Which is the best lash serum for long, healthy eyelashes?

It’s hard not to get addicted to the fluttery lushness that a lash growth serum can create. Depending on the formula, the results can be spectacular, transforming even the most sparse lash lines. Lash serums are also a way to hold back the years: as we age our lashes, like the hairs on our head, become sparser and shorter.

A number of ingredients have been shown to make lashes grow faster, increase their pigment, making them look darker, and/or make them glossier and stronger.

Some have potential side effects as well, so we turned to some of our favourite medics and lash technicians to weigh up the good and the not so good, and help you find the right lash booster.

What are the most common lash-boosting ingredients?

Your lash serum may contain some or all of the following:

• PGAs or prostaglandin analogues are synthetic ingredients that have clinically proven lash boosting powers. They work by keeping the lashes in the growth phase for longer, resulting in them becoming thicker-looking and longer. Revitalash and Rapidlash are the best-known. Some countries have banned PGAs for cosmetic use due to possible side-effects.
• Peptides haven’t got the clinical lash-boosting backing that PGAs have, but they are found in many lash serums as they strengthen the hair follicles, and so result in more luscious hair growth (much like peptide scalp serums).
• Vitamins, plant extracts and proteins such as vitamin B5 and hydrolysed keratin soften, nourish and provide antioxidant protection, boosting skin health but also healthy hair growth.
• Castor oil is a traditional remedy that’s particularly popular in South Asian countries for supporting hair growth in the scalp, brows and lashes.

What are PGAs and how to spot them

Medical-strength PGAs are proven to cause a lash growth spurt and darken lashes. Their lash-enhancing ability was discovered by accident as a side-effect observed in people who were treated for the eye condition glaucoma with a prostaglandin analogue called bimatoprost. The patients’ suddenly-lush lashes inspired the creation of the dedicated lash growth serum Latisse.

PGA treatment keeps the lash in the growth phase for longer and shortens the falling-out phase, effectively accelerating the hair cycle (typically 30 to 45 days) for as long as you use it.

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

Soon, non-prescription lash serums, with PGAs at a level low enough to avoid ‘drug’ status, launched. (Cosmetic serums are not monitored by doctors in the way that Latisse is).When countries such as Canada and Australia outlawed them altogether 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 lash growth serums containing PGAs?

The most common one is that the active ingredient can darken your eye colour, permanently. Not a great selling point, but to put it in context, this side-effect was, in a small number of cases, noted when PGAs were used to treat glaucoma, in the form of eye drops directly on the eyeball, as opposed to painted along the lash line. 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, she says, can result in the eyelid oil glands getting plugged, leading to dry eye syndrome (scratchy, sore, teary eyes).

And that’s not all. Murthy cautions that with continued use, PGAs can lead to a deep crease in the upper eyelid, a droop of the upper eyelid, decreased prominence of the lower eye socket fat pads, and a sunken eye appearance.

Lash extension expert Camilla Kirk-Reynolds meanwhile, has her own observations of long-term PGA serum use, as they are popular with her celebrity clientele.

“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 your hairs developing and falling out at staggered intervals.

Kirk-Reynolds also points out that PGA lash 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 how long people have used these serums she’s seen these side effects last months or even years “because the active compound seems to stay in the system.”

That’s an unpleasant list to be aware of, though Revitalash points out that their product has been independently shown to be safe to skin and 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, no more than once a day. Other PGA serums have similar, though not always quite as concise, instructions.

How long should you use a lash serum with PGAs for?

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

Experts like Murthy and Kirk-Reynolds, however, strongly advise, to only do a two-month course of treatment twice a year at most.

Can you use PGA-based lash serums after chemotherapy and hair loss?

Dr Fiona MCarthy, 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 ilk 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.’

Lash-boosting peptides: the pros and cons

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, are 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.

Peptides generally don’t present with the same proven boosting benefits, nor potential drawbacks, as PGAs, but, says Murthy, “some lipopeptides (a class of peptides connected to an oily molecule) can irritate as well.”

As can other ingredients often lurking in lash serums, such as alcohol, so Murthy advises studying your INCI list intently. Be warned that serums that are presented as peptide-based can feature a prostaglandin analogue that’s not explicitly mentioned. Look for ‘prost’ in the names of the ingredients on your INCI list: ‘isopropyl cloprostenate’  and ‘bimatroprost’ are examples of PGAs.

Vitamins, proteins and botanical extracts for lash growth

These are classic skincare ingredients that protect, soften, and nourish skin cells as well as follicles. 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 C feature 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 a good idea for repairing your lashes after overuse of waterproof mascara or harsh cleansers.

Does castor oil work for lash growth?

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, she says, creates a barrier that locks in moisture and increases cell metabolism, thus promoting hair growth.

This may be a natural remedy but that doesn’t mean it has no side-effects. Mahto warns that repeated, excessive application can irritate the skin. She also notes that grapeseed extract, sometimes added to castor oil as a potent natural preservative, can cause skin to become inflamed.

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.

Oils don’t mix with lash extensions, either, as they will interfere with lash glue.

The bottom line: do lash serums work?

Yes, 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, 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 is of the opinion 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.

We’d advise using a PGA lash serum 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.

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 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. We are fans of Peep Club Heated Eye Wand, £65, which aids oil production in the lash lines with gentle heat, sonic vibration and LED light.