Petrolatum

Overview

Petrolatum, also called petroleum jelly or by the brand name most people know, is a semi-solid mixture of long-chain hydrocarbons derived from refined crude oil. Cosmetic-grade petrolatum (USP or BP standard) has been multi-step refined to remove the polycyclic aromatic hydrocarbons (PAHs) that are present in industrial petrolatum and which carry health concerns. The cosmetic grade is, by every reputable measure including IARC, considered safe and non-comedogenic.

It is the single most studied moisturising ingredient in dermatology. The evidence base for its barrier-repair effect is genuinely large. It is the ingredient recommended by every major dermatology association for severely dry skin, eczema, post-procedure recovery, and overnight slugging.

It comes as a thick, semi-solid, almost odourless, clear-to-amber jelly with a melting point around 40 C. Storage is essentially indefinite — petrolatum does not oxidise, does not feed microbes, and does not lose function on a shelf.

What it does in a formula

The defining property: petrolatum is the most effective occlusive ingredient available. Measured by transepidermal water loss (TEWL) reduction, petrolatum cuts skin water loss by 98-99% — higher than any other emollient or oil. Lanolin, the second strongest, sits around 50-70%.

That occlusive power has two consequences:

• Skin repair acceleration. Sealing in water lets the skin barrier rebuild itself. Petrolatum is consistently used in clinical studies as the positive control because nothing beats it for raw barrier repair.
• No active skincare benefit beyond the seal. Petrolatum does not penetrate the stratum corneum. It sits on top. It is not “feeding” the skin anything — it is just preventing water from leaving.

It is also non-comedogenic in modern testing (older comedogenicity rankings were based on rabbit ear assays that did not predict human comedogenicity well). Petrolatum does not clog pores.

How to use

Add to the oil phase. Melt gently — 40-50 C is plenty. It melts cleanly and incorporates easily.

Usage rates by product type:

• Overnight “slugging” treatments: 90-100%
• Lip balms (severe chapping): 20-80%
• Hand and foot rescue balms: 20-60%
• Eczema barrier balms: 10-40%
• Diaper rash creams: 30-60%
• Body butters for very dry skin: 10-30%
• Face creams (light barrier support): 2-8%
• Cuticle treatments: 50-90%

For overnight slugging, pure petrolatum (or a 90% petrolatum + 10% squalane blend for a less heavy feel) is the standard. Layered over a humectant-rich moisturiser, it seals in everything underneath.

Best for / Worst for

Best for: eczema, atopic dermatitis, severely dry skin, hand and foot rescue, cracked heels, chapped lips, post-procedure recovery (especially over fresh tattoos, laser treatments, microneedling — under medical guidance), diaper rash, overnight slugging, winter dry weather.

Worst for: brands positioned as “natural” or “clean” (the petroleum origin triggers strong objections in those markets, even though the science supports safety), oily skin used as a daytime moisturiser (it feels heavy and traps sebum), people who genuinely break out from heavy occlusives (rare, but real for some skin types), products marketed to environmentally conscious customers (the petroleum sourcing is part of the objection).

Common pitfalls

Confusing it with industrial petrolatum. Cosmetic-grade USP/BP petrolatum is multi-step refined and PAH-free. Industrial-grade petrolatum (the stuff used as a machinery lubricant) is not the same product. Always buy cosmetic-grade.

Marketing it as “moisturising” when it is “occlusive.” Petrolatum does not add moisture. It seals in moisture that is already there. If you apply it to bone-dry skin without a humectant underneath, it will lock in the dryness. Always layer over a damp surface or pair with humectants in the formula.

Buying into older comedogenicity scares. The original comedogenicity studies that ranked petrolatum as “clogging” were done on rabbit ears in the 1970s. Subsequent human studies have shown petrolatum to be non-comedogenic. If a customer asks, share the modern evidence.

Sustainability and ethics positioning. Petrolatum is a fossil-fuel-derived ingredient. Some customers will reject it on principle, and that is a legitimate brand decision. For brands that want the performance without the petroleum origin, plant-based alternatives exist but do not match the occlusive strength exactly.

Substitutes

• Lanolin — second-strongest occlusive, water-binding, animal-derived.
• Squalane + beeswax blend (50/50) — plant-based alternative, roughly 70% as effective as petrolatum for TEWL reduction.
• Castor oil + beeswax + cocoa butter blend — fully plant-based balm structure, slower but real barrier effect.
• Shea butter at high rates (40-60%) — natural alternative for “balm” applications.
• Hydrogenated castor oil (Castor Wax) — plant-derived semi-solid, denser feel.