Last Updated on April 25, 2025 by Giorgia Guazzarotti
Can castor oil thicken hair? Mmm…
I love me some castor oil. I mix a few drops with olive oil to make a sleek makeup remover. Takes everything off quickly and leaves my skin super smooth. Sometimes, I use the mixture on my hair, too. It makes it silky soft and super shiny.
Lately, I’ve heard rumours it can thicken hair, too. But I’m afraid this is a feat it can’t pull off… Let’s see what science says:
What Is Castor Oil?
Castor oil’s that thick, sticky oil your grandma probably swore by for everything. Castor oil comes from the seeds of the castor plant (yes, the one with the scary ricin thing, but don’t worry, the oil is totally safe and has nothing to do with Breaking Bad).
It’s packed with something called ricinoleic acid, which is just a fancy way of saying it’s got anti-inflammatory and antibacterial powers. That’s why people love slathering it on their scalp, lashes, brows… you name it. It sounds like the kind of thing that could turn you into Rapunzel overnight… but hold that thought.
Can Castor Oil Thicken Hair?
Here’s the thing: hair thickness is determined by genetics. That’s why it’s so difficult to increase it.
I’ve scoured scientific journal after scientific journal and could find NO evidence that castor oil thickens hair. None. Nada. Niente.
Sorry, ladies! When it comes to hair thickness, you’re still stuck with what you were born with.
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How Did This Myth Originate?
There’s a little kernel of truth in every myth, isn’t there? Castor oil can’t make your hair grow thicker. But it can fool you into believing it made your hair grow thicker. Huh?
Castor oil is sort of like a glue. It’s thick. Once you apply it, it stays put. This alone can make your hair look thicker. Add the small particles of dust the oil attracts and your locks look even thicker.
But… there could be another reason. A lot of people mistake hair thickness for hair density. Hair density is the number of hairs in an area of the scalp.
Castor oil has anti-inflammatory and anti-bacterial properties that can treat follicles infested with bacteria. Once that’s treated, more hair will grow in that area.
One more thing. You usually massage castor oil into your scalp. Massage can stimulate blood circulation, bringing nutrients to your hair faster. It’s another trick that helps your hair grow back faster. Bu you don’t need castor oil for this. The massage alone can do it.
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So What Can Castor Oil Actually Do for Your Hair?
Alright, so it’s not going to turn baby hairs into Beyoncé-level volume overnight. But before you toss it out, it does have a few things going for it. Here are the castor oil benefits for hair:
- Moisturising: It’s a moisture magnet. Castor oil’s packed with ricinoleic acid (fancy name, good vibes). That means it pulls moisture into your strands and seals it in. If your hair’s feeling dry, straw-like, or snappy, this stuff makes it feel soft, smooth, and way more put-together.
- Soothing: It calms a cranky scalp. Got flakes? Itchiness? A scalp that throws tantrums every other day? Castor oil’s anti-inflammatory and antimicrobial properties can help calm things down, especially if dryness is behind it.
- Cleansing: It gives your scalp a reset. Between product buildup, dry shampoo, and whatever else we pile on, your scalp can get a bit… congested. Massaging in a bit of castor oil can help clear that up and give you a cleaner base for new growth to happen. It’s the like attracts like principle in action.
Should You Even Be Using It?
Honestly? If your scalp’s flaky, your ends are breaking, or your hair feels like hay, yes, give it a go. Just a few heads-ups:
- Patch test first. It’s rare, but some people can be sensitive to castor oil. Try a little on your inner arm before diving in scalp-first.
- Go easy. This stuff is thick. Like… molasses thick. You do not need to coat your whole head in it. A few drops will do.
- Mix it with something lighter. Like I said earlier, I like to mix it with olive oil, but jojoba, almond, or argan oil work too. It makes it easier to spread, easier to wash out, and just generally less gloopy.
Which Castor Oil Should You Actually Be Using?
Because yeah, not all castor oils are the same – and some of them are basically the beauty aisle equivalent of a sad salad. Here’s the lowdown:
- Cold-pressed castor oil: This is the good stuff. It’s extracted without heat, so all the nutrients stay intact. Look for one that’s 100% pure and hexane-free. Bonus points if it comes in a dark glass bottle (fancy and functional).
- Jamaican black castor oil (JBCO): Same plant, different vibe. This version’s roasted first, which makes it thicker, darker, and kinda smoky-smelling. People with coarse, curly, or textured hair usually love it because it’s a bit heavier and gives deeper nourishment.
- Refined castor oil: Meh. It’s usually been bleached and deodorized, which sounds about as fun as it is. Most of the good stuff gets stripped out during the process, so unless you’re making DIY soap, you can probably skip this one.
Quick tip: Always read the label. If the ingredient list looks like a chemistry exam, back away slowly. You just want pure castor oil, nothing extra.
The Bottom Line
Hair thickness is determined by genetics. Castor oil won’t affect it. It’ll just give you the illusion of thicker hair.
Nope, never used castor oil on my hair. I’ve used olive oil and coconut oil as hair treatments though! And with your advice, I leave it in overnight. I haven’t done that in a while and perhaps I should.
Janessa, those oils are amazing for hair, aren’t they? They make it so soft and shiny!
I know it can’t thicken hair but sure it did benefited me with hair density and I could see few little hair on my head as i used to massage with mix of oils 🙂
Anubhuti, I’m glad it worked well for you. 🙂
I’m curious about its effects on eyelashes. There are so many good reviews out there claiming it makes them more full and luscious. I just bought a bottle of castor oil and I’m waiting on an empty a mascara tube to add it to my nightly ritual!
Mayette , unfortunately there is no scientific proof yet that castor oil helps eyelashes grow. I think it’s just the viscous texture of the oil that makes them appear thicker and longer.
I have used castor oil on my eyelashes. It does nothing for my length.. but does make my eyelashes more noticeable immediately in some way because it curves them somewhat upwards so instead if sticking out wards from the lid, they go up wards a little and so appear lengthened. it’s ok but nothing like the hype. you can get the same effect with an eyelash curler.
Julina, at least that’s something, isn’t it? If you don’t like using a lash curler, you can always try this. But yeah, nothing like the hype indeed.