Prostaglandins vs. peptides: what’s really in your lash serum
Almost every lash serum on the US market relies on one of two ingredient families. One is more potent. The other is gentler on your eyes. Here is how to tell them apart and which one fits you.
- Prostaglandin analogs have the strongest evidence for lash growth, and the most side effects.
- Peptide serums are gentler; their evidence comes mostly from brand-run studies.
- Choose a prostaglandin-free formula if you have sensitive or dry eyes or wear contacts.
- Both need consistent use. Results fade gradually after you stop.
What are prostaglandin analogs?
Prostaglandin analogs are lab-made compounds similar to fatty substances your body produces naturally. In lash serums they extend the anagen, or growth, phase of each lash, so lashes grow longer before they shed. The effect was first noticed in patients using prostaglandin eye drops for glaucoma, and one of these drugs, bimatoprost, was later approved in the US to treat thin or short lashes.
On a cosmetic ingredient list, look for names such as isopropyl cloprostenate, dechloro dihydroxy difluoro ethylcloprostenolamide or methylamido dihydro noralfaprostal.
In our ranking, QUALASH, GrandeLASH-MD, UKLASH, Babe and RapidLash contain a prostaglandin analog.
What are peptide serums?
Peptides are short chains of amino acids. In lash serums, peptides such as myristoyl pentapeptide-17 are thought to support keratin production, the protein lashes are made of. They usually come with conditioning ingredients like biotin and panthenol. Lashes look fuller and break less, with a smaller expected effect on length.
In our ranking, OLAPLEX LASHBOND, VEGAMOUR GRO, LASHFOOD and The Ordinary are prostaglandin-free.
Prostaglandins vs. peptides compared
| Prostaglandin analog | Peptide / prostaglandin-free | |
|---|---|---|
| How it works | Extends the lash growth phase | Conditions and supports lash structure |
| Strength of evidence | Strongest (incl. an FDA-approved drug) | Mostly brand-run studies |
| Typical brand timeline | Often 4–6 weeks to first change | Often 6–12 weeks |
| Irritation risk | Higher | Generally lower |
| Contact lenses | Remove first; ask your doctor | Remove first; follow the label |
| Best for | Maximum length, tolerant eyes | Sensitive eyes, conditioning |
Side effects
With prostaglandin serums, the most common side effects are redness and itching at the lash line. Less common effects include darkening of the eyelid skin and, reported mainly with prescription eye drops, darkening of the iris. Peptide serums rarely cause more than mild irritation, usually from fragrance or preservatives.
Which should you choose?
Choose a prostaglandin serum if length is your priority and your eyes tolerate products well. Our featured pick is QUALASH Advanced Eyelash Growth Serum. Choose a prostaglandin-free serum if you have sensitive or dry eyes, wear contacts, or want a gentler routine; our pick in that category is OLAPLEX LASHBOND Building Serum. See the full 2026 ranking.
How to apply a lash serum
- Remove makeup and wash your face.
- Make sure the lash line is fully dry.
- Wipe excess product off the brush.
- Draw one thin line along the upper lash line, like eyeliner.
- Let it dry for 2 minutes before applying other products.
See the 10 lash serums in our 2026 ranking, from prostaglandin-free to budget picks.
Best lash serums 2026 ›- LATISSE (bimatoprost ophthalmic solution) 0.03% — US prescribing information.
- US FDA information on cosmetics and eyelash growth products.
- Peer-reviewed studies on prostaglandin analogs and eyelash hypertrichosis.
- Brand-published ingredient lists and study summaries for the serums in our ranking.
This article is for information only and is not medical advice. Some links may be affiliate links; how we make money.
