Petrolatum

Petrolatum is a purified mixture of hydrocarbons used as an occlusive film-former. In disrupted skin it markedly reduces transepidermal water loss and speeds recovery of barrier function compared with untreated sites[1].

What it does

By forming a water-impermeable film it keeps endogenous water in the stratum corneum while lipids reorganise. That is why it anchors repair creams (including ceramide systems such as ceramide NPCeramide NPModerateCeramide NP · Sphingolipid (non-hydroxy fatty acid, phytosphingosine)The most abundant ceramide class in the stratum corneum; topical replacement improves barrier in controlled trials.Open in the Index →) and why the FDA lists white petrolatum as an OTC skin protectant[2].

The evidence

Classic barrier-disruption work showed petrolatum-treated sites recovered faster than untreated controls[1]. CIR has assessed petrolatum as safe in cosmetic use when polycyclic aromatic hydrocarbon specifications are met[3].

How to use it

Best as the outer layer on dry or compromised skin, or mid-formula in creams. Cosmetically heavy; lighter silicones such as dimethiconeDimethiconeStrongDimethicone · Linear polydimethylsiloxaneLightweight silicone occlusive/emollient and FDA OTC skin protectant; reduces TEWL with less greasiness than petrolatum.Open in the Index → are often preferred for daytime face use.