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Ranked #15 of 15 Contains a prostaglandin analogue

Long4Lashes Eyelash Serum

Last in the ranking, and the only product here we would ask you not to buy. The published INCI for this variant lists bimatoprost as the fourth ingredient — not a cosmetic analogue, but a licensed prostaglandin medicine that in the UK is prescription-only.

Tested by the Growth Lash Serum panel · 12-week trial · Last reviewed 13 August 2026 · How we test

Price
£15
Size
3 ml
Cost / month
~£5
Type
Growth serum
Compare all 15 → Read the verdict
Long4Lashes Eyelash Serum bottle
Growth overall score
Prostaglandin analogue: Bimatoprost
6.4
/ 10

Score breakdown

Efficacy
9.0

Very effective — which is exactly the problem.

Safety
2.0

Severely capped: the published INCI lists bimatoprost, a prescription medicine in the UK.

Ingredients
5.0

Thin formula. The medicine does the work.

Value
8.0

£15 for 3 ml — cheap, and that is not reassuring here.

The full review

12-week user trial · INCI read line by line

What is in it

Bimatoprost sits fourth, ahead of the hyaluronate and panthenol. Bimatoprost is the active in glaucoma eye drops and in the prescription lash product Latisse. In the UK it is a prescription-only medicine, obtained and monitored through a prescriber precisely because it acts on intraocular pressure and pigmentation. A cosmetic sold over the counter is not the intended route.

Full ingredient list

Aqua, Pentylene Glycol, Pentaerythrityl Tetraisostearate, Bimatoprost, Hydrolyzed Hyaluronate, Panthenol, Allantoin, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Disodium Phosphate, Triethanolamine, Methylparaben, Alcohol.

How it performed

Very effective, which is what you would expect from a licensed medicine. Visible change from week four to five, and strong length by week twelve — among the fastest results we recorded. That is not a recommendation.

Who it is for

Nobody, on this basis. If you want what bimatoprost does, speak to a prescriber and get it properly — with a clinician checking your eye pressure and your irises. If you want a cosmetic serum, there are fourteen other products on this list.

What we liked

✓
Very fast, very visible results
✓
Inexpensive

Keep in mind

−
Published INCI lists bimatoprost, a prescription-only medicine in the UK
−
No clinical oversight of eye pressure or pigmentation
−
Thin supporting formula
−
Sold as an ordinary cosmetic
The verdict

Ranked #15 of 15

We rank it last not because it fails but because it works for a reason that does not belong in a product bought off a shelf. If you are already using it, speak to your optometrist. If you are considering it, do not.

6.4
Growth score

Safety note

This product contains Bimatoprost. Prostaglandin analogues are associated with darkening of the eyelid skin, loss of fat around the eye socket and, rarely, permanent change to iris colour. Do not start it if you have glaucoma or ocular hypertension, or use prescribed eye drops, without speaking to a clinician. Patch-test first, photograph your eyes for a baseline, and stop if you notice redness, swelling, darkening or any change to your vision.

We review products, we are not clinicians, and this is not medical advice. Ingredient information was taken from the manufacturer's published INCI list on 13 August 2026 — formulas change and brands sell variants under similar names, so check the pack you are holding. If this page is out of date, email us and we will correct it.