The best eyelash serum depends on what you want it to do. Some serums condition the eyelash which makes the lashes look glossier and smoother. Others are designed to support actual eyelash growth by acting at the follicle level. Those two categories are often marketed as if they are the same but biologically they are very different.
At Opti Laboratories, we have specialised in eyelash and eyebrow growth since 2007. This guide explains how to tell the difference between a cosmetic lash conditioner, a peptide serum and a clinically proven eyelash growth treatment so you can choose the right option before you buy.
If you want to condition your lashes to help them look softer and smoother then a cosmetic lash serum may be enough. These products usually contain ingredients such as panthenol, hyaluronic acid, peptides, biotin, plant extracts or conditioning polymers. They can help lashes look healthier and may reduce breakage, but they do not have the same level of evidence for measurable eyelash growth.
If you want genuine growth – longer, thicker and darker lashes over time, then the best-evidenced active ingredient is bimatoprost 0.03%. This is the active ingredient used in Latisse in the United States and in our prescription bimatoprost eyelash growth treatment. It has been proven to be safe and effective in controlled clinical studies, and is used through a medical prescribing pathway rather than sold as an ordinary cosmetic over the counter.
In short: the best eyelash serum for conditioning is not necessarily the best eyelash serum for growth. The first protects the hair shaft; the second affects the follicle and growth cycle.
If you already know you want a clinically proven growth treatment, you can read more about the Opti Laboratories Lash Growth Treatment. If you are still comparing options, continue reading.
Eyelashes are small but highly specialised hairs. Once a lash has grown out from the follicle the visible fibre is no longer living tissue. A conditioning serum can coat, smooth and protect that fibre but it cannot change the growth rate of that existing lash.
That does not make conditioning serums useless. They can be helpful if your main problem is dryness, brittleness, UV exposure, mascara damage, lash lift damage or breakage during sleep. A good conditioning serum can improve surface smoothness, reduce friction and make the lashes appear healthier.
Growth treatments work differently. They act at the follicle level. Bimatoprost is a prostaglandin analogue and the mechanism of eyelash growth is believed to involve increasing the proportion of lashes in the anagen growth phase and increasing the duration of that growth phase.
This matters because eyelashes have a naturally short growth cycle. You cannot make a lash genuinely longer overnight. A true eyelash growth serum needs time to influence the follicles and allow new, longer hairs to emerge.
A serious eyelash growth claim should be supported by controlled clinical evidence, not just before and after photographs, influencer videos or vague claims such as “supports fullerlooking lashes”.
The strongest published evidence is for bimatoprost 0.03%. In the Latisse clinical study described in the prescribing information, participants using bimatoprost showed average 16-week improvements of 25% in eyelash length, 106% in thickness and 18% in darkness, compared with the vehicle group.
The same prescribing information states that the effect is gradual. This is consistent with normal lash biology. A serum that promises dramatic structural growth in a few days is usually describing conditioning or cosmetic coating rather than true growth.
Further clinical studies have also supported bimatoprost 0.03% for eyelash growth, including multicentre, randomised and vehicle controlled studies. These studies found significantly greater improvement in eyelash prominence, length, thickness and darkness in the bimatoprost group compared with those using a placebo.
| Serum type | Main purpose | Likely mechanism | Typical timeline | Evidence level | Best suited for |
|---|---|---|---|---|---|
| Cosmetic lash conditioner | Improves lash appearance and condition | Coats, hydrates and smooths the lash shaft | Days to weeks | Poor; often based on client feedback rather than trials | Conditioning lashes only |
| Peptide lash serum | Supports the lash environment and improves cosmetic appearance | May support keratin production or surface condition, depending on formula | 6 to 12 weeks | Very limited compared with bimatoprost | People wanting a basic serum |
| Protective daytime serum | Protects existing lashes from environmental damage | Conditioning, antioxidant and UV-protective support | Immediate cosmetic benefit; longer-term protection with use | Certain serums have been well tested | People wanting to protect their eyelashes to help optimise their appearance |
| Prescription bimatoprost growth treatment | Stimulates measurable eyelash growth | Stimulates and prolongs the hair growth cycle | Visible improvement often begins around 2 to 3 weeks; full assessment around 16 weeks | Controlled, independent clinical trial evidence | People wanting longer, thicker, darker natural lashes |
The growth treatment and the sun protect serum
£169.00
The ONLY clinically-proven growth treatment. Also available for brows.
£120.00 (3 month supply)
The world’s first lash and brow serum to protect from sun damage.
£59.00
Before buying, ask these questions.
If your lashes are dry, rough or brittle, start with conditioning and protection. If they are genuinely short or sparse, you may need a growth treatment rather than a cosmetic conditioner.
Look for controlled studies, objective measurements and specific outcomes. “Longer looking lashes” is not the same as an independently measured increase in length, thickness and darkness.
Cosmetic serums can help the appearance and condition of lashes, but they are not medicines. Bimatoprost is a prescription-only medicine in the UK when supplied as a medicine, and it should be used only after appropriate medical assessment.
The eye area is sensitive. If you have glaucoma, abnormal eye pressure, uveitis, macular oedema risk, recent eye surgery, active eye inflammation, pregnancy, breastfeeding or contact lens concerns, you should seek medical advice before using a prescription eyelash growth treatment.
The best eyelash serum brands do not promise overnight growth. They explain the eyelash growth cycle, set realistic expectations and provide clear aftercare. Opti Laboratories was built specifically around eyelash and eyebrow growth, rather than treating lash serums as a small beauty accessory.
“I lost eyelashes on chemotherapy and was recommended the lash serum by a friend who had also had chemo. My eyelashes have genuinely grown back even longer than they were before they fell out and everyone has been complimenting me on them. They are noticeably long and thick looking. Really highly recommend to anyone who has lost lashes.”
Sophie C, verified buyer
I had chemotherapy last year and have been using the OptiLaboratories Lash Growth Treatment ever since. I can honestly say it’s one of the most incredible products I’ve ever used.
I’ll admit, my expectations were low—we’ve all tried products that promise everything and deliver very little. But this completely exceeded anything I imagined.
My lashes had been significantly affected by chemo and ongoing medication, but since using this treatment, they’ve grown stronger and healthier over time. I now have noticeably longer, fuller lashes, and it’s made such a difference to how I feel.
For the first time in a long time, I feel genuinely confident again”
Claire B, verified buyer
“Have been using the product for many months and it works like magic for eyelash growth – gentle on eyes and surrounding skin. I’ve suggested it to friends and they’re using it as well. The results speak for themselves.”
Sonia P, verified buyer
Our clinically proven, prescription strength growth treatment has been our gold standard treatment since we started in 2007.
Trusted by over 37,000 clients.
Each pack includes the treatment and the applicators, which lasts most people three months with careful usage.
Once any underlying medical or nutritional cause has been addressed, many people want to regrow their lashes and eyebrows.
Opti Laboratories are the eyelash and eyebrow growth experts. We believe that night time behaviours are under-recognised and that simple interventions can make a measurable difference.
Our clients include individuals recovering after:
▪️Thyroid related brow loss
▪️Chemotherapy related eyelash thinning
▪️Trichotillomania and related issues
▪️Cosmetic over plucking
▪️Eyelash and eyebrow loss from radiotherapy
▪️Thinning eyelashes due to medications
However, we also help a lot of people that simply want longer eyelashes and thicker eyebrows too.
Based in the UK and led by a team of British doctors, we have helped thousands of clients. since 2007 and we have been recognised in UK newspapers and magazines.
We continue to innovate. Our award-winning daytime lash and brow serum, the first in the world to offer UV protection for lashes and brows, supports growth and helps protect fragile follicles during your recovery.
This article is intended for educational purposes and does not replace individual medical assessment. Persistent or unexplained eyelash or eyebrow loss should be evaluated by a qualified healthcare professional.
The best eyelash serum for actual growth is one with clinical evidence showing measurable changes in lash length, thickness and darkness. The strongest evidence is for bimatoprost 0.03%, which has been studied in controlled clinical trials and is used through a prescription pathway.
Most ordinary lash serums are conditioners. They can make lashes look smoother, glossier and healthier, and they may reduce breakage, but they do not have the same evidence for follicle-level growth as bimatoprost.
Genuine eyelash growth takes time because the lash cycle is measured in months. With bimatoprost, many users begin to notice visible improvement after 8 weeks, with clinical studies usually assessing full results at around 16 weeks.
Prescription eyelash growth treatments can be safe when used correctly and after medical assessment, but they are not suitable for everyone. People with eye conditions, abnormal eye pressure, pregnancy, breastfeeding, recent eye surgery or allergy to ingredients should seek medical advice before use.
If your main problem is brittleness, dryness or breakage, a conditioning and protective serum may be more appropriate than a growth treatment. Reducing friction, protecting lashes from UV exposure and avoiding harsh makeup removal can all help protect the lash shaft.
Yes, in many cases a conditioning or protective daytime serum can complement a night-time growth treatment. The growth treatment supports follicle-level change, while the conditioning product helps protect the existing lash fibre from dryness, UV exposure and breakage.
