down new mineral in bone.
Beyond silicon, horsetail contains smaller but meaningful amounts of calcium (1.3%), potassium (1.8%), magnesium, and manganese, all of which play roles in skeletal health. This combination of minerals and bone-stimulating plant compounds is why horsetail appears frequently in herbal formulas marketed for osteoporosis support, though it works best as a complement to adequate calcium and vitamin D intake rather than a standalone treatment.
Natural Diuretic Effect
Horsetail has a well-documented ability to increase urine output. A randomized, double-blind clinical trial in healthy volunteers found that horsetail extract produced a diuretic effect equivalent to hydrochlorothiazide, a commonly prescribed pharmaceutical diuretic. The key difference: horsetail achieved this without causing significant changes in electrolyte levels, which is a common side effect of conventional diuretics that can lead to muscle cramps or heart rhythm issues.
This diuretic property makes horsetail a popular choice for mild fluid retention and bloating. It has a long history of traditional use for urinary tract support, and the increased urine flow may help flush the urinary system. Animal studies have also shown that horsetail extract reduces paw swelling caused by inflammation, suggesting the fluid-balancing effect extends to inflammatory edema as well.
Antioxidant and Anti-Inflammatory Properties
Horsetail contains a dense concentration of phenolic compounds that act as free radical scavengers in the body. These fall into several categories, each contributing different protective effects. Hydroxycinnamic acids like ferulic, caffeic, and sinapic acid are known for antioxidant, anti-inflammatory, and even neuroprotective activity. Hydroxybenzoic acids, another major group, add further anti-inflammatory capacity.
The flavonoid content is equally impressive. Horsetail contains derivatives of myricetin, quercetin, and kaempferol, both in free form and bound to sugars. These flavonoids are among the most studied plant antioxidants, with established roles in reducing oxidative stress and calming inflammatory pathways. Horsetail also contains stilbenoids, a class of compounds related to resveratrol, which adds another layer of antioxidant protection. Together, this phytochemical profile explains why horsetail has shown broad protective effects in laboratory and animal studies across multiple body systems.
Skin and Wound Healing
Silicon plays a central role in collagen production, the protein that gives skin its structure and elasticity. Horsetail’s high silicon content is the primary reason it shows up in skin care supplements and topical preparations. Research in diabetic rat models, where wound healing is notoriously slow, demonstrated that topical ointments containing 5% and 10% horsetail extract increased wound closure rates to 99.71% and 99.93%, respectively. The extract worked by boosting fibroblast collagen synthesis while also enhancing regeneration of both the outer skin layer and the deeper dermal tissue.
These wound healing effects involved modulation of inflammatory signaling molecules, meaning horsetail didn’t just speed up tissue repair but also helped regulate the inflammatory environment around the wound. For everyday use, horsetail’s collagen-supporting properties are the main draw for people interested in skin firmness, hair strength, and nail health, all tissues that depend heavily on silicon and collagen.
How to Take Horsetail
Horsetail is available as capsules, teas, tinctures, and topical preparations. For capsules, look for a product standardized to contain 10 to 15% silica, which ensures a consistent and meaningful dose of the plant’s key mineral. For tea, the standard preparation is 2 to 3 teaspoons of dried herb steeped in hot water for 5 to 10 minutes, taken up to three times daily.
Most herbalists recommend cycling horsetail rather than taking it continuously. The plant contains thiaminase, an enzyme that breaks down vitamin B1 (thiamine). Over weeks or months of uninterrupted use, this could theoretically contribute to thiamine depletion, which affects energy metabolism and nerve function. Taking breaks, or supplementing with a B-complex vitamin alongside horsetail, minimizes this risk. People on lithium or other medications affected by fluid balance should be cautious, since horsetail’s diuretic effect can alter how the body processes certain drugs.
Cooking or thoroughly drying horsetail inactivates much of the thiaminase, which is one reason traditional preparations favor tea over raw consumption. Quality also matters: horsetail can accumulate heavy metals from contaminated soil, so purchasing from a reputable brand that tests for contaminants is worth the extra cost.