DIY Castor Oil For Eyelashes: Natural Growth Serum Recipe

If you’ve spent more than five minutes on TikTok in the last few years, you’ve almost certainly seen it: someone swiping a cotton bud of castor oil along their lash line at bedtime, promising you’ll wake up in six weeks with lashes like a Disney deer.

It’s a lovely idea. Cheap, natural, no needles, no prescriptions.

But before you rush off to coat your eyelashes in oil every night, it’s worth asking the question properly: does castor oil actually make eyelashes grow, or is this one of those beauty myths that just refuses to die?

The honest answer is a bit more nuanced than either the enthusiastic TikTok crowd or the sceptics would have you believe. Let’s get into what’s actually going on, and then I’ll walk you through how to make and use a castor oil lash treatment properly, if you decide it’s worth a try. Along the way I’ll flag a few genuinely surprising bits of biology and chemistry that most beauty content skips over entirely.

I’m Patri Hernández, a certified organic skincare formulator and dermocosmetic technician with a background in health coaching. I work with botanical oils and natural ingredients regularly, and I always look at what the evidence actually shows before recommending anything for use near the eyes.

This post may contain affiliate links. If you buy something through one of them, I may earn a small commission at no extra cost to you. I only ever recommend products I genuinely think are worth considering.

What is castor oil, and why has it become the go-to for lashes?

Castor oil comes from the seeds of the Ricinus communis plant. It’s thick, slightly sticky, and made up of roughly 90 percent ricinoleic acid, a fatty acid found almost nowhere else in nature in such high concentration.

People have been using it on skin and hair for a remarkably long time. Records of castor oil in cosmetic and medicinal use go back to ancient Egypt.

Did you know? The castor bean plant naturally produces ricin, one of the most toxic substances found in nature. Properly processed cosmetic and food-grade castor oil is considered safe for topical use precisely because the ricin protein is removed during pressing and heat treatment. It’s a genuinely handy fact to know if anyone ever tells you castor oil is “dangerous” because of the plant it comes from.

Its recent popularity for lashes really took off through social media, with users reporting longer, thicker-looking lashes after weeks of nightly application. That’s worth paying attention to. It’s also worth being careful with, because anecdote and biology don’t always line up.

A small side note on the name: some historians believe “castor oil” may originally have been named as a cheaper substitute for castoreum, a musky substance once taken from beavers (castor is Latin for beaver) and used in old apothecary remedies. This is a debated bit of etymology rather than settled fact, but it’s a fun one to know regardless. The oil itself, thankfully, has nothing to do with beavers.

Does castor oil actually make eyelashes grow? Here’s what the science says

This is where I have to be straight with you, because a lot of blogs won’t be.

There is currently no clinical trial evidence showing that castor oil stimulates new eyelash growth. A 2024 review of eyelash serum ingredients, published for dermatologists, found that non-prostaglandin ingredients like castor oil lack the kind of formal evidence needed to support growth claims, even though they remain popular.

What does have decent research behind it is castor oil’s effect on the eyelid margin, not the lash follicle itself. A randomised, double-masked pilot study published in Clinical and Experimental Optometry in 2021 found that topical castor oil applied around the eye improved symptoms of blepharitis and meibomian gland dysfunction, two common causes of eyelid irritation. That’s a genuinely useful finding, but it’s a study about eyelid comfort, not lash length.

Separately, ricinoleic acid itself has been shown in laboratory research to have anti-inflammatory and pain-relieving properties, dating back to a frequently cited 2000 study in Mediators of Inflammation. That’s interesting from a formulation perspective, but it doesn’t automatically translate into “grows your lashes.”

There’s also a biological reason why lash serums, castor oil included, can never work the way people imagine. Eyelashes and scalp hair don’t grow the same way at all:

	Scalp hair	Eyelashes
Growth phase (anagen)	Roughly 2 to 6 years	Around 4 to 7 weeks
Resting phase (telogen)	About 3 months	Several months
Maximum length	Can grow very long	Genetically capped at a few millimetres

Here’s the bit most people don’t know: because eyelashes are genetically programmed to stop growing once they reach a set length, no topical product, prescription or natural, can make them grow indefinitely. Even the strongest treatments can only work within a lash’s natural cycle and built-in length limit.

For actual, clinically proven eyelash growth, the only FDA-approved option is bimatoprost, sold under the brand name Latisse, which works through an entirely different pathway involving prostaglandin receptors in the hair follicle. It comes with its own documented side effects, including permanent changes to iris colour and loss of fat around the eyes in some users, which is exactly why it requires a prescription.

So no, castor oil isn’t a proven “growth serum” in the clinical sense. I want to say that plainly, because a lot of content online blurs that line, and you deserve accurate information before you put anything near your eyes.

What castor oil can realistically do for your lashes

None of this means castor oil is useless. It just means we should talk about what it actually does, rather than what the hashtags promise.

Fun bit of biology first: eyelashes aren’t purely decorative. They work rather like a cat’s whiskers, acting as a sensory trigger that sets off your blink reflex the instant something like dust, an eyelash mite, or a stray insect gets too close. That reflex is one of your eye’s main defences, which is part of why keeping the lash line healthy matters beyond appearances.

• Conditions existing lashes. Castor oil is an occlusive oil, meaning it sits on the hair shaft and slows moisture loss, which can leave lashes feeling softer and looking glossier.
• May reduce breakage. A well-conditioned lash is less likely to snap off partway through its growth cycle, which over time can make your lash line look fuller simply because you’re not losing hairs early.
• Soothes the lash line. Given the blepharitis research above, there’s a reasonable case that gentle castor oil use around (not in) the eye may support a calmer, less irritated eyelid margin.
• Feels nourishing during makeup removal. Its texture makes it a pleasant addition to an evening skincare routine, even if the “growth” claim doesn’t hold up.

Quick fact: the average adult has somewhere between 90 and 160 lashes on the upper lid and around 70 to 80 on the lower lid. Losing a handful each day is completely normal; every single lash is constantly cycling through its own private growth and shedding schedule, independent of the ones next to it.

Think of castor oil less as a growth serum and more as a conditioning treatment that protects the lashes you already have. That’s a genuinely reasonable, low-risk thing to want.

What you’ll need

• Cold-pressed, hexane-free castor oil
• A few drops of vitamin E oil (optional, but useful as a natural antioxidant to help slow oxidation)
• A clean 2 oz dropper bottle for mixing and storing your blend
• A clean, disposable mascara wand or a small angled brush for application

Formulator’s note: vitamin E isn’t just a nice extra ingredient for the label. It’s a genuine antioxidant that helps slow the natural oxidation, or rancidity, of carrier oils over time. That matters more than people realise for a product that’s going to sit in a bottle on your shelf for weeks.

Choosing the right type of castor oil

You’ll often see Jamaican black castor oil recommended for hair growth, and it does have a loyal following for scalp use. It’s roasted and has a higher pH, which is part of why some people find it effective on the scalp.

For the delicate eye area, though, I’d steer you towards a plain, cold-pressed, hexane-free castor oil instead. It’s gentler, clearer, and less likely to cause irritation on skin as thin and sensitive as your eyelid.

Texture aside: castor oil is one of the most viscous plant oils used in cosmetics, noticeably thicker than something like jojoba or almond oil. That thickness is exactly why it clings to the lash line instead of running straight into your eye, and also exactly why a little goes such a long way.

How to make and use a castor oil eyelash serum

1. Patch test first. Apply a small amount of castor oil to the inside of your forearm and wait 24 to 48 hours. If there’s no redness, itching, or irritation, it’s reasonably safe to move on to your lash line.
2. Mix your blend. Fill your dropper bottle with castor oil, then add three to four drops of vitamin E oil per 30ml. Shake gently to combine.
3. Cleanse your face. Remove all makeup and cleanse thoroughly. Any residue left on the lashes can trap the oil against the skin and increase the chance of irritation.
4. Apply sparingly. Dip a clean mascara wand or small brush into the oil, wipe off any excess, and draw it lightly along the base of your top lashes, the way you’d apply eyeliner. A little goes a long way here.
5. Avoid the waterline. Keep the oil on the lash itself, not directly in the eye. If oil does get into your eye, it can cause temporary blurred vision or stinging; flush with clean water if that happens.
6. Leave it on overnight. Let the oil work while you sleep, then cleanse it off in the morning before applying makeup.

Worth knowing: eye care professionals generally recommend replacing mascara wands roughly every three months because bacteria can build up on them surprisingly quickly with regular use. That’s exactly why reusing an old, unwashed wand for an overnight eye treatment isn’t a great idea, however tempting it is to grab whatever’s already in your makeup bag.

How often, and how long before you notice anything

Nightly use is standard for this kind of treatment. Because eyelashes go through their own natural growth cycle, typically shedding and regrowing over several weeks, it’s worth giving any lash routine at least four to six weeks before deciding whether you like the results.

Given everything we’ve covered above, be realistic about what “results” means here. You may notice softer, glossier, less brittle lashes. You are unlikely to see the dramatic length increase associated with prescription treatments, and that’s simply down to the different way they work, not a failure on your part.

Common mistakes to avoid

• Using too much oil. Excess product is more likely to migrate into the eye overnight and cause irritation.
• Choosing Jamaican black castor oil for the eye area. Save that one for your scalp; it’s more alkaline and better suited to hair growth applications than the sensitive periorbital skin.
• Skipping the patch test. Allergic reactions to castor oil are uncommon but do happen, and the eye area is not where you want to discover one.
• Applying with a dirty wand. Reusing an old mascara wand without cleaning it introduces bacteria right at your lash line.
• Not removing it before makeup. Oil left on the lashes can make mascara slide and clump.

Safety considerations

Always keep oil away from the actual eyeball, not just the lash line. If it gets in, rinse with clean water immediately.

Discontinue use and speak to a doctor or dermatologist if you notice redness, swelling, crusting, or persistent itching at the lash line. These can be signs of an allergic reaction or an underlying condition such as blepharitis, which needs proper treatment rather than more oil.

If you wear contact lenses, apply the oil carefully and avoid contact with the lenses.

Bold fact worth knowing: castor oil has a long history of oral use as a strong laxative and, in folklore, as a way to try to induce labour. That’s about drinking it, not the tiny topical amount used on lashes, but it’s part of why some people associate castor oil with pregnancy caution more broadly. If you’re pregnant or breastfeeding and unsure, a quick check with your doctor is a sensible extra step, purely for peace of mind.

If your lash loss is sudden, patchy, one-sided, or accompanied by inflammation, that’s a pattern worth having checked by a professional rather than treating cosmetically. It can point to something like an autoimmune condition, a fungal issue, or habitual lash pulling, none of which respond to oil.

For storage, keep your castor oil blend in a cool, dark place, away from direct sunlight. Cold-pressed castor oil is reasonably shelf-stable, but the vitamin E addition helps slow oxidation once the bottle is opened. If the oil starts to smell off or turns cloudy, discard it.

What about eyelash growth serums that actually have evidence behind them?

If genuine, measurable lash growth is your goal, it’s worth knowing what the current evidence-based landscape looks like. Bimatoprost (Latisse) remains the only FDA-approved option, backed by proper clinical trials, though it requires a prescription and carries a real risk of permanent iris darkening and fat loss around the eyes in some users.

Over-the-counter serums containing peptides, rather than prostaglandins, are a newer category with some promising early data, though nowhere near the volume of research behind bimatoprost.

Castor oil sits in a different category altogether. It’s not trying to compete with prescription treatments; it’s a gentle, low-cost, traditional conditioning oil, and it’s most honestly marketed as exactly that.

FAQ

Can castor oil make my eyelashes fall out?
Used correctly and after a proper patch test, this is unlikely. Irritation from overuse or an allergic reaction could contribute to shedding indirectly, which is why patch testing and using a small amount matter.

Is Jamaican black castor oil better for lashes than regular castor oil?
Not for this particular use. It’s a wonderful oil for the scalp, but its higher alkalinity makes plain, cold-pressed castor oil the gentler choice for the eye area.

How long until I see a difference?
Give it four to six weeks of consistent nightly use before judging results, and keep your expectations focused on conditioning rather than dramatic growth.

Can I use castor oil with eyelash extensions?
Oil-based products can weaken the adhesive used for lash extensions, so it’s best avoided unless your lash technician says otherwise.

Can I mix castor oil with other oils, like jojoba or almond?
You can, and some people prefer a lighter blend since castor oil is quite viscous on its own. Just introduce any new oil one at a time so you know exactly what’s causing a reaction if one occurs.

Is it safe to use every night indefinitely?
For most people, yes, assuming no irritation develops. If you ever notice ongoing redness or discomfort, stop and reassess.

Final thoughts

Castor oil isn’t the miracle growth serum that a lot of beauty content makes it out to be, and I’d rather tell you that honestly than let you expect a Latisse-level transformation from a kitchen cupboard ingredient. What it can genuinely offer is a simple, low-cost way to condition and protect the lashes you already have, rooted in a plant with a very long history of skin and hair use, and a surprising amount of interesting biology behind it.

Used sensibly, with a proper patch test and a light hand, it’s a pleasant addition to an evening routine. Just go in with realistic expectations, and keep an eye out for anything that suggests you need a dermatologist or ophthalmologist rather than another dropper bottle.

References

• Muntz, A., Lacey, M., & Craig, J. P. (2021). Topical periocular castor oil for blepharitis and meibomian gland dysfunction: A randomised, double-masked, pilot study. Clinical and Experimental Optometry
• Vieira, C., Evangelista, S., Cirillo, R., Lippi, A., Maggi, C. A., & Manzini, S. (2000). Effect of ricinoleic acid in acute and subchronic experimental models of inflammation. Mediators of Inflammation
• Eyelash serums: A comprehensive review. PubMed
• American Academy of Ophthalmology: What you should know about eyelash growth serums

Love, Patri xx