Cited skincare — every flag names its source, no upsell.
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Petrolatum

PetrolatumBarrier

The most studied occlusive in dermatology. The 'slugging' trend rests on this molecule.

What it does

Petrolatum is the most-studied occlusive in dermatology. It does not work as a surface seal. In controlled human testing it permeated the spaces between cells at every level of the skin's top layer. Barrier recovery sped up rather than slowing down. Pharmaceutical-grade petrolatum is non-comedogenic in well-designed studies. Used as the final layer in 'slugging' routines, on chapped lips, and in compromised-barrier rebuild protocols. No pregnancy concerns have been raised for it in the literature, though it has not been studied in pregnancy specifically.

The evidence, graded

strongPetrolatum is the most-studied occlusive in dermatology, but it does not act as an impermeable film. It permeates the spaces between skin cells at every level of the stratum corneum and speeds barrier recovery rather than delaying it.Ghadially 1992 · Journal of the American Academy of Dermatology ↗
emergingHyaluronic acid and other humectants work by binding water — they need a water source to hold. On bare-dry skin in very low humidity, an unsealed humectant layer can lose its bound water to the air, so HA alone may feel like it does little (or leave skin tight) rather than hydrating. Apply HA on damp skin and seal with an occlusive layer so the bound water stays in the skin.Papakonstantinou 2012 · Dermato-Endocrinology ↗

Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.

Also known as

petroleum jelly, vaseline

Pairs worth knowing

Ceramides · works together ↗Glycerin · works together ↗Hyaluronic Acid · works together ↗

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