Eyelash serums are popular, and it's not hard to see why. The idea of growing your own long, feathery lashes rather than relying on falsies or the magic of mascara can be enticing. And while that promise alone might have you buying up multiple eyelash serums without a second thought, you might want to take a strange side effect into account first. Some eyelash serum formulas can apparently change the color of your eyes or, at the very least, darken the skin around your eyes.
Muneeb Shah, D.O., a dermatology resident physician, pointed out as much in a recent Instagram post. "It turns out that lash boosting serums can actually be quite effective," says Dr. Shah, in the video. "Especially the ones that contain prostaglandins or prostaglandin analogues." But that's when he dropped the mind-blowing side effect. "Unfortunately, they can also cause hyperpigmentation around the eye. But not just that — they may actually darken your eye color." (Related: The Best Eyelash Growth Serums for Serious Length, According to Customer Reviews)
Prostaglandins are lipids that have various hormone-like effects on the body. One of those is that they can boost last growth when included in a topical eyelash serum formula. Prostaglandin analogues, which are what are included in lash serum formulas, are compounds that are similar to prostaglandins and can bind to the same hormone receptors in your body and are likewise linked to eyelash growth.
Latisse, the only prescription eyelash serum, contains bimatoprost, a prostaglandin analogue, with research-backed lash-growing potential. Darkening of the eyelid, eye irritation, dryness, redness, and increased brown pigmentation of the iris (the colored part of the eye) are all listed as side effects of Latisse on its website. The darkening of the eyelid tends to go back to normal if the Latisse user stops using the product, according to the company. However, changing of the iris color is rare, but it's likely to be permanent when it does happen, according to the company. (Related: 15,000 People On Amazon Are Obsessed with This Dual Lash and Brow Serum)
Given that Latisse requires an Rx, if you do use the product, your doctor likely would have (ahem, should have) brought these side effects up before prescribing the med. But OTC eyelash serums can also potentially change your eye color, as Dr. Shah pointed out in his post. He listed a few examples: Grande Lash (Buy It, $65, sephora.com), Neu Lash (Buy It, nordstrom.com), Rodan + Fields Lash Boost (Buy It, $155, rodanandfields.com), and Babe Lash Essential Serum (Buy It, $65, babelash.com), all of which contain the prostaglandin analogue isopropyl cloprostenate. Eye doctors have criticized cosmetic brands for selling products containing prostaglandin analogues without adequately warning customers about potential side effects, reports to BuzzFeed. (Related: What I Learned from Trying Latisse to Boost Eyelash Growth)
Rare as it may be, a permanent change in eye color isn't something to take likely, so it's definitely worth taking into consideration when deciding whether to try a lash serum.