Vaseline is a moisturizer, but not in the way most people think of one. It doesn’t add moisture to your skin. Instead, it forms a physical barrier that prevents the moisture already in your skin from escaping. Among oil-based moisturizers, petrolatum (the active ingredient in Vaseline) is the most effective at this job, reducing water loss through the skin by roughly 98%. Other common oil-based ingredients only manage 20% to 30%.
How Vaseline Works Differently Than Lotion
Moisturizers generally fall into three categories: humectants, emollients, and occlusives. Humectants (like glycerin or hyaluronic acid) pull water into your skin. Emollients (like shea butter or squalane) soften skin by filling gaps between skin cells and improving the skin barrier from within. Occlusives sit on top of the skin and physically block water from evaporating.
Vaseline is one of the purest examples of an occlusive. It creates a greasy, protective layer over the skin’s surface rather than penetrating or influencing how skin cells function. This is why it feels heavier and stickier than a typical lotion. Most lotions combine all three types of ingredients to both deliver and lock in hydration. Vaseline only does the locking-in part.
That distinction matters in practice. If your skin is already well-hydrated, Vaseline keeps it that way extremely effectively. If your skin is dehydrated, Vaseline alone won’t fix the problem because there’s less moisture underneath to trap. That’s why dermatologists recommend applying it to damp skin, right after washing or bathing, when there’s still water on the surface for the barrier to seal in.
Skin Barrier Repair
Your skin’s outermost layer naturally waterproofs itself using a mix of fats (cholesterol, fatty acids, and ceramides) arranged in thin sheets between skin cells. When that barrier gets disrupted by harsh soaps, dry air, or skin conditions like eczema, water escapes faster and skin becomes dry, cracked, and irritated.
Petrolatum steps in as a temporary replacement for that damaged barrier. A study comparing pure petrolatum against a cream containing fats designed to mimic the skin’s own lipids found that petrolatum performed just as well at restoring the barrier over a 14-day recovery period. In other words, you don’t necessarily need a fancy formulation to help damaged skin heal. Plain petroleum jelly does the job.
Will It Clog Your Pores?
Despite its thick, greasy texture, medical-grade white petrolatum (the kind in Vaseline) is non-comedogenic, meaning it doesn’t clog pores. It’s also hypoallergenic. The molecules in refined petrolatum are too large to penetrate into pores, so the barrier sits on the skin’s surface rather than settling into follicles. This makes it safe for sensitive and acne-prone skin, though the heavy feel isn’t for everyone.
One thing to watch for: some petroleum jelly products include lanolin, a common allergen that can cause skin irritation. If you’ve had reactions to wool or lanolin-containing products before, check the ingredient list and stick with plain petrolatum.
Slugging: The Overnight Technique
Slugging is the practice of applying a thin layer of Vaseline over your entire face as the last step in a nighttime skincare routine. The goal is intense overnight hydration. The occlusive layer also helps serums and other active ingredients stay in contact with your skin longer instead of evaporating or rubbing off on your pillow.
A few practical notes if you want to try it. Avoid the skin directly around your eyelids. Petroleum jelly in that area can cause milia, tiny white bumps that look like small pimples. If your skin runs oily, the heavy layer may feel uncomfortable and unnecessary, since your natural oils already provide some occlusion. Hot, humid climates also make slugging feel oppressive, and the extra barrier can trap sweat against the skin.
Getting the Most Out of It
The single most important rule with Vaseline is to apply it to damp skin. This is the recommendation from the American Academy of Dermatology for both skin and nails. After a shower, pat your skin so it’s still slightly wet and then apply a thin layer of Vaseline. This traps that surface water underneath the barrier, giving your skin more moisture to work with.
If you’re using Vaseline on very dry or cracked areas like heels, elbows, or knuckles, layering it over a humectant-based lotion gives you the best of both worlds. The lotion delivers hydration, and the Vaseline locks it in. For general daily use on the body, this combination outperforms either product alone.
On its own, Vaseline works best for people with dry, sensitive, or eczema-prone skin who need strong barrier protection without fragrances, preservatives, or other potential irritants. It’s one of the simplest, cheapest, and most effective options available, as long as you understand that its job is keeping moisture in rather than putting moisture in.