Lash growth serums can do wonders, as usual in beauty, it’s complicated. We asked doctors and lash specialists to weigh in on the pros and cons. Read on for our edit of the best

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It’s hard not to get addicted to the fluttery lushness an eyelash serum can bring about. Depending on the formula, the results can be spectacular, transforming even the sparsest of lash lines. In some cases, they make lashes grow so long they start clashing with their users’ specs. One butterfly-lashed fellow beauty journo (at Vogue, no less) likes to describe hers as ‘camel-like’.

These serums are also a way to hold back the years: as we age, our lashes, like the hairs on our head get sparser and shorter and become yet another sneaky thing that gives our age away.

A number of ingredients have been shown to make lashes grow faster, increase their level of pigment (making them look darker) and/or turn them glossier and stronger, but they all have their own benefits. Some, unfortunately, have potential side effects as well.

With new serums being launched at a rate of knots - even Olaplex has just joined the fray with an innovative new bond-building lash formula, Olaplex Lashbond Building Serum, £64 launching at Space NK on 6 April 2023 - it’s worth having a closer look at how these ‘lash fertilisers’ work and what’s right for you. We turned to some of our favourite medics and lash technicians to weigh up the good and the not so good.

Lash-boosting ingredients: the pros and cons

There are four types of lash-boosting ingredients and your lash serum may contain some or all of them.

Firstly, there are medical and semi-medical serums containing synthetic ingredients called PGAs (prostaglandin analogues). These have clinically proven lash boosting powers and work by keeping the lashes in the growth phase for longer, resulting in thicker-looking, longer lashes. Revitalash , £110 and Rapidlash , £31.35 are the best-known examples.

Then there are ‘skincare active’ lash boosters with peptides. These strengthen the hair follicles, rather like peptide-based scalp serums , which are increasingly popular solutions for thinning hair.

Thirdly you’ll find botanicals and vitamin-based lash serums that work rather like your skincare to nourish and protect.

And lastly castor oil, a traditional remedy also used for hair and brow growth.

Here are the pros and cons of each.

Medical-strength lash boosters: prostaglandin analogues AKA PGAs

PGAs are proven to cause a lash growth spurt and darken lashes; they are synthetic copies of hormone-like chemicals in the body. Their lash-enhancing ability was discovered by accident: it was a side-effect observed in people who were treated for the eye condition glaucoma with an ointment containing a prostaglandin analogue called bimatoprost. It inspired the creation of Latisse as a dedicated lash growth serum.

Like any hair on our bodies, lashes have a growth cycle of three phases: growth, resting, and shedding. A typical lash cycle lasts 30 to 45 days. A PGA treatment keeps the lash in the growth phase for longer and shortens the falling-out phase, effectively accelerating the hair cycle. When you stop, the lashes eventually continue with the normal cycle.

Originally the technology was (and remains) licensed for medical conditions, where lashes fell out, but soon enough, lash lovers latched onto it for cosmetic reasons. The hitch? Bimatoprost remains a drug, so Latisse, which is called Lumigan in the UK, is only available on prescription. The use (and side-effects, see below) is monitored by doctors.

When the first non-prescription lash serums launched it was to great acclaim, because they worked a treat, because they contained PGAs with the same lash-enhancing benefits, but at a level low enough to avoid ‘drug’ status. Cosmetic serums are not monitored by doctors in the way that Latisse is.

When, in 2015 and 2017 respectively, countries such as Canada and Australia outlawed them all together in cosmetics on account of their potential side effects, many brands switched to entirely new PGA-free lash growth formulas.

But you can still buy PGA formulas in the UK and many other countries, and it’s these that are behind the success of Revitalash and Rapidlash, often tipped as the most effective lash serums of all.

“If you want to know whether your serum contains PGAs, look for ‘prost’ in the names of the ingredients on your INCI list,” says ophthalmologist, oculoplastic and reconstructive surgeon Dr Rachna Murthy . Spot something like ‘isopropyl cloprostenate’ and you’ve hit the jackpot.

What are the potential side effects of PGA lash growth serums?

The one most often-cited issue is that the active ingredient can darken your eye colour, permanently. Not a great selling point, but to put into context, this side-effect was noted when using it to treat glaucoma, in the form of eye drops directly on the eyeball as opposed to painted along the lash line, and only in a small number of cases. A darkening or staining of the eyelid has also been observed in rare cases.

More common is irritation. “We see hyperpigmentation, inflammation and redness of the eye line and lid as a result of lash serums with PGAs,” says Murthy. “Also, the additional lash growth can harbour more bacteria, upsetting the delicate microbiome of the eyelid skin. This can result in the eyelid oil glands getting plugged, leading to dry eye disease (scratchy, sore, teary eyes).”

And she isn’t done yet. “With continued use, PGAs can lead to a deep crease in the upper eyelid, droop of the upper eyelid, decreased prominence of the lower eye socket fat pads, and a sunken eye appearance.”

That’s an unpleasant list to be aware of, though Revitalash points out that their product has been independently shown safe to skin and eyes and poses no local or safety risk to eyes when used as directed. For Revitalash, that means using a fine swipe of serum at the base of the lashes, making sure it doesn’t seep into the eye, and no more than once a day. Other PGA serums have similar, though not always quite as concise, instructions.

Like medical hair growth ingredient Minoxidyl, PGAs only work for as long as you use them, so Revitalash and its ilk advise using their products continuously for ongoing results.

Lash extension expert Camilla Kirk-Reynolds  has seen countless sets of royal, celebrity and just plain old ordinary people’s eyelashes close-up over the years. Her priority is lash health; so what does she think of PGA lash growth serums, which many of her clients have used?

“When using these serums, the lashes shed en masse, creating clearly noticeable, gappy areas along the lash line where the younger and therefore shorter lashes are,” she says. Basically, because PGAs push hairs into the anagen (growth) phase, all the lashes will grow and then shed at the same time if you use them long enough, unlike nature’s cycle which has all your hair developing and falling out at staggered intervals.

Kirk-Reynolds also points out that PGA serum-boosted lashes are “an unnatural length and often poker-straight – much more so than average natural lashes.” Her main concern is how long this situation can persist: “Depending on how long people have used these serums, I’ve seen these side effects last months or even years because the active compound seems to stay in the system.”

Can you use lash serums after chemotherapy and hair loss?

Dr Fiona McCarthy , who is qualified both as an oncologist and an aesthetic doctor, says there is no reason why patients can’t use Lumigan or even Revitalash and its if they’ve lost their lashes through treatments such as chemotherapy.

“However, it’s probably best to wait a month or so post-treatment, until the natural lashes start to show. Because of the lack of lashes during chemo, the eye can become very sensitive and irritated, so patients need to be aware that any lash serums may cause a mild irritation initially,” she says.

Our conclusion? PGA-based serums live up to their lash-growing promises. But if you experience irritation (which not everyone does), it’s best not to persist. And even if you don’t, we would advise not applying them constantly, but rather as a bi-annual ‘booster course.’

The ‘skincare’ lash boosters: peptides

Nowadays most lash growth serums feature a blend of peptides as an alternative to PGAs, although you might see them in combination. Peptides are widely used in skincare  to boost collagen and, it is claimed, capable of supporting lash growth in the follicle. “They act in more of a ‘conditioning’ manner,” says Murthy, fortifying and thickening lashes and preventing breakage. There are many peptides, and many combinations of them are used in different serums, some with more success than others, depending on who you might ask.

Peptides generally don’t present with the same proven boosting benefits or potential drawbacks as PGAs, but, says Murthy, “some lipopeptides (a class of peptides connected to a lipid) can irritate as well.”

As can other ingredients often lurking in lash serums, such as alcohol, Murthy advises studying your INCI list intently. This is also worth it because serums that play up their peptide ingredients can feature a prostaglandin analogue too that they perhaps don’t shout about. If you want to avoid them – or indeed embrace them - you need to read the packaging closely.

The lash health boosters: vitamins and botanical extracts

As they do in skincare, vitamins, plant extracts and proteins soften, nourish and provide antioxidant protection, boosting skin health but also healthy hair growth. You’ll find lash serums with ingredients such as biotin, panthenol (vitamin B5) and hydrolysed keratin, which are also staples in hair supplements and fortifying haircare.

Skincare favourites such as vitamin A and vitamin C f eature as well, alongside clover flower and ginseng root extracts that help prevent hair loss. Additionally, you’ll find humectants such as hyaluronic acid and sorbitol to hydrate brittle lashes. None of these help the hairs grow faster or longer, just stronger. They pose no risk in and of themselves and are often combined with peptides and/or PGAs for a 360-degree better-lash effect.

The lash nourisher: castor oil

Long used as a traditional remedy for thinning hair and brows, castor oil is a popular lash booster. “The oil is rich in essential fatty acids, vitamin E and other nutrients,” says consultant dermatologist Dr Anjali Mahto . “It creates a barrier that locks in moisture and increases cell metabolism, thus promoting hair growth.”

As always, this may be a natural remedy but that doesn’t mean it’s devoid of side effects. “Repeated, the excessive application can irritate the skin, and grapeseed extract, a potent natural preservative sometimes added to castor oil, can cause the skin to become inflamed,” says Mahto.

Murthy agrees and advises caution when applying any lash-conditioning oil (you’ll find olive and jojoba oils in lash conditioners, amongst others, for their fatty acids and moisturising benefits). “Oil too close to the eyelid margins can migrate onto the eyes. It can promote bacterial growth and result in disturbance of the microbiome,” she warns.

You should also be warned if you have lash extensions - most extension adhesive degrades when in contact with oil, so you’ll need to steer clear.

The bottom (lash) line

Do lash serums work? The good news is that many do. But the lash health experts, we’re afraid, are no fans, although they don’t go so far as to say you must never use them. Murthy says that not everyone experiences side effects, or serious ones from PGAs, and points out that under medical supervision, Lumigan can be a great help for those who’ve lost their lashes through things such as chemotherapy.

Kirk-Reynolds says that lash extensions don’t work particularly well on lashes grown with the help of PGA-based serums. She advises being very circumspect and quitting your habit if you notice any irritation at all.

Brands advise using PGA-based serums once a day for at least two-to-three months to see full results, then two or three times a week to keep your lashes going. But keeping some of the potential side effects in mind, we’d advise using a tube (which lasts two-to-three months) occasionally for a special occasion, and switching to a nourishing peptide-based growth serum the rest of the time.

What is the expert’s best advice for thicker, fuller lashes?

Kirk-Reynolds suggests improving your diet and taking supplements: “In my opinion it’s the very best thing you can do to promote lash growth. Biotin, selenium and horsetail especially can make a difference,” she says.

For Murthy “prevention is better than cure. Avoid astringent eye makeup removers (some contain alcohol) and instead use gentle micellar water which doesn’t dry the eyes and lashes,” she says. “Change your mascara every three months [how annoying!] as the preservatives in the makeup can be formaldehyde-based which damages the eye surface and follicles.”

She advocates improving eyelash condition by encouraging natural oil production in the lash follicle rather than adding oils.

Tools and treatments for lash growth

At Murthy’s Face Restoration clinic , she and her fellow eye surgeon Dr Jonathan Roos  are introducing Optilight, a device that uses intense pulsed light (IPL) to gently encourage oil gland function.

It treats dry eye disease but also promotes healthy lashes. If that sounds rather too costly, we are fans of the Get the Gloss 2021 Award-winning Peep Club Heated Eye Wand , £60 , which aids oil production in the lash lines with gentle heat, sonic vibration and LED light. It’s a world away from lash serums, but it may be the most sustainable option for your eyes and lashes.

Our pick of the best lash boosters

We selected our favourites with different lash-boosting ingredients. Our edit is chosen independently, but if you choose to buy something we feature we may earn affiliate commsiion.

Best hi-tech serum for thicker lashes: Olaplex Lashbond Building Serum, £64

What stands out about this predominantly peptide-based serum is that the peptides are really high up in the formula, which gives them a much greater chance of actually working. The preservative appears very low, which is also a good sign that this swipe-on formula contains lots of useful ingredients (panthenol, biotin, soothing oats, humectants), and limits the chances of irritation. Inspired by Olaplex’s bond-building innovation (but not actually using that same technology), this has two peptide complexes: one supports lash line health to encourage unhampered growth, while the other boosts both the lash growth cycle and lash retention for a significantly fuller flutter, which was reported by 100% of testers in the brand’s own clinical study. All that, and it’s vegan too.

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Best multi-peptide lash serum: Beauty Pie Lash Fuel Advanced Peptide Serum, £19.50 (members)/£70 (full price)

This vegan Korean formula, which you swipe along the lash line, makes big promises: significantly longer lasher in two weeks, and significantly thicker ones in four, according to clinical trial-outcomes. It certainly has plenty of growth-supporting peptides (five of them), although this does include a lipopeptide which may irritate some skins (annoyingly, it does mine). Trusted lash nourishers panthenol and biotin are also here, alongside hydrators, cell energisers and prebiotics to keep the lash line healthy and thriving: they’ve thought of everything!

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Best vegan lash serum: Kosas GrowPotion, £40

With a fairly unique 2-in-1 sponge applicator that can be used on both brows and lashes, the formula contains vegan keratin that will condition but not boost growth, hydrating hyaluronic acid, pro-vitamin B5 and three types of peptides. There is no prostaglandin in this serum, but it has been clinically measured and tested. The results showed 97 per cent of the 29 people in the study trying the serum had improved brow length and lash volume.

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Best for fast, dramatic lash growth: Revitalash Advanced Eyelash Conditioner, £110

Few eyelash serums have more ardent fans than this one, which throws in a PGA, peptides, biotin, ginseng extract, plant proteins and just about everything else that might (or will) make lashes grow. And it tends to do it faster than any other serum. Can be pretty stingy on application, though – if that won’t quit, don’t persist.

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Best for long lashes that won’t break the bank: Rapidlash Eyelash Enhancing Serum, was £39.99 now £29.40

In the battle of Revitalash vs Rapidlash, which comes out on top? Given that this is another everything-and-the-kitchen-sink lash serum (yes, it features a PGA), it’s a close-run thing; we know at least one colleague (at Vogue magazine, no less) whose ‘camel lashes’ attest to this stuff working exceedingly well. And it’s half the price of ‘the other one’.

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Best for lashes AND brows: Typology Eyelashes & Brows Serum 2% Pea Peptides & Castor Oil, £16.90

Based on (vegan) pea peptides, castor oil and a biotin-peptide compound, this won’t grow your lashes as dramatically as prostaglandin formulas but they will get stronger, thicker and longer eventually. Applied with a spoolie, you brush it through lashes as opposed to painting it on the lash line, making it work just as well on your brows.

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Best plant-based lash growth serum: Natucain Lash Serum, £59

This is a plant-based (and PGA-free) serum with a difference: instead of the usual vitamins and fortifying botanicals, it has a patented molecule made with bamboo, thyme and lentil (Green Goddess salad, anyone?) stem cells. It’s said to inhibit the synthesis of the DHT hormone responsible for hair loss and thinning, and trigger a growth factor that helps more hair to sprout. It means the the hair growth (anagen) phase of the lashes is extended, much like in the case of PGAs, but without the potential irritation. The product is high in alcohol (as often in formulas with high levels of plant extracts), but reports about the serum’s efficacy (there’s a hair and a brow growth booster with the same formula) have been good.

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Best for lash extension-wearers: Clinique High Impact Lash Amplifying Serum, £36

This new oil-free serum is a riot of humectants, peptides and amino acids (the building blocks of peptides and keratin) alongside clover and ginseng extracts, all shown effective as lash fortifiers that aid healthy growth. Your lashes will grow following their natural pattern and curl (just a stronger and more voluminous version), ensuring that they work well with lash extensions.

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Best budget lash growth serum: Maybelline Lash Sensational Boosting Serum, £14.99

Boasting a lash-boosting combo of amino acids and provitamin B5, this won’t make your lashes hit your eyebrows but people we know and trust swear it has thickened and lengthened theirs, which is good going at the price. Comes with another precision mascara wand so you can try it on your brows (yes not officially, but it’s perfectly safe).

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Best serum for glossy lashes: BBB London Luscious Lash Oil, £22

Revitalash vs castor oil: which is best here? Well, Revitalash for sure, if you want those big, bold lashes in a flash. But for conditioning with no drawbacks, this blend of apricot kernel, jojoba and castor oil plus strengthening botanicals is the right choice. Applied like mascara, it lets you avoid too much product on the lash line so as not to overload it and cause clogging. Don’t use it every day, just regularly to keep your lashes healthy.

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There is no doubt that PGA-based serums are unrivalled for getting seriously longer and darker lashes, fast, but it’s essential that you use them correctly. If you have a little more patience and like the idea of long-term fuller, stronger and somewhat longer lashes, opt for a conditioning peptide-based serum. A lash oil is a good conditioner as well, but use it sparingly so as to avoid overloading and clogging the lash line.