Horsetail oil is made by infusing dried horsetail herb into a carrier oil over several hours or weeks, extracting the plant’s silica and minerals into a form you can apply directly to your scalp. The process is simple, requires no special equipment, and gives you a shelf-stable oil that lasts up to a year when stored properly.
Why Horsetail Works for Hair
Horsetail (Equisetum arvense) contains one of the highest concentrations of silicon found in any plant. Silicon is a building block your body uses to strengthen keratin, the protein that makes up each strand of hair. When silicon is absorbed, it’s converted into a form called orthosilicic acid, which activates fibroblasts, the cells responsible for producing the structural proteins and signaling molecules that support hair growth.
The clinical evidence is encouraging. In a 9-month randomized, placebo-controlled study, women with fine hair who took a silica supplement derived from this same compound showed significantly thicker hair, measured by the cross-sectional area of individual strands, along with improved tensile strength. A separate 20-week trial found that participants using the same type of silica had measurably less hair brittleness compared to those on a placebo. These studies used oral supplements rather than topical oil, so the effects of applying horsetail directly to the scalp are less well-documented. Still, topical application delivers silica and antioxidants directly to the hair follicle environment, which is why herbalists have used it this way for centuries.
What You’ll Need
- Dried horsetail herb: About half a cup (roughly 15 to 20 grams). Dried is better than fresh because excess moisture in fresh plant material can introduce bacteria and cause the oil to spoil. You can find dried horsetail at herbal shops, health food stores, or online.
- Carrier oil: One cup (about 240 ml). Olive oil, jojoba oil, and sweet almond oil are all good choices. Jojoba closely resembles your scalp’s natural sebum and absorbs well. Olive oil is heavier and works better for very dry or coarse hair. Coconut oil is another option, though it solidifies at cool temperatures, which can make application less convenient.
- A clean glass jar with a tight-fitting lid.
- A dark glass bottle for storing the finished oil.
- Cheesecloth or a fine mesh strainer.
Slow Infusion Method (Cold)
This is the gentlest approach and preserves the most delicate plant compounds. Place the dried horsetail in your glass jar and pour the carrier oil over it, making sure the herb is fully submerged. Seal the jar tightly.
Set the jar in a sunny windowsill or another warm spot in your home. Let it sit for 2 to 4 weeks, shaking it gently once a day to help the extraction along. The warmth from sunlight speeds up the process without damaging heat-sensitive compounds. After the infusion period, strain the oil through cheesecloth into your dark glass storage bottle, squeezing the herb bundle to get every last drop of infused oil out.
Heat Infusion Method (Faster)
If you don’t want to wait weeks, heat speeds up the extraction significantly. Place the dried horsetail and carrier oil in a double boiler or a heat-safe jar set inside a pot of water. Warm the oil on the lowest heat setting for 2 to 3 hours, keeping the temperature below about 50°C (120°F). You want the oil warm to the touch but never simmering. Higher heat breaks down beneficial compounds and can turn the oil rancid faster.
Stir occasionally. The oil will gradually take on a greenish or golden-brown tint as it draws out the plant’s constituents. Once finished, let it cool completely, then strain through cheesecloth into your dark glass bottle. This method produces an oil that’s ready to use the same day.
Optional Additions
Some people add a few drops of essential oil to their finished horsetail oil for extra scalp benefits or a more pleasant scent. Rosemary essential oil is a popular choice because it has its own evidence for supporting hair growth. Peppermint oil creates a tingling sensation that increases blood flow to the scalp. Use no more than 10 to 15 drops of essential oil per cup of carrier oil to avoid skin irritation. Add these after straining, not during the infusion.
You can also combine horsetail with other dried herbs in the same infusion. Nettle leaf and calendula are common companions. Nettle is rich in minerals, while calendula soothes the scalp. If you add other herbs, keep the total amount of dried plant material to about half a cup per cup of oil so the herbs stay fully submerged.
How to Use It
Apply the oil directly to your scalp, not just your hair. Part your hair into sections and use a dropper or your fingertips to distribute the oil along your scalp. Massage it in with gentle circular motions for 3 to 5 minutes. This massage step matters because it increases blood circulation to the follicles, which supports nutrient delivery on its own.
For a deep treatment, leave the oil on for at least 30 minutes or overnight with a towel over your pillow. Wash it out with your regular shampoo. You may need to shampoo twice to fully remove the oil, especially if you used olive or coconut oil as your base. Most people use horsetail oil 2 to 3 times per week. Given that the clinical studies showing thicker hair ran for 9 months and 20 weeks respectively, consistency over several months matters more than frequency in any single week.
Storage and Shelf Life
Transfer your finished oil into a dark glass bottle, amber or cobalt blue, to protect it from light. Light and heat both degrade the oil over time. Keep it in a cool, dark place like a cabinet or closet. Label the bottle with the date you made it so you can track freshness.
Properly stored horsetail oil lasts 6 to 12 months. Check it periodically by smelling it. Fresh herbal oil has a mild, earthy, slightly grassy scent. If it smells sharp, sour, or unpleasant, the oil has gone rancid and should be discarded. Using a carrier oil with a naturally long shelf life, like jojoba, gives you the longest-lasting infusion. Olive oil is moderately stable. Sweet almond oil tends to go rancid a bit sooner.
Safety Considerations
Topical horsetail oil is well tolerated by most people, but there are a few things to watch for. There is at least one documented case of contact dermatitis triggered by compounds in horsetail, and rare allergic reactions have been reported, particularly in people with existing allergies to carrots and related plants. Before using horsetail oil on your entire scalp, apply a small amount to the inside of your wrist and wait 24 hours to check for redness or irritation.
When sourcing dried horsetail, buy from a reputable supplier. Horsetail products have occasionally been found contaminated with a related species called Equisetum palustre, which contains different chemical compounds and is not suitable for use. A trusted herbal supplier will sell clearly identified Equisetum arvense. If you’re pregnant or breastfeeding, there isn’t enough safety data on horsetail to recommend it, so it’s best to skip it during that time.