Experts have warned of potential side-effects linked to some eyelash growth serums, including a permanent change in eye colour, dark circles under the eyes, and the loss of under-eye fat.
The serums are widely available in high street stores and online, and are used by millions to improve the look of eyelashes by stimulating new hair to make them longer and thicker than usual.
While the vast majority of those who use them appear to do so without adverse consequences, some women have been reporting a number of unwanted side effects, including the appearance of styes and a permanent change in eye colour.
Experts have told Yahoo News UK that users should be more aware of the potential issues they can cause and that some serums should be avoided altogether.
What are eyelash growth serums?
Eyelash growth serums are used to grow longer, fuller eyelashes and work by using a variety of ingredients to support the hairs in their growth phase. Once people stop using them, the eyelashes revert back to their natural state and grow as normal.
The products have become increasingly popular in recent years due to positive reviews from users on platforms like Instagram and TikTok (such as the one below). Market research company Polaris valued the eyelash growth serum market at $784.72 million (£671m) in 2021 and predicted it would continue to grow.
The growth serum was discovered almost by accident, according to the American Academy of Ophthalmology. Glaucoma patients using a drug called Lumigan discovered their eyelashes were getting darker and thicker because the drug contained bimatoprost, a type of hormone-like substance called a prostaglandin analog (PGA). Bimatoprost was subsequently used as a key ingredient to make a drug called Latisse, which is given to people who need to grow eyelashes.
The AOAA says that Latisse, while FDA-approved in the US, can cause unwanted side effects to the skin surrounding the eyes and to the eye colour itself. It also warned in 2019 that beauty aisles were “filled with over-the-counter serums promising to mimic Latisse's effects”. The AOAA says these serums often contain isopropyl cloprostenate, a PGA that is similar to bimatoprost but is not approved by health authorities.
In the UK, it is not thought that there are any authorised medicinal products for human use which contain isopropyl cloprostenate.
Warnings over side effects
One of the most popular eyelash growth serums in the country is UKLash, which was dubbed by the Retail Times as the “fastest-growing lash serum brand” in 2023 - the company itself claims its product is bought every 30 seconds. The serum is popular with influencers and ordinary consumers, some of whom have called it a ‘miracle’ serum and it is also available in the high-street store Sephora.
However, while it appears many people who use UKLash’s products do so without any adverse effects, some have shared side effects of using the product.
Carly Musleh, 40, from South Shields, is a cosmetic chemist who used UKLash for a few months in 2022 after receiving it as a PR sample. She posted a TikTok about her experience in December in response to a video from an influencer asking: “Anyone been using UKLash for a while and now have deep, hollow, black under eyes?”
In the video, Musleh says she developed an eye issue after using the serum.
Musleh told Yahoo News she first noticed a problem when she suffered from a swollen eye the night before her graduation: “I woke up, and my eye was very swollen and red.” She said weeks went by until the swelling eventually went down to a small solid lump with hyperpigmentation above her lash line. “It’s been 18 months, and I still have a very small lump, which thankfully is no longer noticeable,” she added.
The comments below Musleh’s video, which has been watched around 600,000 times, became a forum for discussing the product. One person commented: “UK lash is the worst! It's given me dark circles!” while another said, “I’ve started getting dark circles under my eyes, which I have NEVER had 😭 have stopped using it now.”
Another said their eye colour had changed, saying: I used UKlash, my eye colour changed slightly, I ended up with dark lines on my eyelids like eyeliner & my eyes were bloodshot red for 1 whole week.”
Another complained of similar issues, commenting: “I noticed my eyelids were darkening & itchy. Stopped using UK Lash & eyes went back to normal.”
Others said they had been using UKLash with no problems. One person said: “I use UKlash and it’s fine. No dark circles. Don’t believe the fear mongering.”
What experts have said?
The UKLash website contains clear instructions that users should avoid direct contact with their eyes, avoid using if pregnant, and stop using if redness or irritation occurs. The website also states the eyelash serum contains isopropyl cloprostenate.
UKLash has told Yahoo it adheres to "all regulations and strict EU & UK quality standards". It added: "Some statements on social media on this topic lack a scientific foundation and are unfortunately not supported by research or evaluations from the scientific community."
However, Musleh says there is still a lack of awareness of the serum’s side effects: “This video highlighted that many didn’t know about prostaglandins or that it was a drug used in eye medicines,” she said. “It’s brought awareness and understanding to a serious side effect caused by eyelash serums containing this ingredient.”
Experts have also urged users to be careful when using products containing PGAs as the side effects can vary from something minor to serious, irreversible issues.
Dr Elizabeth Hawkes, a consultant ophthalmic and oculoplastic surgeon at the Cadogan Clinic in London, told Yahoo News UK it is hard to tell just how common side effects are as there isn’t that much research into the issue. She added that some eyelash growth serums are best prescribed by a specialist doctor.
“If you experience any negative side effects, you should stop using the product and seek medical advice,” she said. “However, it is common for people to experience irritation, redness and inflammation from using serums with prostaglandin.” She said that the eyelash growth serums can cause fat cells around the eyes to shrink, leading to the sunken effect that users have been experiencing around their eyes.
She added: “If you experience any negative side effects, you should stop using the product and seek medical advice. There are many eyelash growth serums that do not contain PGAs, and I would advise using these products instead.”
Dr Leila Asfour, of the British Association of Dermatologists, said: “It is important patients are aware of the risks when using prostaglandins, that it can cause eye irritation, affect the colour of the eye (iris) permanently and therefore should be applied carefully without it going into the eye.”
*Dr Asfour said there is research still ongoing about how effective prostaglandins can be for pattern hair loss in men and women. “In clinical practice, we use it in patients who have some growth or are trying to maintain their eyelashes and eyebrows in a medical autoimmune condition called alopecia areata.” She said research has found that if there is no hair present, PGAs won’t have an effect.
UKLash told Yahoo News UK: "The safety of our customers is priority, UKLASH Original Eyelash Serum contains a very small percentage of Prostaglandin analogues (PA), which is the lowest on the market. This percentage is enough to be effective whilst minimising the risk of significant side effects.
"Prostaglandin analogues, known to support lash growth at low concentrations, are lipid compounds present in almost all human tissues. Our lash and eyebrow formulas act locally where applied, with no reported cases of long-term side effects. Any reaction typically resolves within a few days.
"On our website, we transparently list all ingredients, including the small percentage of PA. As with all new beauty products, we advise customers to test the serum before regular use. However, as with any beauty product, individual reactions can vary - that’s why we offer a money-back guarantee with proof of purchase."
"For customers with sensitivity concerns, we offer the Sensitive Serum, which contains a cocktail of active ingredients and peptides without PA, designed to strengthen, nourish, and grow lashes. We continuously innovate to develop new serums, providing a wider choice to our valued customers."
Yahoo News UK contacted the Trading Standards Agency for comment.