The length of longer eyelashes is genetically determined but can be influenced by cosmetic and nutritional ingredients. Three biological factors influence it: the duration of the anagen phase (active growth, 30 to 45 days on average), the rate of cell division in the follicular matrix, and the quality of the hair shaft’s keratinization—well-structured keratin reduces breakage before natural shedding. Eyelash-lengthening serums act on all three of these factors simultaneously, which explains why it takes 6 to 12 weeks to see results.
Peptides from the Myristoyl Pentapeptide-17 family (the active ingredient in Embryolisse Soin Booster Cils and Garancia Larmes de Phoenix) activate the membrane receptors of keratinocytes by mimicking fragments of laminin-5, an adhesion protein found in the follicular basal lamina. This stimulation increases the expression of keratinization genes (KRT81, KRT86) and moderately prolongs the anagen phase. Randomized, double-blind studies confirm a 25–50% increase in apparent eyelash length after 8–12 weeks at concentrations of 0.1–0.5%.
Topical caffeine (1–3%) inhibits phosphodiesterase, increasing cAMP in perivascular smooth muscle cells—promoting local vasodilation and the delivery of nutrients to the eyelash follicles. Improved vascularization accelerates cell division in the matrix and moderately prolongs the anagen phase, according to in vitro studies on hair bulbs. Vitry ToniCils Pro Expert Serum combines caffeine and peptides to deliver this dual mechanism.
Bioflavonoids (rutin, hesperidin, diosmin) inhibit perivascular hyaluronidase and collagenase, maintaining the integrity of the basal lamina of the eyelash follicle. Their effect on peri-follicular capillary permeability reduces microhematomas that compress the follicles and shorten the anagen phase. When combined with caffeine in a serum, they form the vasoprotective duo found in professional eyelash serums.
Niacinamide (2–5%) stimulates ceramide synthesis in follicular keratinocytes, strengthening the eyelash fiber’s internal lipid barrier and reducing dehydration—a better-hydrated fiber is more resistant to the repeated pulling caused by makeup removal. Dexpanthenol penetrates the eyelash fiber and is converted there into pantothenic acid, which softens the keratin from within, reducing breakage during the telogen phase. The combination of niacinamide and D-panthenol provides the nutritional foundation that optimizes the action of lengthening peptides.
The effectiveness of lengthening serums depends as much on regular application as it does on the active ingredients. Glycerin (3–5% in eyelash serums) maintains moisture in the application area and improves the penetration of active peptides into the follicle. To maximize the effect: apply the serum every evening to the roots of clean eyelashes (after removing makeup, before applying eye cream), using a fine brush or a precise applicator. Never stop using the product before 8 weeks—since the eyelash growth cycle lasts 3 to 5 months, results appear gradually, and stopping prematurely will undo the progress made.
