"They said this eyelash serum guarantees results, so I splurged on it."
This is a story about the expensive eyelash serums that have been appearing more and more frequently on SNS and social media lately. Along with reviews saying that eyelashes become darker and grow faster, phrases such as "guaranteed results" and "results assured" tend to follow.
Today, we will take a careful look at whether these products really work, and more importantly, whether there are any safety concerns, together with a review of the full ingredient list.
Key Summary
✔ Some expensive eyelash serums contain isopropyl cloprostenate, a prostaglandin analogue.
✔ Ingredients in this class may act to make eyelashes longer and darker, but adverse reactions such as eyelid irritation, pigment changes, and hollowing around the eyes have also been reported.
✔ The mere fact that a product is sold as a cosmetic does not mean that its safety for long-term use around the eyes has been sufficiently confirmed.
✔ Check the ingredient list, and discontinue use immediately if any abnormal symptoms appear.
Why Are They So Expensive — Even the Distribution Channels Differ
Ordinary eyelash serums usually cost around 20,000–30,000 won. However, certain products that have recently drawn attention are considerably expensive, at over 100,000 won per bottle. The sales channels are also somewhat different. Rather than being sold openly online, they are often distributed through offline affiliate outlets such as aesthetic salons, accompanied by strong messages such as "guaranteed results" and "results assured."
The higher the price and the stronger the advertising, the more carefully consumers need to check the ingredients and the evidence behind them.
The Key Ingredient to Look for in the Full Ingredient List
When I actually tried to check the full ingredient list of one representative product, the ingredients were not listed on the product's website. Fortunately, those who import and distribute products from overseas are obliged to disclose the full ingredient list, so I was able to confirm it through import-related documents.
The ingredient list was quite long, and the key one was the ingredient listed at the very end. That is isopropyl cloprostenate.
Full cosmetic ingredient lists are generally arranged starting from the ingredients with the highest content, but the order can differ for ingredients blended in small amounts. Therefore, the exact content cannot be determined simply because an ingredient appears at the end of the list. However, isopropyl cloprostenate may exert pharmacological action even at very low concentrations, so its very presence in the ingredient list warrants careful attention.
Prostaglandin Derivatives — A Long-Known Story
Isopropyl cloprostenate belongs to the class of prostaglandin derivatives. The fact that applying prostaglandin derivatives around the eyes makes eyelashes and eyebrows darker and thicker is not actually a new discovery.
This is because people using glaucoma eye drops have long commonly reported that "their eyelashes became darker." Taking note of this, the multinational pharmaceutical company Allergan created Latisse, which used bimatoprost, a prostaglandin derivative, at a lower dose than for glaucoma treatment, for the purpose of eyelash lengthening. Latisse is a prescription drug approved by the US FDA, and it was previously available in Korea as well.
Side Effects of Latisse and Prostaglandin-Class Ingredients
Latisse, which contains bimatoprost, is a prescription drug approved by the US FDA for the treatment of eyelash hypotrichosis. As a medication with confirmed effects, adverse reactions requiring caution—such as itching and redness of the eyelid skin and pigment changes—are also known. It is currently difficult to obtain in Korea in general, but it is difficult to attribute the specific reason for the discontinuation of its domestic distribution to side effects alone.
Why It Is Distributed as a Cosmetic Rather Than a Drug
Although the ingredients belong to the same class, one was a prescription drug while the other is sold as a cosmetic. The difference lies in the laws that apply to each.
- Drugs require supervision and approval from the Ministry of Food and Drug Safety for every ingredient they contain.
- Cosmetics follow what is known as negative regulation. Under this approach, an ingredient may be used as long as it is not on the prohibited list saying "do not include these ingredients."
Isopropyl cloprostenate is included in very small amounts and is not currently designated as a prohibited ingredient under cosmetic raw material management standards, so it is used in some products. However, being sold as a cosmetic does not mean that its safety for long-term use around the eyes has been sufficiently confirmed.
What Side Effects Should You Watch Out For?
The most common issue is irritation at the application site. Stinging, itching, redness, or swelling may occur. For eyelashes to grow, the product must be applied consistently for about 6 weeks rather than just a day or two, and if irritation is repeated during that period, inflammation may persist like contact dermatitis. Persistent inflammation can lead to hyperpigmentation, which may make people feel that "their dark circles have gotten darker." That said, pigmentation resulting from inflammation often gradually returns to normal once use is discontinued.
A more important concern is the atrophy of fat around the eyes with long-term use. With age, the fat in the eyelids decreases and the lines deepen; with long-term use, a reduction in periorbital fat and a deepening appearance of the eyelid sulcus have been reported in some cases. There are reports that these changes do not fully revert even after discontinuing use. This is known to be a characteristic shared by prostaglandin derivative-class agents such as bimatoprost.
This does not mean that the effects are "false." However, since these products are used for cosmetic purposes, I would like to point out that you need to weigh the benefits you gain against the side effects you may have to accept. If you decide to use one, be sure to follow the usage instructions and precautions indicated on the product, and take care that it does not run into the eye or onto the lower eyelid. If any abnormal symptoms appear, it is advisable to stop use immediately and seek medical care.
Frequently Asked Questions
If it is sold as a cosmetic, doesn't that mean its safety has been confirmed?
The fact that a product can be sold as a cosmetic is not the same as its safety for long-term use around the eyes having been sufficiently proven. In particular, prostaglandin analogues may exert pharmacological action even at low concentrations, so you should check the ingredients and the area of application. If redness of the eye, eyelid irritation, pigment changes, or hollowing around the eyes occurs, it is advisable to stop use and consult an ophthalmologist or dermatologist.
I developed pigmentation—will it return to normal if I stop using it?
Skin pigmentation accompanying irritation or inflammation may gradually fade after discontinuing use, but the degree and duration of recovery vary from person to person.
With prostaglandin-class ingredients, a reduction in periorbital fat and a deepening appearance of the eyelid sulcus have been reported. The frequency of occurrence and the possibility of recovery vary depending on the ingredient, concentration, duration of use, and individual condition, making them difficult to predict precisely.
I still want darker eyelashes—is there any way?
If you already have eyebrows and eyelashes, we recommend deciding carefully, taking both irritation and cost into account. If your concern is a lack of eyebrow density itself, you can compare other options such as an eyebrow transplant through a consultation. Whatever the method, suitability differs depending on individual condition, so please discuss it thoroughly with a specialist.
Can I use it while pregnant or preparing for pregnancy?
If you are pregnant, breastfeeding, or preparing for pregnancy, it is advisable not to use products containing prostaglandin analogues on your own. Please check the product's ingredients and consult with an obstetrician-gynecologist or ophthalmologist.
What symptoms should prompt me to stop using it?
If persistent redness, pain, severe itching or swelling, changes in vision, changes in the skin color around the eyes, or a sudden hollowed appearance of the eyelids occurs, it is advisable to stop use and consult an ophthalmologist.
If I use an eyelash serum, will my lashes return to their original state once I stop?
Eyelashes lengthened by prostaglandin analogues may gradually return to their original state according to the eyelash growth cycle once use is discontinued. However, there are individual differences, and whether side effects resolve may vary depending on the symptom.
In Summary
- The "effect" of expensive eyelash serums generally comes from prostaglandin derivatives (isopropyl cloprostenate).
- Latisse, a prescription drug using an ingredient of the same class, is a US FDA-approved product and is currently difficult to obtain in Korea in general.
- Current products appear to be distributed in a blind spot of the negative regulation system for cosmetics.
- This does not mean they have no effect at all, but you should be aware of the possibility of irritation, pigmentation, and periorbital fat atrophy and make a careful judgment.
It is easy to be swayed by the phrase "guaranteed results," but checking both the ingredients and the side effects is ultimately the way to protect yourself.
References
- Prostaglandin-associated periorbitopathy. Indian Journal of Ophthalmology. 2016. View original
- Periorbital changes associated with topical bimatoprost. Ophthalmic Plastic and Reconstructive Surgery. 2008. View original
- Periorbital fat atrophy — an unfamiliar side effect of prostaglandin analogues. Orbit. 2010. View original
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This article was adapted from a YouTube video by Director Yoo Hwa-jeong of Modi Hair Plant Clinic. It is intended to provide general medical information and does not replace individual diagnosis or treatment.
This article was uploaded after review by medical staff.