Lash serums are everywhere right now — but if you've spent any time reading reviews, you've probably also seen the scary words: iris colour change, hooded eyes, irritation. So it's no wonder one of the most-searched questions in beauty right now is simply: are lash serums safe?
The honest answer: most well-formulated lash serums are safe for most people — but it genuinely depends on one ingredient. Understanding that ingredient is the difference between shopping with confidence and gambling with your eyes. Here's everything you need to know, minus the scaremongering.
It all comes down to one word: prostaglandins
Many of the original, fast-acting lash serums work using prostaglandin analogues — lab-made versions of a compound first used in glaucoma eye drops (you might know the brand Latisse). They're effective, and they're FDA-approved for lash growth. So far so good.
The catch is the side effects. Health and regulatory bodies have documented that prostaglandin analogues can cause:
- Permanent iris colour change — the FDA states this darkening cannot be reversed, and it most affects people with lighter (blue, green, hazel) eyes.
- Periorbital fat loss — a sunken, hollow look around the eyes.
- Eyelid skin darkening, redness and irritation.
These aren't fringe internet rumours. The Royal Australian and New Zealand College of Ophthalmologists has issued a position statement on prostaglandins in lash serums, Canada has banned the prostaglandin analogue isopropyl cloprostenate in cosmetics, and in early 2026 the EU's Scientific Committee on Consumer Safety concluded these ingredients can't be considered safe in cosmetics at the proposed levels. France's safety agency, ANSES, also flagged cases of periorbital fat loss and iris darkening linked to a prostaglandin lash serum in late 2025.
To be fair: plenty of people use prostaglandin serums with little or no issue, and they do work. But for a daily product you're applying millimetres from your eye, a lot of people understandably decide it's not a risk worth taking — especially if they have light eyes.
What "prostaglandin-free" actually means
A prostaglandin-free lash serum simply contains none of these prostaglandin-analogue ingredients. Instead, it grows and conditions lashes using gentler, well-tolerated actives:
- Peptides like Biotinoyl Tripeptide-1 and Myristoyl Pentapeptide-17, which support the look of fuller, stronger lashes
- Biotin to strengthen and reduce breakage
- Panthenol (Pro-Vitamin B5) and Hyaluronic Acid to hydrate and condition
- Caffeine and Arginine to support the lash line
These don't carry the same documented risks of iris darkening or fat loss — which is exactly why "prostaglandin-free" has become one of the fastest-growing things shoppers look for in 2026.
How to check if YOUR lash serum is prostaglandin-free
This is the genuinely useful bit, so screenshot it. Check the ingredients list (the INCI list) and look for anything ending in:
- -prost (e.g. isopropyl cloprostenate, bimatoprost)
- -prostenol, -prostal, or -prostenolamide
If you spot any of those, it contains a prostaglandin analogue. Formulas change, so it's always worth double-checking the current ingredients before you buy — even on a brand you trust.
Our promise at By Babes
We built our Lash Growth Serum to be the serum we'd happily use ourselves, every single night — which is why it's 100% prostaglandin-free and hormone-free. It uses a peptide-powered, vegan formula, it's made in the UK, it's third-party clinically tested, and it's safe to use alongside lash extensions and contact lenses. No hormones, no nasties, no compromise — just longer, fuller, healthier-looking natural lashes.
Because feeling confident in your beauty routine should never mean worrying about what it's doing to your eyes.
The takeaway
Are lash serums safe? Yes — if you choose the right one. The single most important thing you can do is check that ingredients list for prostaglandins, especially if you have light-coloured eyes. Choose a prostaglandin-free, peptide-based formula and you get the lash results without the documented risks.
Want longer lashes without the worry? Meet our prostaglandin-free Lash Growth Serum — loved by over 100,000 babes. 💕
This article is for general information and isn't medical advice. If you have an existing eye condition or any concerns, check with your doctor, optometrist or a dermatologist before starting a new lash product.
