Home/Ingredient glossary
Eyebrow serum ingredients, graded by evidence
Every growth-related ingredient we have found in a brow product, with what the published research supports. Grades: Strong (controlled trials), Moderate (small trials or consistent results), Weak (mechanism only), None (no evidence of growth).
Isopropyl cloprostenate
Prostaglandin analogue
Extends the growth phase of the follicle. The most potent class of cosmetic actives. Documented risk of skin darkening and eye irritation; not recommended in pregnancy.
Some fast-acting serums; check the INCI list
Bimatoprost (prescription)
Prostaglandin analogue
The licensed lash-growth drug, used off-label for brows. Clinical trials support efficacy; same side-effect profile as other analogues.
Prescription only; not in retail serums
Minoxidil 2–5%
Vasodilator
Small trials show brow regrowth. Must be continued indefinitely; misapplication grows hair where it lands.
Off-label scalp products
Myristoyl pentapeptide-17
Signalling peptide
Stimulates keratin production in the follicle. Small trials show longer lashes; well tolerated with few irritation reports.
Many peptide brow and lash serums
Biotinoyl tripeptide-1
Signalling peptide
Strengthens anchoring of the hair in the follicle, reducing shedding. Modest growth effect alone; usually paired with other peptides.
Peptide serums, often paired with other peptides
Redensyl (DHQG + EGCG2)
Plant-derived complex
Manufacturer-funded trials show scalp hair gains. Brow-specific data is limited.
Some plant-based growth serums
Caffeine
Stimulant
Plausible mechanism from scalp studies; no brow data. Probably harmless, probably inert at cosmetic concentrations.
Many budget serums
Biotin (topical)
Vitamin B7
Oral biotin helps only in deficiency. Topical biotin has no evidence for growth; it is a marketing ingredient.
Most "growth" gels and pencils
Panthenol, hyaluronic acid
Conditioners
Condition hair and skin. No effect on hair count. Useful for feel and for reducing breakage of existing hairs.
Nearly all serums and gels
Castor oil
Conditioning oil
No credible evidence of new growth. Darkens and conditions existing hair, which can look fuller.
Castor blends, generic oils
Reading a brow serum label
Ingredients are listed by concentration. If the first active appears after the preservatives (phenoxyethanol, sodium benzoate), it is present at under 1% and unlikely to do much. Prostaglandin analogues work at tiny concentrations and legitimately appear near the end; peptides usually need to sit above the preservatives to match the concentrations used in trials.
Brands rarely disclose percentages. When two serums list the same peptide, the one with a published concentration or a clinical study on the finished product is the safer bet.