Benefits, Side Effects, and How to Use It
By Cathy Wong
Updated on October 07, 2022
Medically reviewed by Casey Gallagher, MD
There's no science to back up claims that castor oil is good for hair. Nevertheless, some put this age-old traditional medicine remedy on their scalp to moisturize the skin, reduce dandruff, and improve hair smoothness, strength, and shine. Some say castor oil can help grow eyebrows and eyelashes as well.
Castor oil comes from the castor bean, which is rich in ricinoleic acid—a type of fatty acid known to fight inflammation.1
This article discusses how to use castor oil for your hair and what the purported benefits are. It also covers what to look for when choosing a castor oil product and the possible side effects.
Sol de Zuasnabar Brebbia / Getty Images
The Health Benefits of Castor Oil
Benefits of Castor Oil for Hair
Many claims have been made about the benefits of using castor oil on your hair. However, there is little evidence to back up the anecdotes that say it improves hair health and growth.
Here are a few claims about castor oil and hair growth:
It increases blood flow to the scalp, which promotes healthier hair.
Applying castor oil just once a month can boost hair growth up to five times the usual rate.
It can moisturize a dry, irritated scalp.
Castor oil's antibacterial and antifungal properties can reduce dandruff.
It can help grow hair in other parts of the body, like the eyebrows and eyelashes.
Some people claim that castor oil's benefits for hair are related to its potent antioxidant and anti-inflammatory properties. Antioxidants keep free radicals from damaging the body's healthy cells. This destructive process is called oxidative stress, and it's linked to many health effects, including hair loss.2
Castor oil also contains omega-6 fatty acids—a type of essential fatty acid that may promote hair growth and reduce inflammation in the hair follicle.3
Understanding How Hair Grows
How to Use It
If you’re interested in using castor oil for hair growth, try rubbing just a few drops of the oil into your scalp at first. You can also massage a few more drops into your hair’s midsection and ends to help protect against breakage and improve your hair's texture.
Castor oil is heavy and very sticky, which means it will be hard to remove from your hair. It's best to dilute the castor oil with other natural oils like coconut or jojoba.
Diluting the castor oil can also tone down the scent, which many people find unpleasant. Mix one part of castor oil with two parts of another carrier oil to dilute it.
Many hair care experts recommend using castor oil no more than once a week. Using it more frequently than that can cause buildup and lead to issues like matting.
There are no exact guidelines for how long you should leave castor oil on your hair. That said, know that leaving it in too long can actually dry out your hair and scalp. To prevent drying, wash the castor oil from your hair after about two hours.
Applying Castor Oil to Eyebrows and Eyelashes
If you want to use castor oil on your eyebrows or eyelashes, be very careful not to get any of the oil in your eyes.
Before you put any new product, including castor oil, on your skin, do a patch test. Put a little drop of the oil on your hand or face and wait a few hours to see if it causes any irritation or allergic reaction.
There are a few cosmetic tools that will make the application process easier: a clean eyelash brush or mascara wand and a brow brush.
To apply castor oil to your eyebrows:
Make sure your brow brush is clean. If you don't have a brush you can also use a clean Q-tip.
Wash your face with a gentle cleanser and pat dry.
Pour a small amount of castor oil into a cup or small bowl.
Dip the brush into the oil and let the excess drip off.
Run the brush over each eyebrow to coat the hair. Make sure that the oil is not dripping down into your eyes. The amount of oil you'll need to create a thin layer will depend on how thick your eyebrows are. (You may not need very much if your brows are thin.)
You can decide how long you'd like to leave the castor oil on your lashes. If you do it as part of your morning routine, you might leave it on for a few hours. If you do it before bed, you might choose to leave it overnight.
When it's time to remove the oil, wash your face as you normally do (for example, in the shower or with warm water and a gentle cleanser).
If the skin around your eyes and brows gets irritated, wash the castor oil off right away. If you get the oil in your eyes, don't panic. Flush your eyes with clean water.
To apply castor oil to your eyelashes:
Make sure your lash brush or mascara wand is clean.
Gently cleanse your face and pat dry.
Pour a small amount of castor oil into a cup or dish.
Dip the brush into the oil and let the excess drip off.
Carefully apply to your top and bottom lashes as you would mascara. Be careful not to get any of the oil in your eyes.
There is no hard rule about how long to leave the castor oil on your lashes. If you've used it on your hair before, use that as your guide. Generally, you can leave the oil on for anywhere from a few hours to overnight. Just make sure you wash it off before you put on any cosmetics.
When you're ready to remove the oil, wash your face with warm water and a gentle cleanser.
Best Oils for Every Hair Type
What to Look For
When you're shopping for castor oil, you might see some products that say "cold-pressed" on their labels. Cold-pressed means that the castor seeds were pressed into the oil without the use of heat or harsh chemicals. Many people say that cold-pressed oils are the best quality and more nutrient-rich than those processed with heat.
One of the most popular castor oil products for hair care is Jamaican black castor oil. This variety is made with roasted castor beans and the ash produced by the roasting process. Jamaican black castor oil is said to be especially good for thick, dry, and/or coarse hair.
Does Castor Oil Go Bad?
Castor oil does not last forever. It doesn't "go bad" the same way that perishable food will, but like any oil, castor oil can go rancid. Make sure you know how to store your oil properly.
You'll also need to use it before it reaches the end of its shelf life. Once opened, castor oil will start to go rancid after about one year.
Is Argan Oil Good for Hair?
Side Effects of Using Castor Oil on Hair
There’s some concern that using castor oil as a hair treatment may lead to acute hair felting—a rare disorder in which the hair becomes tangled into a hard mass. Since the condition is irreversible, the only solution is to cut off the affected hair.4
Consuming large amounts of castor oil can also be harmful. While applying castor oil to your hair, it should not cause these side effects. However, you'll want to make sure that you or others in your home do not accidentally swallow the castor oil.
Side effects of ingesting castor oil include:
Abdominal cramps
Diarrhea
Dizziness
Fainting
Hallucinations
Nausea
Shortness of breath and chest pain
Skin rash
Throat tightness5
How Hair Texture Changes With Age
Precautions and Concerns
Castor oil can stain your clothes and towels. Covering your head with a shower cap, an old t-shirt, or a towel until it's time to wash your hair will help prevent the oil from dripping onto your clothes or other items.
Keep in mind that your hair may require two applications of shampoo to completely remove the castor oil.
If you’re thinking of using castor oil as a remedy for hair loss, remember that hair loss can be a sign of an underlying health condition. Before you try treating it at home, talk to your provider if you notice unexplained hair loss.
What Causes Hair Loss?
Summary
Castor oil is popular among natural beauty enthusiasts who claim that applying it to your scalp can boost your hair's health, shine, and growth. There is no scientific evidence to support these claims, although some nutrients in castor oil—like antioxidants and fatty acids—are known to be beneficial for health.
A Word From Verywell
There are many medical conditions that can lead to hair loss, including thyroid disease and alopecia areata. You can also lose noticeable amounts of hair during periods of severe mental or emotional stress. Sometimes hair loss is just a part of getting older.
If you're losing large clumps of hair or you're developing bald spots, talk to your provider before you try using castor oil or any other home remedies. You may have an underlying health condition that needs treatment.
COVID-19 Stress Might Be Causing Uptick in Temporary Hair Loss
FREQUENTLY ASKED QUESTIONS
Does castor oil really help hair growth?
There is no scientific evidence showing that castor oil can promote hair growth. Still, many people claim it works.
How do you use castor oil on your hair?
To use castor oil for hair growth, apply a few drops to your scalp and massage it in. You can also apply castor oil to dry hair as a hair mask. Rub the oil into your hair, then cover your head with a shower cap for around two hours. Wash well with shampoo and style as usual.
How often should I use castor oil on my hair and scalp?
Castor oil should not be used more than once a week. Castor oil is a heavy oil and, if used often, the oil can build up on your hair and make it appear greasy.
Can I leave castor oil in my hair overnight?
You should wash the castor oil out of your hair after about two hours to prevent your scalp from getting too dry.
Does castor oil help your eyebrows grow?
Some people claim that the hair in your eyebrows can benefit from castor oil as the hair on your scalp may. However, there is not much evidence to support the claim.4
Will castor oil make your eyelashes grow?
There is no scientific evidence that castor oil helps eyelashes grow. You should also be careful about using castor oil near you eye; it's not sterile, which means it could cause irritation or infection.6
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