Most lash serums use an ingredient that's actually a glaucoma drug. And the side effects can change how your eyes look — for good.
The before-and-afters are real. So are the side effects most brands won't talk about.
Every TikTok feed is full of lash serums right now. The before-and-afters look amazing. The reviews are glowing. The lashes? Real and really long.
But so are the side effects most brands don't want to talk about.
Most of the top-selling lash serums use something called prostaglandins. Here's the wild part: they're actually a drug made to treat glaucoma (an eye disease). Yes — a drug for treating eye problems, in your lash serum. They do make your lashes grow. But they also cause side effects that can change how your eyes look forever — even after you stop using them.
We looked at what the doctors say. We spoke to women who've been there. We sent seven top-selling serums to a real lab for testing. What we found is worth knowing before you buy your next one.
If your lashes look great but your eyes are always red, itchy, or stinging — that's not random.
Prostaglandins cause inflammation. That's how they make hairs grow longer (they keep the growth phase going). But that same inflammation can hurt your eyes. Women using these serums often get redness that won't go away, a gritty feeling like there's something in their eye, pain when they look at lights, and itchy lash lines that get worse the more they use it.
It usually starts small. A bit of redness in the morning. A burn after you put it on. But since you can see your lashes growing, you keep going. You think it'll settle down. It usually doesn't. For a lot of women, the irritation gets worse — and some develop pink eye (conjunctivitis) that sticks around even after they stop.
If you use a lash serum and you're reaching for eye drops more than you used to? That's not your eyes "adjusting." That's them telling you something's wrong.
Sounds dramatic, right? It's also real — and documented in medical journals for over 20 years.
Prostaglandins can slowly darken the coloured part of your eye (called iris hyperpigmentation). Doctors first saw this in glaucoma patients using these drugs as eye drops. Now they're seeing it in women using lash serums too. And once your eye colour changes? It usually doesn't go back.
Who's most at risk? Women with lighter eyes — blue, green, or hazel. If your eyes have flecks of different colours, the lighter shade gets darker first. It happens slowly, over months. By the time you notice it in a photo, it's too late. The change is locked in.
Think about this for a sec. A beauty product you bought to look prettier can change your eye colour — forever. And no one is telling you. Why? Because lash serums are sold as makeup, not medicine. So the brands don't have to list the warnings.
Go on Reddit or any skincare forum. You'll find thousands of women with the same story. They started using a lash serum. Their lashes grew. Then they noticed their eye skin getting darker. Some blamed stress. Some blamed bad sleep. Most didn't figure out it was the serum for six months or more.
This is called periorbital hyperpigmentation — the fancy term for the skin around your eyes getting darker. Prostaglandin lash serums are one of the biggest causes. It takes 3 to 6 months to show up. First it's just a bit darker at your lash line. Then it spreads across your eyelid. Sometimes it even goes under your eyes.
Here's the tough part: it doesn't always fade. Some women see it get lighter after a year of not using the serum. Others say it never fully goes away. You can try skin treatments — vitamin C, peels, special creams — but nothing is guaranteed to fix it.
That's a lot to pay for longer lashes. Especially when there's another way.
This is the side effect doctors worry about most. And it's been all over the news the past two years as more women speak up.
Your eyes have tiny fat pads around them. Those are what give you that soft, young, full look. Prostaglandins can slowly shrink them — doctors call this orbital fat loss. When those fat pads shrink, your eyes look sunken. Hollow. Older. Some doctors now call it "prostaglandin face" — they see it so often they gave it a name.
Here's why it happens. Prostaglandins don't just work on your hair. They also affect the fat under your skin. Over time, that fat gets thinner. And unlike weight changes on the rest of your body — this fat doesn't come back. The only fix? Filler injections. And you need to keep getting them. Forever.
Who's most at risk? Women who use these serums for a year or more. Which is exactly how long most lash products tell you to use them to "keep your results." In other words — the product is designed to be used long enough to do the damage.
This is the side effect that made us start By Babes.
Our founder started By Babes after watching friends deal with all of this. She wanted to prove you could have long, full lashes — without the scary ingredients.
So we built our own serum. It uses peptides, biotin, and vitamins. No prostaglandins. No hormones. Nothing that could hurt your eyes. Then we did something no other lash brand does: we sent our serum to a real lab. They tested it against seven of the UK's top lash serums. All side by side.
The lab tested how well each serum grows lash-line skin cells. Same dose. Same conditions. 72 hours. Here's what happened.
At the lowest dose tested, our serum beat every other serum on the market. Including the big expensive brands. Including the ones going viral on TikTok. We didn't just match them — we beat them. Without any of the side effects.
Since then? Over 180,000 bottles sold across the UK. Over 2,400 verified reviews. No prostaglandins. No eye colour changes. No hollow eyes. Just real lash growth you can see in 2–12 weeks — safely.
Made in the UK. Vegan. Cruelty-free. And we're the only brand in our space that's put our serum in a real lab — and shared the results. If you're done choosing between pretty lashes and safe ones? You don't have to anymore.
Made for women who want long lashes — without the damage. Order today and get 4 FREE face masks to help your skin recover while your lashes grow back.
