The thick, old-fashioned oil that social media says can do everything. What it really does, what the research shows for hair and lashes, the risks worth knowing, and what 8 skincare experts said about it on camera.
Castor oil is having a moment. Depending on which video you watch, it will thicken your lashes, regrow your hair, smooth your wrinkles and clear your skin. Can one thick, old-fashioned oil really do all that? And is there any harm in trying?
The honest answer: castor oil is a good, thick sealing oil, and that is about where the evidence stops. The research does not back the claims that it grows hair or lashes, and the experts are split on how much of the hype it deserves.
That split is why castor oil's Guru Score is 62%. The fans use it as a sealing oil at the end of a night routine, on cuticles and dry patches, and along the lash line. The doubters, mostly dermatologists, say the hair and lash growth claims run well ahead of the evidence. Below, what the experts said sits next to what the studies found, and on this topic the studies are thin.
Castor oil is a thick plant oil used to soften and seal in moisture on dry skin, lips, cuticles, brows and lashes. The experts we track are divided. The research does not back the popular claim that it grows hair or lashes: a systematic review found weak evidence that it adds shine to hair and no strong evidence that it helps hair grow [2]. It is generally well tolerated on skin, but allergic reactions happen [1, 6].
| Question | What we found |
|---|---|
| What is it used for? | Softening and sealing in moisture on dry skin, lips and cuticles, and coating brows and lashes. |
| Do skincare experts recommend it? | They are divided. Fans love it as a sealing oil, and the doubters say the growth claims are unproven. |
| Does it grow hair or lashes? | Not as far as the research shows. A systematic review found no strong evidence it helps hair grow [2]. |
| What is in it? | Mostly ricinoleic acid, which makes up about 90% of its fatty acids [1]. |
| Is it safe on skin? | Generally, yes. Safety reviewers found it rarely irritates or sensitises skin in human tests, though allergies do happen [6, 7]. |
| Any rare risks? | On long hair it has been linked to sudden, irreversible matting, known as acute hair felting [3]. |
Castor oil is pressed from the seeds of the castor plant, Ricinus communis. It is unusually thick and sticky for a plant oil, and about 90% of its fatty acids are one called ricinoleic acid [1]. That makes it quite unlike lighter oils such as squalane.
In cosmetics it works as a skin conditioning ingredient, and it is a long-standing base for lip products: a safety review recorded it at concentrations of up to 81% in lipstick [6]. On skin, its thickness is the point. It sits on the surface, softens, and slows moisture escaping, which is why the experts who like it use it as the last step of a routine.
You will hear a lot of bigger claims: that it grows hair and lashes, smooths wrinkles, clears acne and calms inflammation. Most of that rests on anecdote or on lab and animal work rather than human trials, as one recent review puts it plainly [1]. Dr Dray makes the same point on camera: it is an emollient, and nobody has shown it is a more magical one than any other.
Here is what each of them said on camera, with a link to the moment they said it.
The best facial oil is going to shock you. Castor oil. I discovered this a year and a half ago. I didn't believe in it. I thought it was all hype. I now have gotten rid of all my facial oils and I just use a few drops of this to seal the deal in the evening. Perfect for your winter skincare routine.Watch ▸
Around 12 to 18 months ago, I started out as a firm skeptic. Someone that thought there was just too much hype around castor oil. [...] However, the FOMO crept in. I tried it out and I've been so so surprised. I would definitely recommend everyone try out castor oil in their own skincare routine, work out how it could benefit them.Watch ▸
This ingredient is actually a common remedy used to treat dry eyes so it can be applied safely to the eyelids and the lash line at night to protect the tear film of the eye. It is also thought to improve blood flow to the eye which can help with lash growth and the health of your lashes.Watch ▸
I want to caution you though: castor oil is not a treatment for any skin disease, and there's no research truly on castor oil for correcting any kind of skin problem. [...] It's an emollient, right? But is it any more magical than any other emollient at this point in time? Scientifically speaking, we don't really know in terms of how it performs in the skin.Watch ▸
Castor oil is something that has traditionally been used in a lot of cultures to aid in hair softening and hair growth, but there are no scientific studies that show that it actually improves hair growth or eyelash growth. As an oil it can make a nice coating on the hair that can maybe improve the luster of the hair a little bitWatch ▸
I have a vendetta against Castor Oil and it's that it doesn't do much of anything and people say it does absolutely everything. [...] There's really almost no study backing of why Castor Oil would do any [...] of those things, and that's why I'm particularly frazzled when it comes to Castor Oil because it very much overpromises.Watch ▸
This is a real split, and the caveats are where the useful detail sits.
Not as much as its popularity suggests. A 2026 review of castor oil in dermatology found some small studies, mostly of castor oil inside formulas, but concluded that much of its use is supported by anecdote or extrapolated from lab findings, and called for proper trials [1].
There is no good evidence that it does. A 2022 systematic review of hair oils found weaker evidence for castor oil than for coconut oil, with some support for castor oil adding shine to hair and no strong evidence that it helps hair grow [2].
The theory you will hear involves prostaglandins. Lab work suggests ricinoleic acid may block an enzyme that makes prostaglandin D2, a substance found in higher amounts on scalps with pattern hair loss [1]. But a trial of a drug that blocks the prostaglandin D2 pathway did not help men with pattern hair loss, so whether that pathway matters in practice is uncertain [1]. Ricinoleic acid does act on one prostaglandin receptor in the gut and the womb, which is how castor oil works as a laxative [8]. No study has shown it does anything similar in a hair follicle.
We found no trial showing castor oil grows lashes or brows. Dr Dray and Dr. Sam Ellis both suggest the fuller look people notice comes from the oil coating each hair, and Dr. Sam Ellis says it may soften brittle lashes, which could mean fewer break. That is a reasonable idea, not a tested result.
Where castor oil does have some evidence near the eyes is blepharitis, an inflammation of the eyelid margins. In a small trial, 26 people applied cold-pressed castor oil to the lids of one eye twice a day for four weeks. That eye improved on symptoms and on signs such as thickened lid edges and matted lashes, with no adverse events [4]. A review describes castor oil helping the oily layer of the tear film and calls it safe and well tolerated on the eye surface [5]. If sore, crusty lids are holding your lashes back, that may help indirectly.
Possibly, but the evidence is in animals. In mice and guinea pigs, repeated application of ricinoleic acid reduced experimental swelling, although a single application increased it at first [10]. That does not tell you what a few drops do to inflamed skin on your face.
A safety review found castor oil was not a significant irritant or sensitiser in human tests, though people with existing skin conditions can react [6]. Allergies do turn up in case reports, including one in a teenager whose lip balm caused allergic contact cheilitis, an itchy inflammation of the lips [7]. Ricinoleic acid looks like the likely trigger, since some people react to plain castor oil but not to its hydrogenated form [1].
The rarest risk is to long hair. Acute hair felting is a sudden matting of the hair into a hard mass that cannot be untangled. One case report describes a patient's whole scalp of long hair felting straight after an oil bath with coconut and castor oil, and the hair had to be cut off [3]. The authors put it down to castor oil's thickness combined with long hair.
This is where most of the online claims live, and where the experts and the research line up most closely. Dr. Sam Ellis says no scientific studies show castor oil improves hair or eyelash growth, and Doctorly say there is almost no study backing for what it is said to do. Dr Dray says there is no research behind the hair growth claims, though she calls it pretty benign and thinks it may cut down on breakage.
The Budget Dermatologist is more positive about lashes. She describes castor oil as a common remedy for dry eyes that can be applied to the lash line at night, and says it is thought to improve blood flow to the eye. The first part fits the eye research [4, 5]. We found no study showing castor oil improves blood flow around the lashes, and the eye review we read lists it as vasoconstrictive, which would point the other way [5].
A castor oil pack is a cloth soaked in castor oil and laid on the skin, often with heat. Nipun Kapur uses one on her face and is a big fan. Packs are widely promoted for detox, digestion and more, but we found very little research on them. The one trial we found tested packs on the abdomens of older people with long-term constipation: stools were softer and there was less straining, but no more bowel movements [11]. We found no studies of packs for skin, wrinkles or anything else.
Castor oil taken by mouth is a strong laxative, and its ricinoleic acid also makes the womb contract [8]. This guide is only about putting it on your skin and hair.
Because it is so thick, a little goes a long way. The experts who use it on their faces use a few drops at most.
Beyond50Skin lets the rest of her skincare dry down, then presses in a few drops of castor oil to seal it in overnight. If your skin is dry, that is the most sensible use: the last step, in a thin layer.
Castor oil is a classic lip product base [6], and Dr Dray explains that it can soften lips and help reduce water loss. Beyond50Skin uses it on her cuticles, hands and heels. Stop if your lips get itchy, red or flaky, since castor oil is a known cause of lip allergy [7].
Sincerely Miss Ash mixes a drop or two of castor oil into her cleanser in winter and finds it leaves her skin with a moisture layer rather than greasy. We found no studies of castor oil for oil cleansing, so this one is down to experience.
If you use it on your lashes, apply a tiny amount to the lash line with a clean brush and keep it out of your eyes. Stop if your eyes or lids become red, itchy or swollen. If you have a lash line problem such as blepharitis, ask an optometrist or doctor first.
A small amount on the ends can add shine [2]. Be careful with long hair: use a little, mix it with a lighter oil, and never pile a large amount onto long, tangled hair, since that is the setting in which acute hair felting has been reported [3]. Dr Dray also warns that heavy castor oil hair products near the hairline can trigger breakouts.
Some of our experts say castor oil has helped their acne; others are doubtful. We found no human trial of castor oil for acne. If you break out easily, try it on one small area for a couple of weeks first.
Castor oil is not an active ingredient and does not exfoliate, so it rarely clashes with anything. Think of it as a top coat.
Hyaluronic acid draws water into the skin, and a thick oil on top helps keep it there. Apply hyaluronic acid on damp skin, then moisturiser, then a drop or two of castor oil.
A thin layer of oil over a moisturiser can make a retinoid routine feel more comfortable on dry skin. Castor oil adds no exfoliation of its own. Bring the retinoid in slowly, whatever you pair it with.
Because it is so sticky, plenty of people mix castor oil with a lighter oil such as squalane or jojoba, on the face and on hair. Doctorly say they would rather see people use squalane than castor oil for dry skin.
Not as far as the research shows. We found no trial showing castor oil makes lashes grow. Dr. Sam Ellis says no scientific studies show it improves eyelash growth, though it may soften brittle lashes, and Dr Dray thinks the fuller look comes from the oil coating each lash. A small trial did find it helped blepharitis, a lid inflammation that can affect lashes [4].
There is no strong evidence that it does. A systematic review of hair oils found some support for castor oil adding shine to hair, but no strong evidence that it helps hair grow [2]. A lab theory involving prostaglandin D2 exists, but a drug that blocks that pathway did not help men with pattern hair loss in a trial [1]. For hair loss, see a dermatologist about treatments with evidence behind them.
It can be a good sealing oil for dry skin, but it is not a treatment. Fans such as Beyond50Skin use a few drops at night as the last step. Dr Dray points out there is no research showing it is better than any other emollient, and Doctorly think it overpromises. The experts we track are divided on it.
We found no good human study either way. Some of our experts say castor oil has never broken them out, while Dr Dray warns that heavy castor oil hair products near the hairline can trigger breakouts. Because it is so thick, start with a drop on one small area for a couple of weeks if your skin is acne-prone, and stop if new bumps appear.
Yes, though it is uncommon. A safety review found castor oil was not a significant irritant or sensitiser in human tests [6], but case reports describe allergic reactions, including inflamed, itchy lips from a lip balm [7]. Ricinoleic acid appears to be the trigger [1]. Patch test on your inner arm first, and stop if you see redness, itching or swelling.
Used carefully, it appears to be. In a small trial, people applied cold-pressed castor oil to their eyelids twice a day for four weeks with no adverse events [4], and a review calls it safe and well tolerated on the eye surface [5]. Use a tiny amount on the lash line, keep it out of the eye itself, and stop if your eyes or lids become irritated.
Rarely, but it has happened. A case report describes a patient's long hair matting into a hard, tangled mass immediately after an oil bath with coconut and castor oil, a condition called acute hair felting [3]. It could not be undone and the hair had to be cut off. The authors blamed castor oil's thickness and the length of the hair, so use only a little on long hair.
There is very little research on them. The one trial we found used castor oil packs on the abdomen in older people with long-term constipation: stools were softer and there was less straining, but no more bowel movements [11]. We found no studies of castor oil packs for detox, skin, wrinkles or anything else, so those claims are unproven.
It is a classic lip product ingredient. A safety review recorded it at up to 81% of some lipsticks [6], and Dr Dray explains that it can soften lips and help reduce water loss. It is also a known cause of lip allergy in some people [7], so stop using it if your lips become itchier, redder or flakier rather than softer.
They feel very different. Squalane is light and absorbs quickly, while castor oil is thick and sits on the surface, which some people like as a final seal at night. Doctorly would rather see people use squalane than castor oil for dry skin. If you find castor oil too sticky, many people mix the two.
Many of our experts who like it do. Beyond50Skin uses a few drops every evening, and Sincerely Miss Ash adds a drop to her cleanser morning and night in winter. A safety review judged castor oil safe as used in cosmetics [6]. Keep the amount small, and stop if you notice irritation, itching or breakouts.
Ask your doctor or midwife first. We found no research on putting castor oil on the skin in pregnancy. Taken by mouth, castor oil has been used to try to bring on labour: its ricinoleic acid makes the womb contract [8], and in a Cochrane review every woman who drank it felt sick [9]. Never take it by mouth while pregnant unless your midwife or doctor advises it.
8 experts, 29 mentions, every one traced to a video you can watch. Sponsored takes are excluded.
This guide combines two kinds of information. The expert consensus comes from 29 mentions of castor oil by 8 skincare experts in their YouTube videos. Each one was read, given a Yay, Mixed or Nay verdict and linked to the moment it was said. Sponsored takes are excluded. The research sections summarise published studies, a cosmetic safety review and medical sources, listed in full above.
The Guru Score measures how warmly the experts talk about castor oil. It is not a measure of clinical effectiveness, and this guide is not medical advice. It has not been reviewed by a doctor.
This guide is general information, not medical advice. The Guru Score reflects how warmly the experts we track talk about castor oil; it is not a measure of clinical efficacy. Speak to a dermatologist or doctor about a diagnosed skin condition, and before using any medicine.
Nipun Kapur
Sincerely Miss Ash