What Makes Eyelashes Grow?

Eyelashes grow because of the hair follicles along your eyelid margin, and each lash follows the same growth cycle as the hair on your scalp. Cells in the follicle divide, push upward, and harden into the visible lash. Genetics set most of the pace. Hormones, age, and nutrition influence it. Most “lash growth” products and tricks either support the follicles you already have or do nothing at all. Nothing on the market reliably creates new follicles.

What Makes Eyelashes Grow?

Growth happens inside the hair follicle, a small pocket in the skin of the eyelid. At the base sits the bulb, where cells divide rapidly. These cells fill with keratin and die as they are pushed outward. That hardened keratin is the lash you see.

Each follicle runs on a repeating cycle with three phases:

• Anagen is the growth phase. Lash cells divide and the lash lengthens. For eyelashes, this phase is short compared with scalp hair.
• Catagen is a transition phase. Growth stops and the follicle begins to shrink.
• Telogen is the resting phase. The old lash sits in place before it sheds and a new one starts growing.

Upper eyelashes are longer and more numerous than lower ones, and the upper lid carries roughly a couple hundred lashes per eye. Each lash grows for a few weeks to a few months before shedding. Because the growth phase is short, eyelashes stay short. That is normal anatomy, not a deficiency.

Genetics do most of the work. Your natural lash length, density, and curl are largely inherited. No product changes the genetic blueprint of a follicle. What products and habits can do is support the follicles you have so they grow as well as they are able to.

Do Lash Serums Actually Work?

It depends entirely on what is in the serum. The category is not one thing, and lumping all lash serums together is misleading.

The strongest evidence belongs to a prescription ingredient called bimatoprost. It began as a glaucoma medication, and patients noticed their lashes grew longer and darker as a side effect. That observation led to formal study, and a bimatoprost solution is FDA-approved for eyelash growth. It works by prolonging the growth phase of the lash cycle, so lashes stay in active growth longer. The effect is real but temporary. Lashes return to baseline after you stop using it.

Bimatoprost is a prescription for a reason. It can cause eye redness, itching, and darkening of the skin around the eye. It can also darken the iris, and that change may be permanent. Because of these risks, it requires a clinician’s oversight rather than an online purchase.

Over-the-counter lash serums are a different story. Many contain peptides, biotin, or plant extracts. No large human trials have confirmed that these ingredients lengthen lashes. Some may condition lashes so they look healthier and break less. That is a cosmetic effect on existing hair, not new growth. Marketing language like “clinically proven” on these products should be read carefully. The claim rarely refers to a study measuring lash length against a placebo.

One non-obvious point: many positive reviews for over-the-counter serums come from people who are also using a prescription product, wearing mascara, or applying the serum to lashes that were temporarily thin from a removable cause. When the underlying cause resolves, lashes recover on their own. The serum gets the credit.

Can Castor Oil, Coconut Oil, or Vaseline Grow Lashes?

No. There is no clinical evidence that castor oil, coconut oil, petroleum jelly, or olive oil makes eyelashes grow longer or thicker.

These oils can coat the lash and make it look slightly darker or glossier. They can reduce breakage by adding a protective layer. Neither effect is growth. The follicle does not respond to oil by producing more hair.

There is a real risk worth naming. Oils and petroleum jelly applied near the lash line can migrate into the eye and clog the oil glands along the eyelid margin. Clogged glands can lead to irritation, styes, or a chronic eyelid condition called blepharitis. Anything you put this close to the eye deserves caution.

The castor oil claim is one of the most persistent lash myths online. It likely spread because castor oil is thick, shiny, and makes lashes look fuller in photos. That is a visual effect, not a biological one.

What Lifestyle Factors Affect Eyelash Growth?

Healthy follicles need the same things healthy hair elsewhere needs: adequate protein, iron, and overall nutrition. Severe nutritional deficiency can cause hair shedding, including lashes. Correcting a genuine deficiency can restore normal growth. Taking supplements when you are not deficient does not make lashes grow faster.

Biotin deserves a specific note because it is marketed heavily for lashes and hair. In people with normal biotin levels, there is no good evidence that extra biotin improves hair growth. Some research suggests high-dose biotin can interfere with certain lab tests, including thyroid and heart marker tests, which can lead to misleading results. That is a real concern worth raising with your doctor before starting a high-dose supplement.

Other factors that influence lash health:

• Sleep and stress. Chronic stress and poor sleep are linked to hair shedding in general, though the effect on lashes specifically is less well studied.
• Rubbing and pulling. Rubbing your eyes, harsh makeup removal, and eyelash extensions that are applied or removed roughly can damage lashes and, over time, the follicle.
• Waterproof mascara. It requires more aggressive removal, which increases breakage. Gentle cleansing matters more than the mascara itself.
• Medical conditions. Thyroid disorders, iron deficiency, and skin conditions affecting the eyelid can all affect lash growth. Persistent lash thinning warrants a medical evaluation rather than another serum.

Why Do Eyelashes Thin or Fall Out?

Lash shedding is normal. Everyone loses lashes as part of the growth cycle, and a lash that falls out is usually replaced. Noticeable thinning is different and usually has a cause.

Common causes include age, genetics, thyroid problems, nutritional deficiencies, and skin conditions like blepharitis. Chemotherapy and some medications cause lash loss. So can trichotillomania, a condition where people pull out their own hair, including lashes. Eyelash extensions and harsh cosmetic habits can cause traction damage over time.

If your lashes are thinning noticeably, the useful step is to identify why before buying a product. A clinician can check thyroid function, iron status, and the eyelid itself. Treating the underlying cause is the only approach that addresses the problem rather than masking it.

Is There a Safe Way to Support Lash Growth?

The safest approach is to protect the follicles you have and address any reversible cause of thinning. That means gentle cleansing, avoiding rough handling, and giving lashes a break from extensions and heavy waterproof products.

If you want to try an over-the-counter serum, understand what you are buying. Look for products with a short ingredient list and no known irritants, and stop if you notice redness, itching, or swelling. The evidence for growth is weak, so treat any improvement as a bonus rather than an expectation.

For a prescription option, talk to a doctor or eye care professional. Bimatoprost is the only lash growth ingredient with FDA approval, and it carries real risks that need a clinician’s input. It is not a casual purchase.

One clarification that matters: no product currently available creates new eyelash follicles. Everything that works acts on existing follicles by extending growth or improving condition. That is a meaningful distinction when reading marketing claims.