Feeling Nerdy? Here's a little more in depth

Lash serums promise longer, fuller-looking lashes, and some deliver. Not every lash serum works the same way , and "available without a prescription" does not mean "risk free". 

Lash serums generally fall into two groups:

1. Prostaglandin: can actively influence the lash-growth cycle

2. Non-prostaglandin: use ingredients such as peptides, growth factors, conditioning ingredients or botanical extracts to support the health and appearance of lashes.

Before you continue to read, consider the type of change you are looking for:

• Dramatic: length and density

• Condition: less breakage more shine

• Hope: in a bottle

First, How Do Eyelashes Grow?

Every eyelash naturally moves through three stages:

• Anagen: the active growth stage

• Catagen: a short transition stage

• Telogen: the resting and shedding stage

Unlike scalp hair, lashes spend only a short time actively growing. Individual lashes are also cycling independently, which is why they do not all grow, rest, or shed at once.

A lash serum may attempt to extend the growth phase, encourage follicles to enter the growth phase, improve the condition of the lash fiber, or reduce breakage. The result—and the potential risk—depends heavily on the active ingredients.

Prostaglandin Based Lash Serums

Prostaglandin analogs are the ingredients most strongly associated with noticeable changes in lash length, darkness, and thickness. They affect the lash-growth cycle rather than simply conditioning the hair. There is one FDA approved ingredient Bimatoprost, which is available by prescription and several non-FDA approved ingredients of which I will address Isopropyl Cloprostenante because it is available in the most commonly used OTC serums.

Bimatoprost

Benefits:

• Originally used as an eye medication. Increased lash growth was noticed as a side effect

• Strongest clinical evidence for increasing lash length, thickness and darkness

• Prescribed and used under medical supervision

Drawbacks:

• Requires prescription

• Can cause redness, itching, dryness, irritation or darkening of eyelid skin

• Can cause changes around the eye such as loss of orbital fat making eyes look more hollow

• Can darken the color of the iris, which may be permanent

Isopropyl Coprostenante

Benefits:

• Often produces noticeable lash growth

• Has been reported to produce darker-looking lashes

• Available in nonprescription formulas such as Grande Lash, Babe Original Essential Eyelash Serum, Rodan + Fields Lash Boost, Rapid Lash, and Borboleta. 

Drawbacks:

• Not FDA-approved for eyelash growth

• Long-term safety information is limited

• Can cause redness, itching, dryness, irritation or darkening of eyelid skin

• Can cause changes around the eye such as loss of orbital fat making eyes look more hollow

• Can darken the color of the iris, which may be permanent

• Be careful of product placement if you use this product. Unwanted hair growth may occur wherever stray product lands

A Note About Over-the-Counter (OTC) Serums

• Cosmetic lash serums do not generally undergo FDA premarket approval to prove that they are effective or safe before being sold (it does not mean they are unsafe, but I would not purchase a product that does not have a strong presence on the market or a well funded Research and Development department).

• Research has found exampes of online lash serums containing undeclared prostaglandin-related substances or ingredients that did not match the label. (Beware of a product that works too good, they are probably sneaking in unapproved ingredients)

• Brand reputation, ingredient transparency, careful application and realistic expectations are important!

Non-Prostaglandin Lash Serums

Non-Prostaglandin Lash Serums are often a better fit for clients who want to condition fragile lashes and want to avoid the side-effects of prostaglandin-related ingredients.

Peptides

Peptides are small chains of amino acids often included in lash and brow serums. Common examples include myristoyl hexapeptide-16 and acetyl tetrapeptide-3.

Researchers have proposed that certain peptides may:

• Support keratin production

• Condition and strengthen the lash fiber

• Support activity around the hair follicle

• Help reduce the appearance of breakage

• Encourage healthier-looking, fuller lashes over time

Peptides are not magic fertilizer for lashes, but they make sense in a well-formulated conditioning serum. They are especially helpful when the goal is stronger, healthier-looking lashes rather than the dramatic growth associated with prostaglandin ingredients.

Growth Factors

Growth factors are signaling molecules involved in cell growth, repair, and communication. In hair-related products, they are intended to support the environment surrounding the follicle and influence parts of the growth cycle.

One small study of a serum containing several growth factors reported improvements in lash curl, thickness, luster, length, and volume over 90 days, with no adverse effects observed during the study. However, the study was small and did not use the strongest type of controlled research design.

There is also a formulation challenge: growth factors are relatively large molecules, and their ability to penetrate intact skin is limited. This is another case where you want to look for a company that has a well funded research and development department, which makes the price of a viable product more than many customers are looking for. My preliminary search has found products ranging from $75-$110/tube.

My take: Growth factors show promise in a carefully formulated product and I look forward to seeing some great developments in this field. I consider them promising—not proven miracle workers.

Panthenol

Panthenol is a form of provitamin B5 frequently used to moisturize and condition hair.

In a lash serum, it may:

• Improve flexibility

• Reduce dryness

• Help lashes feel softer

• Make brittle lashes less likely to break

• Improve shine and overall appearance

There is not strong evidence that panthenol causes eyelashes to grow longer but plays a role in helping existing lashes remain conditioned and look healthier.

Proline

Proline is an amino acid involved in collagen formation and hair structure. It is sometimes added to lash formulas to support the strength and condition of the hair fiber.

Although it is considered suitable for use in cosmetic products, there is currently little direct evidence showing that topical proline increases eyelash growth. It may not be a star of the show, but can be a good supporting player.

Ginseng

Ginseng is included in some botanical lash and brow formulas because laboratory research suggests it may influence stages of the hair-growth cycle.

However, much of the research is preclinical or related to scalp hair. We still do not have enough good human research involving eyelashes to know how effective it is when applied along the lash line.

Pumpkin Seed Oil

Pumpkin seed oil has antioxidant and anti-inflammatory properties and has shown encouraging results in some studies involving scalp hair.

That does not automatically mean it grows eyelashes. The eyelid is a delicate area, and there are currently no strong studies confirming its safety or effectiveness specifically for lash growth. That being said, if you are looking to use an oil on your lashes, anyway, you may want to consider a high quality, cold-pressed pumpkin seed oil.

Jarilla-Coffea Extract for Brows and Lashes

Jarilla-Coffea combines extracts associated with Larrea divaricata and Coffea arabica. The combination has traditionally been used in Argentina for thinning brows and lashes.

In one very small, three-month study involving nine women, the formula was associated with an increase in eyelash thickness, and no adverse eye irritation was reported. Because the study was so small, the findings should be viewed as encouraging rather than conclusive.

I find Jarilla-Coffea especially interesting for brow serums, where the product is applied farther from the eye itself. It may be worth considering as part of a well-formulated brow-conditioning product, but it needs more research before strong growth claims can be made. That being said, I have not done research to find a product with this ingredient. If you find one, let me kno.

What About Castor Oil?

Castor oil may coat, soften, and condition the hair. This can help lashes or brows look glossier and may reduce breakage caused by dryness.

What it has not convincingly demonstrated is the ability to create significant new lash growth.

Most claims that castor oil dramatically grows lashes are anecdotal. That does not make it useless—it simply means its likely benefits are more about conditioning what you already have than awakening a parade of brand-new lashes.

It can also migrate into the eyes and cause irritation, so more is definitely not better.

How to Read a Lash-Serum Label

A product may contain a prostaglandin analog even when the front label describes it as a cosmetic conditioning serum.

Names worth recognizing include:

• Bimatoprost

• Isopropyl cloprostenate

• Dechloro ethylcloprostenolamide

• Fluprostenol-related ingredients

• Ingredients ending in -prost, -prostenate, or -prostenolamide

An ingredient name alone does not tell you everything about a finished formula, but it can help you recognize when a serum may act more like a prostaglandin product than a simple conditioner.

Lash-Serum Safety Tips

• Apply only the recommended amount.

• Use a thin line along the upper lash line unless the product specifically directs otherwise.

• Do not apply a lash serum inside the eye or along the waterline.

• Avoid using the same applicator on both eyes if contamination is possible.

• Stop use if you develop persistent redness, swelling, itching, pain, discharge, vision changes, darkening of the iris, or noticeable hollowing around the eyes.

• Speak with an eye-care professional before use if you have an eye condition, use glaucoma medication, have had eye surgery, are pregnant or nursing, or frequently experience eye irritation.

• Remember that more product does not equal faster growth. It usually just means more opportunity for the serum to travel somewhere it does not belong.

So, Which Type Is Right for You?

Choose based on your goal—not simply the most dramatic before-and-after photo.

You may prefer a non-prostaglandin serum when:

• Your lashes are dry, brittle, or frequently breaking

• You primarily want conditioning and improved appearance

• You are concerned about prostaglandin-related side effects

• You are comfortable with gradual or subtle results

Look for thoughtfully formulated products containing ingredients such as peptides, panthenol, conditioning agents, and possibly growth factors.

Speak with a medical provider about prescription bimatoprost when:

• You are seeking a stronger, evidence-supported change in lash growth

• Your lashes are noticeably sparse

• You understand that monitoring and careful application are important

• You are prepared to discuss your eye health and the potential side effects

My Esthetician’s Perspective

I love a good beauty product—but I also believe you deserve to know what is creating the result.

A serum that conditions and protects your lashes is different from a product that biologically alters the growth cycle. Neither category is automatically right or wrong. The important thing is choosing intentionally, using the product correctly, and knowing which changes deserve professional attention.

Healthy lashes may not always arrive with fireworks. Sometimes the win is simply less breakage, better flexibility, and lashes that look fuller because they are being treated kindly.

This information is provided for general education and is not a diagnosis or medical recommendation. An esthetician can help you review cosmetic ingredients and support the health and appearance of your lashes and brows, but eye conditions, unexpected hair loss, medication questions, or reactions around the eyes should be evaluated by an appropriate licensed medical or eye-care provider.

*Source: “Eyelash Serums: A Comprehensive Review,” published in the Journal of Cosmetic Dermatology in 2024. *