Lash serum questions, answered plainly

Four to six weeks for a peptide serum, around three for a prostaglandin formula. The serum acts on lashes that are in their growth phase, so a lash has to grow out before you can see the difference — nothing can lengthen a lash that is already on your face. Judge at week eight.

On our panel, between 1.1 mm and 2.7 mm at week twelve depending on the serum, with individual results varying by about a millimetre either side of the average. Anyone promising you 5 mm is selling, not measuring.

No. Within eight to ten weeks — one full lash cycle — you are back to your natural length. This is why we score cost per month rather than cost per tube.

Consistency and starting point. Missed nights were the clearest predictor of a poor result on our panel, and someone whose lashes have been thinned by extensions or heavy mascara has more room to improve than someone starting with a healthy lash line.

They are effective and they carry real risks: permanent iris darkening in blue, green and hazel eyes, darkening of the lid skin, hollowing of the upper lid, and redness or dryness. They are legal as cosmetics in the UK. We cap their safety score and label every one in the ranking.

Ask your midwife or GP. Prostaglandin analogues should be avoided. Peptide and conditioning formulas are generally treated as lower risk, but this is a medical decision rather than a cosmetic one, and we will not make it for you.

Mild tingling in the first week is common and usually settles. Stinging that continues, or any redness, swelling or change in vision, means stop and get advice. Fragrance and alcohol high in the ingredient list are the usual culprits in an otherwise gentle product.

Not without speaking to your ophthalmologist. Prostaglandin analogues are chemically related to glaucoma medication and can interfere with treatment and with pressure readings. Tell your eye doctor if you use any lash serum.

Yes to both, and it is one of the better reasons to use a serum, since extensions and lifts stress the natural lash. Apply to the lash line rather than through the extensions, and check with your technician — oil-rich formulas can loosen adhesive.

Yes. Apply at night with lenses out and give it a few minutes to dry before you sleep.

Peptide formulas, yes — several are sold for both. Keep prostaglandin formulas to the lash line, because anything that migrates onto surrounding skin can darken it.

Night, on a clean dry lid. Applied in the morning it sits under makeup, migrates, and ends up doing more for your lower lid than your lashes.

We do. This site carries no affiliate links, no advertising and no sponsored content, so the ranking has nothing to sell you — the link beside each serum points at the brand’s own site and earns us nothing. Every product was bought at full retail price. The method page has the rest.

Whenever a reformulation, a new serum worth testing, or a lasting price change makes the current list wrong. The date at the top of the ranking is the date it was last reviewed.