Horsetail is an herbal remedy traditionally used for its many health-promoting effects. Potential benefits include promoting hair, skin, and nail health. However, limited scientific evidence supports this.
Horsetail is a popular fern that has been used as an herbal remedy since the times of the Greek and Roman Empires (1, 2).
It’s believed to have multiple medicinal properties and has traditionally been used to treat wounds; to enhance skin, hair, and bone health; and as a remedy for various other health conditions (1, 3).
However, there is not enough human evidence to support many of the traditional uses for horsetail
This article explores horsetail, including its potential benefits, uses, and downsides.
What is horsetail?
Field or common horsetail (Equisetum arvense) is a perennial fern that belongs to the genus Equisetaceae (3, 4).
It grows wild in northern Europe and North and Central America, as well as in other moist places with temperate climates. It has a long, green, densely branched stem that grows from spring to fall (1, 4).
The plant contains numerous beneficial compounds that give it multiple health-promoting effects. Of these, antioxidants and silica stand out (1, 4).
Antioxidants are molecules that protect your body from the effects of free radicals that can cause cell damage. Silica is a compound made up of silicon and oxygen and is believed to be responsible for horsetail’s potential benefits for skin, nails, hair, and bones (3, 4).
Horsetail is mostly consumed in the form of tea, which is made by steeping the dried herb in hot water. It’s also available in capsule and tincture form.
SummaryHorsetail is a fern that contains many beneficial compounds, notably antioxidants and silica. It’s found in the form of tea, tinctures, and capsules.
Share on PinterestHorsetail’s potential benefits
Horsetail has been used for thousands of years as an herbal remedy, and limited scientific evidence supports its potential benefits.
Supports bone health
Research suggests that horsetail may aid bone healing.
Through bone metabolism, bone cells called osteoclasts and osteoblasts continuously remodel your bones to avoid imbalances that could cause brittle bones. Osteoblasts handle bone synthesis, while osteoclasts break down bone through resorption.
Test-tube studies show that horsetail may inhibit osteoclasts and stimulate osteoblasts. This suggests that it’s useful for bone diseases such as osteoporosis, which is characterized by overly active osteoclasts that result in fragile bones (1, 5).
One study in rats found that a daily dose of 55 mg of horsetail extract per pound (120 mg per kg) of body weight significantly improved bone density, compared with a control group (6).
Researchers believe that horsetail’s bone-remodeling effect is mostly due to its high silica content. In fact, up to 25% of its dry weight is silica. No other plant boasts as high of a concentration of this mineral (1, 5).
Silica, which is also present in bones, improves the formation, density, and consistency of bone and cartilage tissue by enhancing collagen synthesis and improving the absorption and use of calcium (6, 7).
Acts as a natural diuretic
Diuretics are substances that increase your body’s excretion of urine. Horsetail’s diuretic effect is one of this fern’s most sought-after properties in folk medicine (8, 9).
One small study in 36 healthy men determined that a daily dose of 900 mg of dried horsetail extract in capsule form had a more potent diuretic effect than a classic diuretic drug. This was attributed to the plant’s high antioxidant and mineral salt concentrations (9).
The plant also demonstrated potential as a therapy for urinary incontinence, urgency, and nocturia — when you wake up in the night to urinate (10).
A 2021 review of research found that horsetail may have potential as a therapy for kidney conditions, including urethritis and kidney stones (8).
However, while these results are promising, current human research is limited.
Promotes wound healing and nail health
The topical application of horsetail ointment appears to promote wound healing.
One 10-day study in 108 postpartum women who had undergone an episiotomy during labor — a surgical cut to facilitate childbirth — showed that applying an ointment containing 3% horsetail extract promoted wound healing and helped relieve pain (11).
The study also found that wound redness, swelling, and discharge improved significantly compared with a control group. Scientists attributed these positive effects to the plant’s silica content.
In older rat studies, those treated with ointments containing 5% and 10% horsetail extract showed a wound closure ratio of 95–99%, as well as greater skin regeneration, compared with control groups (12, 13).
Additionally, horsetail extract may be used in nail polish for the management of nail psoriasis, a skin condition that causes nail deformities.
One study found that using a nail lacquer made up of a mixture of horsetail extract and other nail-hardening agents decreased signs of nail psoriasis (14, 15).
However, research on the direct effect of horsetail on wound healing and nail health is needed to verify these benefits.
Promotes hair growth
Research suggests that horsetail may also benefit your hair, likely thanks to its silicon and antioxidant content.
First, antioxidants help reduce micro-inflammation and the aging of hair fibers caused by free radicals. Second, a higher silicon content in hair fibers results in a lower rate of hair loss, as well as increased brightness (16, 17, 18).
For example, in a 3-month study in women with self-perceived hair thinning, those who took two daily capsules containing dried horsetail and other ingredients had increased hair growth and strength compared with a control group (19).
Other studies looking at the effects of different blends containing horsetail-derived silica found similar results (20, 21).
However, because most studies focus on a mixture of multiple hair growth compounds, research on the effects of horsetail alone is still limited.
Other potential benefits
Horsetail is known for providing many other potential benefits, including:
- Anti-inflammatory activity. Test-tube studies show that horsetail extract may inhibit lymphocytes, the main type of defense cells involved in inflammatory immune diseases (4, 22, 23).
- Antimicrobial activity. Horsetail essential oil seems to have potent activity against bacteria and fungi, including Staphylococcus aureus, Escherichia coli, Aspergillus niger, and Candida albicans (4, 24).
- Antioxidant activity. Research shows that horsetail is rich in phenolic compounds, a group of powerful antioxidants that inhibit oxidative damage to cellular membranes (4, 25, 26).
- Antidiabetic effects. Animal and test-tube studies suggest that horsetail extract may help lower blood sugar levels and regenerate damaged pancreatic tissue (27, 28).
Horsetail has multiple potential health benefits, including improved bone, skin, hair, and nail health.
Uses and dosage
Most horsetail products available are marketed as skin, hair, and nail remedies. However, you may also find products claiming to manage urinary and kidney conditions (3).
As for the dosage, one human study suggests that taking 900 mg of horsetail extract capsules — the maximum recommended daily dose for dry extracts, according to the European Medicines Agency — for 4 days may produce a diuretic effect (9).
However, an appropriate dose has yet to be determined by current scientific evidence.
SummaryHorsetail is mostly used as a skin, hair, nail, and urinary remedy. A dose of 900 mg daily for 4 days may have a diuretic effect, but overall, an appropriate dose has yet to be determined.
Side effects and precautions
Like most other herbal supplements, horsetail has not been approved by the Food and Drug Administration (FDA), and people who are pregnant and breastfeeding should avoid it.
While research in rats suggests that it’s not toxic, human studies are needed (29).
Horsetail may cause drug-herb interactions when consumed alongside antiretroviral drugs prescribed for HIV treatment (30).
In people with kidney disease, horsetail may increase potassium to unsafe levels. People with kidney disease generally should not use horsetail or other herbal supplements (31).
Additionally, the plant contains nicotine, so you should avoid it if you have a nicotine allergy or want to quit smoking (32).
What’s more, in one case, a 56-year-old woman experienced pancreatitis — inflammation of the pancreas — as a result of drinking horsetail tea. Her symptoms ceased when she stopped drinking the tea (33).
Lastly, horsetail has a reported thiaminase activity. Thiaminase is an enzyme that breaks down thiamine, or vitamin B1.
Thus, long-term horsetail intake, or any horsetail intake in those with low thiamine levels — such as people with alcohol use disorder — may lead to vitamin B1 deficiency (34).
SummaryGiven that horsetail is an herbal remedy, it’s not approved by the FDA. Pregnant and breastfeeding people, people with low vitamin B1 levels, people with kidney disease, and those who take antiretroviral drugs should avoid consuming it.
The bottom line
Horsetail has been used as an herbal remedy for centuries.
It’s mostly used for skin, hair, nail, and urinary conditions, and it may be consumed in the form of tea, capsules, and tinctures.
However, it’s not approved by the FDA and should be avoided by pregnant and breastfeeding people, people with low vitamin B1 levels, and those who take antiretroviral drugs.