Lash and Brow Thinning With Age: What the Studies Actually Measured

The short version

• Lashes and brows do thin with age. It has been photographed and measured, not just claimed.
• Sudden, patchy or one-sided thinning is a GP question first. No product replaces finding out why.
• Lash serums split in two: prostaglandin analogues, prescription medicines here that we do not supply, and cosmetic serums.
• Evidence for cosmetic serums is weaker than the marketing suggests, and none of it was measured on the products we sell.
• We sell RevitaLash Advanced and RevitaBrow Advanced. The only reliable answer about what is in them is the pack's ingredient list.

The thinning is real

Researchers photographed and digitally analysed the upper lashes of 179 healthy women. Adjusted for race, length, thickness and darkness all declined significantly with age. Mean length ran from 7.98 mm in the 22 to 29 year olds down to 6.39 mm in the 50 to 65 year olds (Glaser, 2014).

Two caveats. The author affiliations include Allergan, Inc., which sells a lash product. And it compared different women at one time rather than following one woman as she aged.

Not all thinning is ageing

Loss of brow or lash hair has varied causes, and accurate diagnosis is the first step in clinical management (Nguyen, 2023). Sudden, patchy or one-sided loss is a doctor's job, not ours.

Two categories, routinely confused

A 2024 review splits the market into prostaglandin analogues and non-prostaglandin analogues. It notes that under United States law, no efficacy or safety assessment by the Food and Drug Administration is required before these products go on sale (Baiyasi, 2024).

That is American law, and we have not checked New Zealand's. Either way: read the ingredient list, not the box front.

The prescription side, which we do not sell

Bimatoprost 0.03% is a prostaglandin analogue, originally a glaucoma medicine, and a prescription medicine here. We do not supply it and are not its sponsor, so no response rates from us. The shape of the research:

• The lash work was multicentre, double-masked, randomised and vehicle-controlled, over two six-month periods (Glaser, 2015).
• It wears off. In idiopathic thinning, effects lasted about two months after stopping and were markedly diminished by four to six months.
• Early brow work was small: a double-blind, vehicle-controlled study in 20 people, called a pilot in its own title (Beer, 2013). Larger brow trials came later, over seven months (Carruthers, 2016).

The eye effects, plainly

• A pooled analysis of six double-masked trials, 680 people on bimatoprost, 379 on vehicle, listed conjunctival hyperaemia, eyelid itching, eyelid pigmentation, eyelid redness and punctate keratitis as common, mostly early, mild, local and reversible on stopping (Wirta, 2015). Four of the nine authors are from Allergan, Inc.
• Prostaglandin-associated periorbitopathy has no agreed grading scale. A 2024 review by glaucoma specialists across Asia was convened for that reason (Liu, 2024). Nobody can honestly quantify a condition nobody can grade.
• A safety re-appraisal found the lash literature dominated by industry-sponsored trials, with design choices that may have under-reported discomfort and periorbitopathy, and iris pigmentation risk inadequately investigated (Steinsapir, 2021).
• In nine glaucoma patients who stopped their drops, a deepened upper eyelid sulcus and reduced eyelid fat pad had improved a year later (Abalo-Lojo, 2023). Nine people is a case series, and the authors call that regression partial.

What the cosmetic serums have behind them

These are sold for the look and condition of lashes, not as medicines. Labels we have read list peptides, panthenol, biotin, glycosaminoglycans and botanical extracts. The 2024 review's verdict: the data are promising, but more studies are needed because of a lack of formal evidence for these ingredients in eyelash serum use (Baiyasi, 2024).

The typical supporting study: 30 women aged 25 to 65 used a peptide and glycosaminoglycan serum for twelve weeks. Length was up 8.3% and volume up 14.1% against their own starting point, with no adverse effects reported (Fernandez-Gonzalez, 2024).

Now read the design. Open label, thirty women, no control group, no blinding, everything measured against their own baseline. Two of the three authors are from Cantabria Labs' medical affairs department.

The serum tested was a Spanish company's, not the products we sell, so those percentages belong to nothing on our shelf.

What is actually in the pack

Cosmetic lash products sometimes contain prostaglandin-related compounds, not always declared. Of 64 eyelash serums bought from 34 websites in Japan, four contained bimatoprost, three of those four undeclared, and eight contained other prostaglandin F2-alpha analogues (Rahman, 2022).

Formulations change, so we will not say from memory which category our products sit in. Ask us for the box.

What to actually do

• Sudden, patchy or one-sided loss goes to your GP first, before any product.
• Apply to a clean, dry lash line. Not into the eye.
• Stop if you get redness, itching or discomfort. See a doctor if it does not settle.
• With any eye condition, or in pregnancy, ask a doctor first.
• The study above ran twelve weeks, so that is the window it covers. That describes research, not what you will see.

No trial we can find puts a cosmetic serum head to head against a prescription option, so we cannot say which does more.

Come and see us in Parnell. We would rather be honest than sell you the same thing twice.