Eyelash Growth: Castor Oil vs Careprost and the Real Risks
Careprost is a glaucoma eye drop. That single fact gets buried under Instagram ads selling it as a lash serum, and it is the most important thing to know before you put a drop of it anywhere near your eyes for cosmetic reasons.
Before you start
- Castor oil: traditional, low-risk, no strong evidence it grows lashes, but conditions existing ones.
- Careprost / bimatoprost: a prescription glaucoma medicine, not an approved over-the-counter cosmetic in most places it is sold that way.
- Not rubbing your eyes: genuinely protects existing lashes from breaking off early.
- Realistic timeline: a full lash growth cycle takes roughly 6 to 8 weeks.
Prefer to listen? This post as a 5 min video · Watch the video
What castor oil can and cannot do
Castor oil is thick, rich in ricinoleic acid, and coats the lash shaft, which can make lashes look glossier and feel less brittle almost immediately. What it has not been shown to do, despite the popularity of the totka, is speed up how fast new lashes grow or make hair sprout from follicles that are not currently growing. If your lashes look fuller after weeks of castor oil use, the more likely explanation is that existing lashes are breaking less and looking healthier, not that dozens of new lashes suddenly appeared.
- Wash your face and remove all eye makeup thoroughly before applying.
- Dip a clean, dry spoolie or cotton bud into castor oil, wiping off excess so it is not dripping.
- Apply along the base of the upper lash line only, avoiding direct contact with the eye itself.
- Leave overnight and rinse off gently in the morning with plain water.
- Use nightly for at least 6 to 8 weeks before judging whether it made a visible difference.
False lashes, extensions and lash lifts
Strip lashes glued daily, or lash extensions applied and removed roughly every three to four weeks, both put mechanical stress on the natural lash line, and improper removal, pulling extensions off rather than having them professionally dissolved, is a common cause of sudden, patchy lash loss. A lash lift, which curls existing lashes using a chemical process similar to a perm, does not add length but can make lashes look longer by changing their angle; it carries its own small risk of irritation if the chemical sits too long or touches the eye directly, so it should only be done by someone experienced and never attempted as a home experiment.
Where careprost fits, and where it does not
Careprost’s active ingredient, bimatoprost, is a genuine prescription medicine developed to lower eye pressure in glaucoma, and lash growth was noticed as a side effect in people using it for that purpose. That side effect became a marketed cosmetic product in some markets, sold without the prescription and medical supervision that the original medicine requires. This matters because bimatoprost is not a harmless cosmetic oil: it can cause eye irritation, redness, unwanted darkening of the eyelid skin, and in some users has been linked to changes in eye colour, particularly in lighter eyes, which can be permanent. It should never be bought and used without a doctor’s involvement, and buying it from unregulated online sellers adds the further risk of a product that is not what the label claims.
| Option | Evidence | Main risk |
|---|---|---|
| Castor oil | Traditional, conditions lashes, weak evidence for growth | Low, occasional allergy |
| Careprost/bimatoprost | Genuine growth effect, studied for glaucoma use | Eye irritation, pigment changes, needs medical supervision |
| Not rubbing eyes | Reduces lash breakage | None |
What eyelash growth serums with less controversial ingredients contain
Some commercial lash serums use peptides or panthenol-based conditioning ingredients rather than bimatoprost, aiming for a gentler conditioning effect similar in spirit to castor oil, with generally lower risk of eye irritation or pigment change than a bimatoprost-based product. These are a reasonable middle option for someone who wants more than plain oil but is not comfortable with a prescription-strength ingredient used off-label. Read the ingredient list before buying, since some products marketed simply as “lash serum” do quietly contain bimatoprost or a close relative without stating it clearly on the front label.
The simplest fix nobody markets: stop rubbing your eyes
Rubbing tired or itchy eyes pulls on lashes at the root and is one of the most common, least discussed reasons lashes look sparse over time, particularly for people who rub their eyes out of habit while reading a phone screen or after removing contact lenses. Reducing that single habit, alongside gently removing eye makeup rather than scrubbing it off, protects the lashes you already have far more reliably than any serum promises to grow new ones.
Nutrition and general health play a background role too
Lashes, like nails and hair, grow from follicles that depend on adequate overall nutrition, and a body under significant nutritional stress, from crash dieting, illness, or a genuine deficiency, can shed hair and lashes faster than normal as a low-priority system the body deprioritises first. This is rarely the main story behind ordinary sparse lashes, but it is worth a thought if lash thinning appears suddenly alongside other signs like hair loss elsewhere or unusual tiredness, since that combination points toward something systemic rather than a simple cosmetic fix.
Myth: mascara wands with old brushes help lashes grow
Reusing old mascara wands as a “lash serum brush” is a popular trick, but the brush itself does nothing for growth. It is only useful as an applicator, and an old, unwashed brush actually raises the risk of eye infection from bacteria that build up in mascara tubes over time.
Castor oil applied to lashes and brows overnight is a genuinely old household habit across South Asian homes, generally understood as nourishing and conditioning rather than as a growth stimulant, which lines up reasonably well with what is actually known about it today.
Try this
If lash breakage is your real complaint, switch to a gentle, oil-based makeup remover instead of scrubbing with a dry wipe, and see if lashes look noticeably fuller within a few weeks purely from that one small change in your evening routine.
Never apply castor oil or any lash product if you have an active eye infection, recent eye surgery, or known allergy to castor oil. Careprost and any bimatoprost-based lash product should only be used under a doctor’s guidance, never bought casually online for cosmetic use, and never used by anyone with glaucoma, a history of eye inflammation, or during pregnancy or breastfeeding without medical advice. Stop any lash product immediately and see a doctor if you notice eye pain, vision changes, unusual redness that does not settle, or eyelid skin darkening you did not expect.
For another simple, oil-based beauty routine with a similar low-risk profile, see our guide on homemade lip balm with exact ratios. More practical, safety-checked beauty guides live under Desi Remedies.
Castor oil and lash serum questions
Does castor oil really grow eyelashes?
There’s no good evidence that it makes new lashes grow or speeds up growth. What it does is coat and condition the lashes you have, so they look glossier and break less. That’s often why lashes seem fuller after a few weeks.
How do I apply castor oil to my eyelashes?
Remove all eye makeup, dip a clean spoolie or cotton bud in castor oil and wipe off the excess, then run it along the base of the upper lashes only. Keep it out of the eye itself. Leave it overnight and rinse with plain water in the morning.
How long does it take to see results on eyelashes?
Give any routine at least 6 to 8 weeks, which is roughly one full lash growth cycle. Castor oil’s glossy look shows almost straight away, but any change in how full your lashes look needs the full cycle to judge fairly.
Is careprost safe for eyelash growth?
Careprost is bimatoprost, a prescription glaucoma medicine, not a cosmetic. It can cause eye irritation, redness, darkening of the eyelid skin and, in some people, a permanent change in eye colour. It should only be used with a doctor’s involvement.
Can I buy careprost without a prescription safely?
No. Unregulated online sellers can’t guarantee what’s in the bottle, and using it unsupervised means nobody is watching for irritation or pigment changes. If you’re considering it, talk to an eye doctor first.
Can eyelash serums change my eye colour permanently?
Bimatoprost-based products have been linked to darkening of the iris in some users, particularly with light-coloured eyes and long or unsupervised use, and the change can be permanent. Check the ingredient list, since some serums contain bimatoprost without saying so on the front.
Is castor oil safe to use near the eyes?
For most people it’s low risk when applied to the lash line and kept out of the eye. Don’t use it with an eye infection, after recent eye surgery or if you’re allergic to it. If it gets in the eye, rinse with clean water.
Can I use careprost or lash serum during pregnancy?
Avoid bimatoprost-based lash products while pregnant or breastfeeding unless a doctor has advised otherwise. Plain castor oil on the lash line is the lower-risk choice if you want something during this time.
Why are my eyelashes falling out?
Common reasons are rubbing your eyes, scrubbing off makeup, and pulling off extensions or strip lashes. Sudden thinning along with hair loss elsewhere or unusual tiredness can point to something wider, such as a nutritional gap or thyroid issue, and is worth a doctor’s check.
Are eyelash extensions and false lashes bad for natural lashes?
They put strain on the lash line, and daily glue or pulling extensions off can cause patchy loss. Have extensions removed professionally, use good-quality glue, and give your lashes regular breaks between sets.
Does mixing castor oil with coconut or almond oil work better?
Mixing mainly thins castor oil so it’s easier to apply. It doesn’t make it grow lashes any better. Use whatever texture you find comfortable.
When should I stop a lash product and see a doctor?
Stop straight away if you get eye pain, changes in vision, redness that doesn’t settle, or unexpected darkening of the eyelid skin. Those need an eye doctor’s look, not another product.