Castor oil comes from the beans of the castor tree. It’s an ingredient in many cosmetics and has been used throughout history to treat many different ailments.

It’s most well-known use is as an oral laxative, but it’s also been used to:

  • induce labor
  • heal fungal and bacterial infections
  • soothe sunburn
  • treat dandruff
  • heal hemorrhoids
  • moisturize skin

Castor oil’s reputation as a potential treatment for hair loss has led to people using it as a way to grow thicker, more lustrous eyebrows and eyelashes. Does it work?

How to use castor oil on eyebrows

There are two main types of castor oil to choose from for eyebrow application: clear or cold-pressed castor oil and Jamaican black castor oil, which is pressed from roasted castor seeds.

Both types contain the same properties that may help hair grow thicker.

It’s important to choose a product that is pure castor oil. Castor oil that has been blended with other oils or additives may cause irritation and not produce desired results.

Before you apply castor oil to your eyebrows, do a patch test to make sure you won’t have an allergic reaction. To do a patch test: Apply a few drops of castor oil on the underside of your arm. Wait at least a day to see if the area develops symptoms of an allergy, such as redness, swelling, and itchiness.

If you don’t develop any allergic reactions, you can proceed with using it on your face.

To apply castor oil to the eyebrows:

  1. Pick a time of day to apply castor oil to the eyebrows on a daily basis. At night, before bed, is a good choice so that the thick oil can remain on the brows while you sleep. You may want to protect your pillowcase with a towel.
  2. Make sure your eyebrows are clean and free of makeup.
  3. Use a cotton swab or clean mascara wand to wipe a small amount of castor oil over the eyebrows.
  4. Gently massage the castor oil into the eyebrows. Take special care to not allow any castor oil to come into contact with the eyes. If it does, wash it out immediately.
  5. Wash the castor oil off in the morning with water or a mild cleanser.

Because there isn’t a lot of research about this remedy, it’s difficult to know how long you need to use it before you’ll see results.

Is there research to support using castor oil on your eyebrows?

There are currently no published studies that test how castor oil affects eyebrow growth.

However, there is evidence that ricinoleic acid — a chemical compound that makes up almost 90 percent of castor oil — may treat hair loss:

  • In one study, researchers found that men who have lost hair as a result of male pattern baldness have high amounts of the protein prostaglandin D2 (PGD2).
  • In another study, researchers found that ricinoleic acid may inhibit PGD2, helping the participants of the study grow their hair back.

More research needs to be done to determine if ricinoleic acid can help grow hair back in other cases.

What to know before you try this remedy

It’s important to patch test castor oil before you apply it to your eyebrows to make sure you won’t have an allergic reaction.

If you see any sign that you are having a negative reaction to castor oil, you should discontinue use immediately. Consult a dermatologist if the reaction doesn’t get better several days after you have discontinued the castor oil.

Pregnant or lactating women should not use castor oil, as it does get absorbed by the body and is used medically to induce labor.

Avoid getting castor oil into the eyes, as it can be extremely irritating. If you do get castor oil in your eyes, flush them immediately with water.

The bottom line

Castor oil is a safe, affordable, natural home remedy that has been used for years to treat a variety of conditions, including hair loss.

While there haven’t been scientific studies that prove that castor oil can regrow hair, it’s a low-risk remedy that may help you get thicker eyebrows.