Background
Sarah holds a degree in chemistry with a concentration in cosmetic science. She spent four years in product formulation at two mid-size beauty companies, where she worked on skincare and haircare lines, before transitioning to independent editorial work in 2021.
Her background in formulation gives her a lens most beauty reviewers lack: she reads INCI lists the way a chef reads recipes. She knows what each ingredient does at the molecular level, which compounds interact, what concentrations actually matter, and where brands cut corners or obscure risks behind technical nomenclature.
Before founding The Lash List, Sarah wrote ingredient deep-dives and product analyses for several independent beauty publications. Her work has focused consistently on one question: what is this product actually doing, and is the brand being honest about it?
Why Lash Serums?
In late 2024, Sarah had a bad reaction to a lash serum she had been using for three months. Her eyelids darkened, and her eye doctor told her the serum contained a prostaglandin analogue, something she had never heard of despite her chemistry background. The compound was buried under an obscure chemical name on the label.
That experience led her to research the entire category obsessively. She read FDA filings, dug into cosmetic ingredient databases, talked to dermatologists and ophthalmologists, and spent months mapping out the ingredient lists of every major lash serum on the market.
What she found was troubling: brands routinely burying prostaglandin analogues under names most consumers would never recognize, exaggerated "clinically proven" claims backed by manufacturer-funded studies with tiny sample sizes, and a regulatory blind spot that lets cosmetic products contain pharmaceutical-grade compounds without prescription oversight.
The Lash List started as a Google Doc she shared with friends. It grew into the site you're reading now.
Testing Methodology
Every product in our database goes through the same structured evaluation process. There are no shortcuts and no exceptions, regardless of brand reputation, price point, or popularity.
Ingredient Analysis
Full INCI breakdown of every active and inactive ingredient. Cross-referenced against the EWG Skin Deep database, CIR safety assessments, and published dermatological research. Prostaglandin analogues are flagged by chemical name, even when brands use obscure nomenclature.
Clinical Evidence Review
We review every clinical study cited by the brand. We check sample size, study duration, whether the study was independent or manufacturer-funded, and whether the results support the marketing claims. Undisclosed or weak evidence is noted.
Hands-on Testing
Each serum is tested by our panel over a minimum of 12 weeks. We document results with macro photography at 2-week intervals. All testers have different skin types, lash types, and sensitivity levels. Products are purchased at full retail price.
User Review Aggregation
We analyze consumer reviews across verified platforms (Sephora, Ulta, Amazon, brand sites) to identify patterns: common complaints, reported timelines, sensitivity reactions, and long-term satisfaction. We weight verified purchases more heavily.
Scoring Criteria
Every product is scored across six weighted criteria. The weights reflect what matters most for consumer safety and satisfaction:
- 25%Ingredient Safety - Prostaglandin status, clean formula assessment, ophthalmologist testing, known irritants, regulatory flags.
- 25%Effectiveness - Clinical data quality, before/after evidence, growth timeline, real user-reported results across multiple platforms.
- 15%Value for Money - Price per mL, cost per month of use, bundle discounts, subscription savings, supply duration.
- 15%User Reviews - Star rating, review volume, consistency across platforms, verified purchase ratio, real user photos.
- 10%Brand Transparency - Full ingredient disclosure, published clinical data, honest side effect warnings, company responsiveness.
- 10%Ease of Use - Applicator design, application frequency, compatibility with contacts and extensions, drying time, formula texture.
The full methodology, including how we handle ties and edge cases, is published at Our Methodology. We believe that if you can't check our work, you shouldn't trust it.
Safety Scoring System
Our safety assessments follow a three-tier system based on ingredient profiles:
- Excellent (prostaglandin-free): No prostaglandin analogues or derivatives detected. Clean formula with well-researched, low-irritation ingredients. These products rely on peptides, plant extracts, biotin, and other growth-supporting compounds.
- Moderate (prostaglandin-containing): Contains one or more prostaglandin analogues (isopropyl cloprostenate, dechloro dihydroxy difluoro ethylcloprostenolamide, or similar). These carry documented risks including iris color change, periorbital fat loss, and eyelid darkening. Effective, but with trade-offs consumers should understand.
- Low (prescription only): Requires a doctor's prescription. Contains bimatoprost (the active ingredient in Latisse), which is FDA-approved but carries the highest documented risk profile of all lash growth compounds.
Editorial Independence
No brand has editorial influence over our content. We buy every product at full retail price. We do not accept free samples, gifted products, or sponsored review placements. Some links on the site are affiliate links, meaning we may earn a commission if you make a purchase. This never affects our rankings, scores, or editorial content. For full details, see our Affiliate Disclosure.
Contact Sarah
Have a question about our methodology, an ingredient analysis, or a product you think we should review? Reach Sarah directly at hello@thelashlist.com.