Slugging — how the technique works, who benefits, and when to use it.

Slugging is the practice of applying a petroleum jelly product as the final step of an evening skincare routine, creating a near-impermeable occlusive seal over everything beneath it. The name comes from the shiny, damp appearance it creates on the skin.

The technique became widely discussed after it spread on social media in 2021 and 2022, positioned primarily as a barrier-recovery method. The skincare community's response was split: some practitioners reported significant improvements in texture, hydration, and sensitivity; others reported milia, congestion, and breakouts.

Both responses are predictable. The divergence is explained by the mechanism.

How slugging works

Petroleum jelly is occlusive — it does not absorb into the skin and delivers no active ingredient. What it does is create a physical seal that dramatically reduces transepidermal water loss (TEWL). Under an occlusive barrier, TEWL can be reduced by over 95%. The skin retains its existing hydration, barrier repair processes that occur overnight proceed under maintained moisture, and a compromised barrier can recover more quickly than it would otherwise.

This is the same mechanism that makes petroleum jelly useful in wound-care dressings. It is not coincidental — it is the same function applied to the skin's surface.

The evidence

Petrolatum — the INCI name for petroleum jelly — has the strongest occlusive data of any skincare ingredient. It is non-allergenic and inert; it does not react with or degrade other ingredients.

The claim that petroleum jelly is comedogenic persists in popular skincare discussion. The data does not support this for facial skin across the general population. Petrolatum is rated non-comedogenic in established testing frameworks. The confusion stems from generalising mineral oil data to petrolatum — they are different compounds.

Who benefits from slugging

People with chronically dehydrated or barrier-compromised skin. The mechanism directly addresses these conditions. People managing eczema flares, post-active recovery after retinol introduction, or persistent sensitivity see the most meaningful benefit.

People in low-humidity environments. TEWL is accelerated by dry conditions — heated rooms in winter, air-conditioned spaces in summer. An occlusive layer is most useful when the ambient environment is working against the barrier.

People who have stripped the barrier through over-exfoliation. Slugging is one of the most practical short-term recovery interventions: no actives, maximum occlusion, barrier repair supported.

Who should approach it cautiously

People with acne-prone or congested skin. Petrolatum itself is non-comedogenic, but slugging traps whatever is on the skin beneath it. If pores are not adequately cleared beforehand — or if product buildup exists — occlusion can contribute to congestion. Cleanse thoroughly before slugging. Avoid layering heavy balms or silicone-rich products underneath.

People using retinol. Slugging over a retinol application amplifies its penetration. For adapted skin, this may increase efficacy; for those in the adjustment phase, it significantly increases irritation risk. In the early stages of retinol introduction, do not slug over retinol.

How to use it

Apply on fully cleansed skin as the absolute final step — after serums and moisturiser, not instead of them. A thin layer is sufficient. Thick application does not increase efficacy; petrolatum works at the surface, not below it. Apply at night; cleanse normally in the morning.

The Lux & Glo position

Slugging is compatible with the ritual and most useful as a short-term barrier recovery tool — on recovery nights, or when the skin is showing sensitivity, dryness, or visible disruption. The ritual's moisturiser provides occlusion through its squalane and shea component; slugging adds a second, more absolute occlusive layer for conditions that warrant it. It is not a nightly default for most skin types. It is a targeted repair intervention.