Why Do Prostaglandin Analogs Have a Bad Reputation and is it Deserved?

Prostaglandin analogues sit in a curious place in beauty. They are drug-like molecules that extend the hair follicle’s growth phase and were first noticed by ophthalmologists, not make-up artists. Patients using daily glaucoma drops developed longer, thicker, darker lashes. That observation led to the first licensed lash medicine, bimatoprost 0.03 per cent, which remains the only FDA-approved active with strong controlled data showing meaningful gains in lash length, thickness and darkness within 16 weeks, with mostly mild and transient irritation reported in trials. The appeal for aesthetics is obvious. The controversy is too.

The bad reputation grew out of a specific chapter in the market’s history. A wave of over-the-counter lash and brow serums deployed prostaglandin analogues such as isopropyl cloprostenate while presenting themselves as cosmetics. In the United States, the FDA warned that these were unapproved drugs, not cosmetics, because they were designed to affect body structure and carried drug-type risks without the labelling, dosing and oversight that medicines require. In Europe, the Scientific Committee on Consumer Safety reviewed several analogues used near the eye and concluded that the safety evidence was insufficient at the concentrations proposed. Adverse event reports and headline legal cases followed, cementing the perception that lash serums are risky. That history still colours how professionals and consumers view the entire category.

The scientific picture is more nuanced. Among actives assessed since 2024, bimatoprost sits at the top for efficacy. Other analogues such as latanoprost, tafluprost and fluprostenol show potential but are backed by thinner data in cosmetic settings. Peptide and vitamin blends marketed as prostaglandin-free are generally safer but deliver subtler and less predictable results. The pattern is consistent: the strongest lash changes come from prostaglandin pharmacology, but the margin of safety depends on which molecule is used, at what dose, in what vehicle, and how precisely it is applied.

Safety concerns are real and should be explained plainly. The common effects are ocular redness and local irritation around the lash line. Less frequent but weightier effects include eyelid skin darkening, iris colour change in mixed or light irides, and a recognised cluster called prostaglandin-associated periorbitopathy that has included periorbital fat loss and eyelid changes in long-term daily eye-drop users. Risk seems to relate to the specific analogue, the concentration and preservative system, the route of delivery and cumulative exposure over time. That is why the route of administration matters so much. Daily drops placed directly into the eye expose internal tissues and deliver higher effective doses than a tiny bead of serum painted along the upper lash margin and blotted.

Brand developers argue that good formulation and careful delivery can hold risk down while preserving results. “Some Prostaglandin Analogs (also known as PGAs), like those RevitaLash Cosmetics uses, are used only as ingredients in cosmetics” comments RevitaLash Cosmetics Founder & CEO, Dr Dr Micheal Brikenhoff. “The confusion regarding safety has perhaps occurred because there are other PGAs that are ingredients in eye drop medications used to treat a medical condition, glaucoma, by lowering interocular eye pressure. Not only are these watery eye drop medications inserted directly into the eye, but they also contain a higher concentration of the PGA. These eye drop medications have an excellent safety profile, but some local side effects have been reported with their use, such as darkening of iris color.” The distinction they draw is both pharmacological and practical. In medicine, bimatoprost was dosed, studied and licensed as a drug with single-use applicators, specific instructions and monitoring. By contrast, early cosmetic serums often disclosed little about dose, used mascara-style wands and were sold without medical guidance. That gap helps explain why similar chemistry produced different reputations.

“In contrast, RevitaLash Advanced lash serums are applied onto the eyelashes with a fine brush applicator designed to apply a very small amount of serum - and verified through our safety testing. Additionally, our formulas include thickeners to keep the serum on the lashes. Each of these factors helps to ensure that the serum remains on the lashes that we are wanting to beautify and not getting onto the skin or into the eye. We also invested in a variety of clinical testing, and our products have been reviewed by experts like dermatologists and ophthalmologists to ensure they are safe and non-irritating for our users.

We have the only ophthalmologist-developed lash and brow serums available, and we will continue our commitment to ensuring our products are safe and thoughtfully made.”

So is the reputation deserved. Partly. It was earned by products that used potent analogues while sidestepping drug-level testing, clear warnings and medical supervision. Those products attracted regulators and lawyers for good reasons. At the same time, drug-status bimatoprost shows that with the right molecule at the right dose, applied sparingly to the upper lash line with a precise applicator and monitored sensibly, most adverse events are mild and manageable and the efficacy is best in class. A binary view of safe versus dangerous does not help practitioners or patients. The more useful lens is to identify the active, check its regulatory status in your market, scrutinise the concentration and the applicator, and match the product to the person in front of you. Avoid prostaglandins in pregnancy and in those with uveitis or retinal disease unless under ophthalmic care. Be explicit with fair-skinned or hazel-eyed users about pigmentation risk. Emphasise that more is not better and that excess should be blotted.

Nonetheless, prostaglandin analogues deliver the most reliable lash growth in aesthetics, which is why the category endures. Their pharmacology also places them under drug-grade scrutiny, which is why casual cosmetic use has been reined in. If professionals treat these actives as medicines in all but name, insist on clarity about what is in the bottle and how it is used, and keep a close eye on early signs of trouble, then the benefits can be realised without repeating the mistakes that gave PGAs a bad name.