Prostaglandin analogues are the reason some lash serums produce dramatic growth — and the reason some users end up with darkened eyelids, irritated eyes or hollow-looking orbits. This guide explains what these ingredients are, what the documented side effects look like, how to identify them on a label in ten seconds, and what to use instead if you'd rather not take the risk.
What are prostaglandin analogues?
They're synthetic versions of prostaglandins — signalling molecules originally developed in glaucoma medication (bimatoprost), where longer, darker lashes were noticed as a side effect. Cosmetics companies adapted the chemistry into over-the-counter serums using analogues like isopropyl cloprostenate, norbimatoprost and dechloro dihydroxy difluoro ethylcloprostenolamide. They work by artificially extending the anagen (growth) phase of the lash cycle.
What side effects are documented?
- Eyelid and skin darkening (hyperpigmentation) along the application line — often reversible, sometimes slow to fade.
- Eye irritation, redness and dryness — the most common complaints.
- Prostaglandin-associated periorbitopathy (PAP) — a documented set of changes including deepening of the upper eyelid sulcus (a "sunken eye" look) and orbital fat loss with prolonged use.
- Iris colour change — rare, associated primarily with pharmaceutical bimatoprost, and permanent when it occurs.
Regulators have taken notice, repeatedly. Sweden's Medical Products Agency tested 26 lash serums back in 2013 and found prostaglandin analogues in 9 of them — three undeclared on the label — and advised consumers against using them. The US FDA warned as early as 2011 that isopropyl cloprostenate serums were effectively unapproved drugs. In February 2026, the EU's Scientific Committee on Consumer Safety adopted its final opinion that three common analogues (MDN, isopropyl cloprostenate and DDDE) cannot be considered safe in lash and brow cosmetics. In the US, Grande Cosmetics paid a US$6.25 million false-advertising settlement in 2024 over its prostaglandin serums. In Australia, bimatoprost is a Schedule 4 (prescription-only) substance. Cosmetic prostaglandin analogues are regulated as industrial chemicals by AICIS, and the TGA treats any product as therapeutic once its ingredients or its claims cross the cosmetic line. None of this means everyone who uses them will react — it means the trade-off is real and worth making knowingly.
The 10-second label check
Flip the box and scan the INCI list for anything containing "-prost" — cloprostenate, prostenolamide, norbimatoprost and relatives. If it's there, it's a prostaglandin serum regardless of what the front label says. "Naturally derived" marketing does not exclude these ingredients.
What to use instead
Conditioning serums built on peptides, biotin and panthenol take the gentler route: they condition the lashes you have, help them look and feel less brittle, and support a fuller, healthier look over 8–12 weeks — without touching the hormonal pathway. That's the entire formulation philosophy behind the Lash Originals Lash Serum: prostaglandin-free, water-based, oil-free and ophthalmologist-tested, so it suits wear alongside extensions and contact lenses. The results build more gradually — and that's the honest price of skipping the risk column above.
When to talk to a doctor
If you've experienced lid darkening or persistent irritation from any serum, stop use and see your GP or optometrist. And if you're considering prescription bimatoprost for maximum effect, that's exactly the conversation to have with a professional first. This article is general information, not medical advice.
Browse: our prostaglandin-free lash range.
Related reading
- Brow serums: what the evidence supports
- Prostaglandin-free brow serums, compared
- Do Lash Serums Actually Work? What the Science Says (2026)
- Latisse vs Over-the-Counter Lash Serums in Australia
- Best Eyelash Serum in Australia (2026)
- Prostaglandin-Free Lash Serums Explained: What the Ingredient List Actually Tells You
Sources
- Therapeutic Goods Administration (TGA) — Determining if your product is a cosmetic or therapeutic good
- Therapeutic Goods Administration (TGA) — Latisse (bimatoprost) ARTG cancellation record
Written by the Lash Originals Editorial Team · Reviewed 7 September 2026. This article is general cosmetic information, not medical advice.