Hexanediol is a mild, water-loving skincare liquid that works in the background rather than as a rejuvenation active. It draws water to the surface for a modest, short-lived plumping feel, helps proven ingredients penetrate, and enables gentler, better-preserved products. These benefits are real but indirect, and the supporting evidence is thin. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Skin surface hydration (corneometer) | >40 a.u. | Tracks whether the humectant benefit is real and sustained |
| Transepidermal water loss (TEWL) | <15 g/m²/h | Indicates barrier integrity; flags barrier-loosening or over-exfoliation |
| Visible irritation / erythema | None to minimal | Detects stinging, redness, or reaction from the ingredient or co-formulated actives |
Cadence: Baseline before starting, then ~2 weeks, 6–8 weeks, and every few months thereafter