Horsetail (Equisetum arvense)

What is it?

Horsetail (Equisetum arvense) is a perennial plant known for its long, slender, and jointed stems that resemble a horse's tail. It has been used for centuries in traditional medicine for its diuretic, anti-inflammatory, and healing properties. Horsetail is rich in silica, which contributes to its benefits for skin, hair, nails, and bones.

How does it work for medicinal purposes?

Horsetail works through its high silica content and other active compounds. Silica supports the health of connective tissues, promotes collagen formation, and enhances the strength and elasticity of skin, hair, and nails. Horsetail also has diuretic properties, which help reduce fluid retention and support urinary tract health. Its antioxidant and anti-inflammatory effects contribute to overall wellness.

What are the active ingredients that are important for its medicinal properties?

The primary active ingredients in Horsetail include:

• Silica: Strengthens connective tissues, supports collagen production, and enhances skin, hair, and nail health.
• Flavonoids: Provide antioxidant benefits and reduce inflammation.
• Saponins: Have diuretic and anti-inflammatory properties.
• Alkaloids: Contribute to the plant's therapeutic effects.

What forms does it come in?

• Capsules
• Tablets
• Liquid extracts
• Tinctures
• Dried herb (for making teas or infusions)
• Topical creams and ointments

What if I have an imbalance or deficiency?

Horsetail can help address deficiencies or imbalances related to silica, which can lead to weak connective tissues, brittle hair and nails, and poor skin health. Supplementing with Horsetail can help strengthen these tissues and improve overall health.

When was it first used for medicinal purposes?

Horsetail has been used for medicinal purposes since ancient Greek and Roman times. It was traditionally used to treat wounds, support bone health, and promote urinary tract health. Its use has continued through the centuries in various traditional medicine systems.

What does Horsetail (Equisetum arvense) help with?

Horsetail is a green, reed-like plant. People have used it for thousands of years in Europe, China, India, and North America. It is high in silicon, a mineral found in hair, nails, and bone.

The overall grade on file is C. That means the human studies are small, mixed, or early. Most uses below rest on long folk use and lab work, not on trials in people.

• Thinning hair and hair loss
  Early evidence — small, unnamed human supplement studies; no trial size, dose, or journal on file. Some small studies of horsetail supplements reported stronger hair and less breakage. Women with thinning hair were reported to gain thickness and shine after a few months. No trial size, dose, or journal is held in this file.
  Evidence grade C · Traditional tier T3
• Brittle, splitting nails
  Long traditional use · not yet tested in trials — user reports over 6 to 10 weeks; no named human trial on file. Silicon is well established as part of keratin, the protein in nails. That is general nutrition science, not a trial of horsetail. Users of horsetail often report harder, less split-prone nails within 6 to 10 weeks, which is weak evidence.
  Evidence grade D · Traditional tier T3
• Bone strength and bone thinning
  Long traditional use · not yet tested in trials — diet surveys of silicon intake, not trials of horsetail. Silicon is known to play a part in bone building and bone collagen. That is general nutrition science, not a horsetail trial. Diet studies found that people with higher silicon intake had greater bone density, above all in women. Those studies looked at food, not at horsetail.
  Evidence grade D · Traditional tier T3
• Puffiness and mild leg swelling
  Long traditional use · not yet tested in trials — European folk use only; no human trial on file. Herbalists describe horsetail as a gentle diuretic, meaning it raises urine flow. In European herbal practice it is a first choice for mild swelling. No human trial is held in this file, so this rests on long use alone.
  Evidence grade insufficient · Traditional tier T3
• Bladder and urinary tract infections
  Long traditional use · not yet tested in trials — well-recorded folk use and a mechanism idea; no human trial on file. Folk use of horsetail for mild bladder trouble is well recorded. The idea is that more urine flow washes bacteria out. That is a widely accepted mechanism, not a trial result, and no human trial is on file.
  Evidence grade insufficient · Traditional tier T3
• Kidney stones and urinary gravel
  Long traditional use · not yet tested in trials — historic European folk use; no human trial on file. Horsetail was one of the most common European folk remedies for stone prevention. The thinking is that more urine makes it harder for minerals to form crystals. No human trial is held in this file.
  Evidence grade insufficient · Traditional tier T3
• Skin firmness and fine lines
  Long traditional use · not yet tested in trials — general collagen science plus user reports; no human trial on file. Silicon is well established as needed for making collagen, which keeps skin firm. That is general nutrition science, not a horsetail trial. Horsetail appears in some creams and pills, and users report changes after 8 to 12 weeks. No human trial is on file.
  Evidence grade insufficient · Traditional tier T3
• Stiff, sore joints
  Long traditional use · not yet tested in trials — lab work on flavonoids and tradition; human evidence limited. Silica is known as a building block of cartilage, which is general biology. Horsetail holds flavonoids that damped inflammation in lab work. Human evidence for joint stiffness is limited, and no trial is on file.
  Evidence grade insufficient · Traditional tier T3
• Wounds and slow-healing skin sores
  Long traditional use · not yet tested in trials — lab work on flavonoids and saponins, plus historic poultice use. In the past, people laid horsetail poultices on wounds and skin sores. Lab work points to germ-fighting and healing action from its flavonoids and saponins. No human trial is held in this file.
  Evidence grade insufficient · Traditional tier T3

What Horsetail (Equisetum arvense) has not been shown to do

• No trial on file shows horsetail clears a urinary tract infection or stands in for antibiotics.
• No trial on file shows it dissolves kidney stones or helps stones pass.
• It has not been shown to reverse osteoporosis; the bone data on file came from silicon in food, not from horsetail.
• Human evidence for arthritis pain is limited, so relief of arthritis has not been shown.
• The hair reports on file were in women with thinning hair, not in male pattern baldness.
• No trial on file compares horsetail with prescription water pills for swelling.
• No trial on file shows that it smooths wrinkles.

How to read this:

Grades run from A to D, plus insufficient. A means steady randomised trials in people. B means at least one good trial. C means small or early human studies. D means weak or mixed human evidence. Insufficient means no human study on file, only lab work, animal work, or tradition. This page lists options and what studies found. It is not medical advice, and it is not a claim that horsetail works for you.

What can Horsetail (Equisetum arvense) help prevent?

• Recurrence of urinary tract infections (by maintaining high urine flow and flushing the bladder regularly)
• Kidney stone formation (by reducing mineral concentration in urine through increased output)
• Age-related bone density loss (by supporting silicon-dependent bone mineralization, as a complement to calcium and vitamin D)

Which foods are rich in it?

Horsetail is not typically found in foods and is primarily consumed as a dietary supplement or herbal remedy.

What are possible side effects?

Horsetail is generally well-tolerated, but possible side effects include:

• Common (10-30%)
• Mild gastrointestinal issues (e.g., nausea, diarrhea, stomach discomfort)
• Less Common (1-10%)
• Headache
• Dizziness
• Rare (<1%)
• Allergic reactions (e.g., rash, itching)
• Low potassium levels (hypokalemia) with excessive use
• Thiamine (vitamin B1) deficiency with prolonged use due to thiaminase enzyme in Horsetail

What’s the recommended daily dose?

The recommended daily dose of Horsetail for adults typically ranges from 300 to 900 mg of standardized extract, divided into two or three doses. For dried herb, 2 to 3 grams per day infused in tea is common. It is important to follow the dosage instructions provided on the product label or by a healthcare provider.

How many days does it take to work?

Some benefits of Horsetail, such as improved skin and hair health, may be noticeable within a few weeks. Long-term benefits, such as enhanced bone density and reduced joint inflammation, may take several months of regular use to become apparent.

What time of day is best to take it?

Horsetail can be taken at any time of day. Dividing the daily dose into two or three smaller doses may help maintain consistent levels in the body and improve efficacy.

Is it best to take it with or without food?

Horsetail can be taken with or without food. Taking it with meals may help minimize any potential gastrointestinal discomfort. For optimal absorption and efficacy, follow the instructions provided on the product label.