The idea of slathering your face with petroleum jelly before bed might sound like a recipe for disaster, especially if you’ve spent years avoiding anything remotely greasy. Yet this practice known as “slugging” has exploded in popularity, with skincare enthusiasts claiming transformative results for dry, dehydrated skin. But is there legitimate science behind this trend, or is it just another fleeting social media fad?
Petroleum jelly has actually been around since 1859, when Robert Chesebrough discovered a residue that oil workers used to heal cuts and burns. What’s old is new again, as this simple product has become the cornerstone of a skincare technique that promises to seal in moisture and leave skin remarkably hydrated by morning.
Slugging works through a simple but powerful mechanism: occlusion. By creating a physical barrier on the skin’s surface, petroleum jelly prevents transepidermal water loss (TEWL) the natural evaporation of moisture from your skin into the surrounding environment. This water loss accelerates dramatically in dry environments and can leave skin parched and compromised. A thin layer of petroleum jelly reduces TEWL by up to 98%, according to research published in the Journal of Dermatological Science.
Dr. Shereene Idriss, a board-certified dermatologist in New York City, explains: “Petroleum jelly doesn’t actually add moisture to the skin it locks in whatever hydration is already there.” This distinction matters because slugging works best when applied over humectant-rich products that first draw water into the skin.
The Science of Skin Barrier Function
Our skin’s outermost layer the stratum corneum functions as a brick-and-mortar system. The “bricks” are dead skin cells called corneocytes, while the “mortar” consists of lipids (ceramides, cholesterol, and fatty acids) that hold everything together. This structure prevents excessive water loss while keeping irritants and pathogens out.
Many factors can damage this barrier: harsh cleansers, environmental pollutants, low humidity, aging, and certain skin conditions like eczema or rosacea. When the barrier becomes compromised, moisture escapes more easily, and skin becomes dry, irritated, and more susceptible to inflammation.
A 2016 study in the International Journal of Cosmetic Science demonstrated that occlusive agents like petroleum jelly don’t just prevent water loss they actually help repair a damaged skin barrier by giving it time to heal itself. By reducing TEWL, slugging creates an environment where your skin can restore its natural lipid production and repair damaged cells.
But what makes petroleum jelly so effective compared to other occlusives? Its molecular structure consists of hydrocarbon chains that form a semi-solid matrix too large to penetrate deeply into skin. This creates a protective film that sits on the surface rather than absorbing in. Unlike many ingredients that claim to be “non-comedogenic,” petroleum jelly has extensive research backing its safety it’s one of the few substances with a comedogenicity rating of zero, meaning it won’t clog pores for most people.
Dr. Ranella Hirsch, a dermatologist with over 20 years of experience, notes: “Petroleum jelly has been studied more extensively than almost any other topical skin product. The data consistently shows it’s both effective and safe for most skin types.”
The Practical Application and Benefits
The beauty of slugging lies in its simplicity. After completing your regular nighttime skincare routine cleansing, treatments, and moisturizer you apply a thin layer of petroleum jelly as the final step. The key word here is “thin” you need just enough to create a light sheen, not a thick mask that transfers to your pillowcase.
I tried slugging during a particularly brutal winter when my skin felt like sandpaper despite using expensive moisturizers. The first morning after slugging, I was genuinely surprised my skin felt noticeably softer and looked less red and irritated. After a week of consistent use, the flaky patches around my nose had completely disappeared.
This anecdotal experience aligns with the scientific benefits:
- Enhanced hydration: By preventing water loss overnight (when skin naturally loses more moisture), slugging helps maintain optimal hydration levels.
- Barrier repair: For compromised skin barriers, slugging creates a protective environment that supports natural healing processes.
- Reduced irritation: The occlusive layer can prevent irritants from contacting the skin, making it particularly beneficial for sensitive skin types.
- Improved product efficacy: When applied over treatment products, petroleum jelly may enhance their penetration and effectiveness by trapping them against the skin.
- Wound healing: Research in the Journal of Surgical Research found petroleum jelly can speed wound healing by keeping the area moist and protected.
A 2022 review in the Journal of the American Academy of Dermatology confirmed that petroleum jelly’s occlusive properties make it particularly effective for treating extremely dry skin conditions, noting its long history of safety and efficacy.
Not everyone will benefit equally from slugging, though. Dr. Joshua Zeichner, Director of Cosmetic and Clinical Research at Mount Sinai Hospital, cautions: “If you have oily or acne-prone skin, applying an occlusive like petroleum jelly all over your face may not be the best idea. Consider spot-treating dry areas instead.”
This makes sense physiologically. While petroleum jelly itself won’t cause acne, trapping excess sebum, dead skin cells, and bacteria under an occlusive layer could potentially exacerbate breakouts in already acne-prone individuals.
Another consideration is what products you apply underneath. Slugging amplifies everything beneath it beneficial ingredients and potentially irritating ones alike. Avoid slugging over retinoids, exfoliating acids (like glycolic or salicylic), or other potentially irritating actives until you know how your skin reacts.
My friend Lisa learned this the hard way when she slugged over a new retinol serum and woke up with an irritated, red face. “It was like I created a retinol pressure cooker on my face,” she told me, laughing about it months later.
For best results, pair slugging with hydrating ingredients like hyaluronic acid, glycerin, or niacinamide. These humectants draw moisture into the skin, which the petroleum jelly then seals in place.
Beyond facial application, slugging works wonders for chronically dry areas like elbows, knees, and feet. I’ve found that applying petroleum jelly to slightly damp feet and covering them with cotton socks before bed transforms even the roughest heels by morning.
The environmental impact of petroleum-based products concerns some users. Petroleum jelly is a byproduct of oil refining, raising sustainability questions. For those seeking alternatives, plant-based options like shea butter, cocoa butter, or products containing natural waxes can provide similar occlusive benefits, though typically with less intensive barrier properties than petroleum jelly.
Research from the British Journal of Dermatology suggests that natural plant oils and butters can reduce TEWL by 20-30% not as dramatic as petroleum jelly’s 98%, but still beneficial for mild to moderate dryness.
Timing matters too. Slugging delivers maximum benefits during sleep, when skin naturally focuses on repair. During this time, blood flow to skin increases, and the skin’s permeability rises, making it more receptive to both water loss and treatment absorption. An occlusive layer during this critical period helps optimize the skin’s natural recovery processes.
The most compelling evidence for slugging comes from its results. While social media might exaggerate the benefits, dermatologists have long recommended petroleum jelly for compromised skin barriers. Dr. Whitney Bowe, a dermatologist and research scientist, points out: “We’ve been recommending petroleum jelly in dermatology for decades. What’s new is applying it as part of a layered routine rather than directly on dry skin.”
Ultimately, slugging represents something rare in the beauty world an inexpensive, simple technique with genuine scientific backing. For those with dry, dehydrated skin seeking overnight transformation, the humble petroleum jelly deserves consideration. The magic isn’t in discovering something new, but in rediscovering something that worked all along.
Just remember like any skincare technique, slugging isn’t one-size-fits-all. Pay attention to your skin’s response and adjust accordingly. That might mean slugging only occasionally, targeting specific dry areas, or skipping it entirely if your skin tends toward oiliness or acne. The science supports its effectiveness, but your skin’s individual needs should always guide your routine.
