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.
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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.
Can I buy careprost without a prescription safely?
No. It is a prescription medicine, originally a glaucoma treatment, and it should only be used with a doctor’s involvement. Unregulated online sellers cannot guarantee what is actually in the bottle, and using it without medical supervision means no one is checking for the eye irritation or pigment changes it can cause.
Does castor oil work faster mixed with other oils?
Mixing castor oil with almond or coconut oil mainly changes the texture, making it less thick and easier to apply. It does not meaningfully change growth potential.
Is it safe to use false eyelash glue every day?
Daily use of lash glue, especially poor-quality glue, can weaken the natural lash line over time. Giving lashes regular breaks from extensions or strip lashes helps.
Can eyelash growth serums cause permanent eye colour change?
Bimatoprost-based products have been linked to darkening of the iris in some users, particularly with long-term or unsupervised use, and this change can be permanent. This is a genuine reason to only use such products under medical guidance.