What Is Horsetail?

Horsetail (Equisetum arvense) is an herb in the Equisetaceae family of plants. It's also called "bottle-brush" or "horse herb."

People have been using horsetail since ancient Greek and Roman times. The plant has been used as a medicinal herb to treat bone loss (osteoporosis), tuberculosis, and kidney problems. Some have claimed that horsetail can help relieve fluid retention (diuretic), stop bleeding, and heal wounds.

While it has been used for a long time, there is no good research on how well horsetail works or how safe it is for humans. This article will go over what studies have found about using horsetail. It will also teach you about how horsetail has been used and what you should know before trying it.

What Is Horsetail Used For?

In alternative medicine, herbs like horsetail have been used for many thousands of years to treat health problems. However, there is not enough research on horsetail to know if it will help these conditions. It's also not clear if it's safe for humans to use.

Here are a few examples of conditions that some people claim horsetail may help:

• Bleeding
• Gout
• Frostbite
• Heavy menstrual periods
• Inability to control the bladder (incontinence)
• Kidney or bladder stones
• Osteoarthritis
• Urinary tract infections
• Weight loss
• Wounds

Research on Horsetail

Products that have horsetail in them may claim to help or even treat medical conditions. However, there is not enough research to support the claims. The research on horsetail that has been done was mostly in animals, not people. The results of those studies could help us learn about horsetail but do not necessarily apply to humans.

Here are a few studies that have looked at how horsetail could be used for health problems.

Osteoporosis

Osteoporosis is a condition that causes softening or thinning of the bone tissue. It often occurs in people who are going through menopause. Horsetail contains silicon, a mineral needed for healthy bone and connective tissue production.

Some studies have looked at whether horsetail can help treat osteoporosis, but they were not done in people. Instead, the researchers used animals who had their ovaries taken out. That made them similar to a person who is in menopause.

For example, a 2016 study published in the Indian Journal of Pharmacology found that calcium, vitamin D, zinc -lysine, L-proline, L-arginine, and L-ascorbic acid (N) helped bones form faster in rats. Adding a horsetail extract to the treatment seemed to help with bone formation.

The study only looked at bone formation in rats. It's not clear if the same benefits would happen in humans with osteoporosis.

Hair Growth

Horsetail has an amino acid called cysteine in it. The herb also contains minerals such as selenium, which is known to enhance hair growth.

Blood Sugar

Another study in rats that was published by the Pakistan Journal of Biological Sciences found that horsetail may help lower blood sugar (glucose) levels. However, because the study was done using animals, more research needs to be done with humans to see if it would help and be safe to use.

How Does Horsetail Work?

Certain chemicals in horsetail are thought to lower inflammation. They might also help the body make more substances that boost the immune system (antioxidants).

Horsetail also has silica and silicon in it. These minerals work together to strengthen the hair and nails. They also help the body make healthy bone tissue.

Selenium, another mineral that has been shown to help hair grow, is also found in horsetail.

Possible Side Effects

The Food and Drug Administration (FDA) says that horsetail is an herb of undefined safety. That means that there is not enough research evidence to prove that horsetail is safe to use or that it works for treating health conditions. The FDA has not approved horsetail for any use.

Special Warning

Horsetail has an enzyme called thiaminase in it. The enzyme breaks down thiamine, which is also called vitamin B1. When thiamine is broken down, it becomes useless to the body.

If you take too much horsetail or take it for a long time, you might not have enough thiamine in your body (thiamine deficiency).

Contraindications

A contraindication means that you should not take a medication or supplement because it might cause a bad reaction. Medical conditions, medications, other products you use, and treatments can all be contraindications.

Horsetail has several known contraindications. If any of these situations apply to you, do not use horsetail.

• Alcohol use disorders: Horsetail makes the body less able to use thiamine. Drinking a lot of alcohol can make you more likely to have a thiamine deficiency.
• Thiamine deficiency: Horsetail breaks thiamine in half. This makes it useless in the body. If this happens, you may not have enough thiamine to meet your body's needs (thiamine deficiency). Your provider might want you to take a B complex or multivitamin daily if you use horsetail to help prevent a thiamine deficiency.
• Pregnancy or breastfeeding: There has not been enough research on using horsetail when you are pregnant or breastfeeding to show that it is safe.
• Diabetes: Horsetail is thought to lower blood sugar. Having blood sugar levels that are too low is called hypoglycemia. If a person with diabetes gets very low blood sugar levels, it can be life-threatening.
• Low potassium: Horsetail has a "fluid-flushing" effect. This is called a diuretic. When you lose a lot of fluid from your body, you also lose an important nutrient called potassium. If your levels of potassium get too low, it's called hypokalemia. This condition can be very dangerous because it can make your heart not work properly.

Drug Interactions

If you are taking certain medications, horsetail could affect how they work. You should not use horsetail if you are taking:

• Lithium: The "fluid-flushing" effect of horsetail can change how fast lithium leaves your body. If this happens, you might not have the right amount of lithium in your body. This could cause side effects or make the medication not work right.
• Diabetic drugs: Actos (pioglitazone), Amaryl (glimepiride), Avandia (rosiglitazone), Diabeta (glyburide), Glucotrol XL (glipizide), insulin, and other medicines used to treat diabetes should not be taken with horsetail. Horsetail might lower your blood sugar levels. If you take it with insulin or other diabetic drugs, you could get dangerously low blood sugar levels.
• Diuretics: Medications (sometimes called "water pills") that "flush" fluid from your body can also make your potassium levels low. Examples of these medications are Diuril (chlorothiazide), Lasix (furosemide), Microzide (hydrochlorothiazide), and Thalitone (chlorthalidone). A small randomized, double-blind study found that horsetail also had a fluid-flushing effect. If you use horsetail with another fluid-flushing medication, your potassium levels might get too low.
• Nicotine patches or nicotine gum: Horsetail has nicotine in it. You should not use horsetail if you use nicotine gum or nicotine replacement patches.
• Lanoxin (digoxin): If horsetail lowers your potassium levels, it can affect the beating of your heart. People who already have problems with how their heart is beating (arrhythmia) or take a medication called digoxin should not take horsetail.

Selection, Preparation, & Storage

Medicinal preparations made with horsetail from Equisetum are usually considered safe. However, another species of horsetail named Equisetum palustre was found to be poisonous to horses.

Preparation

Horsetail comes as a dried herb. You can use it as tea and in other mixtures. You can also get horsetail in a liquid, a concentrated liquid called a tincture, or in a capsule.

Here are a few examples of the doses of horsetail you might see in different products:

• A capsule: A standard dose has 10% to 15% silica in a capsule.
• An herbal infusion: 2 to 3 teaspoons of dried horsetail taken three times per day
• A tincture: The dosage should be chosen by your provider, but the ratio for making the tincture is 1-to-5.
• A compress (for wounds or skin treatment): 10 grams of herb per 1 liter (33.8 ounces) of water each day

Here are a few examples of how much horsetail might be used for different conditions. However, you need to talk to your provider about the dose that will be right for you.

• Brittle nails: Products like creams that go on your skin may have horsetail in them. In studies, these products were applied every night for 29 days (or every other day for 14 days).
• Diuretic: In one study, a dry extract of horsetail containing 0.026% total flavonoids was given as a 300 mg dose that a person took by mouth three times a day.
• Wound healing: In one study, a 3% horsetail ointment was put on the episiotomy site of people who had recently given birth (postpartum) every 12 hours for 10 days.
  

Storage

Like many prescription medications, herbal products need to be stored properly to make sure they keep working. All preparations of horsetail should be kept in a sealed dark container. They need to be protected from exposure to light.

Summary

Horsetail is a plant that has been used for thousands of years. It's often found in products that are meant to help with hair growth or bone health. However, there is not enough research to prove that it is can treat medical conditions or is safe to use.

The FDA has not approved horsetail to treat any medical conditions. Herbal products like horsetail are also not regulated by the FDA.

A Word From Verywell

Always talk to your healthcare provider before taking an herbal supplement like horsetail. It's not OK to use horsetail if you take certain medications or have some health conditions.

There are different ways to use horsetail. It also comes in different amounts. If your provider thinks that it's fine for you to try horsetail, they will help you figure out which type to take and how much to use.