Slugging: When It Helps and When It Doesn't
Slugging — the practice of applying a layer of petroleum jelly or similar occlusive as the final step of your nighttime routine — went viral through skincare…
Slugging — the practice of applying a layer of petroleum jelly or similar occlusive as the final step of your nighttime routine — went viral through skincare communities and TikTok. Devotees swear by its transformative effects. Critics worry about breakouts and suffocated skin. The reality, as usual, lies somewhere in between.
What Slugging Actually Does
Slugging creates an occlusive barrier on the skin’s surface. This barrier:
Prevents transepidermal water loss (TEWL): Water naturally evaporates from your skin. An occlusive layer dramatically reduces this evaporation, keeping the skin’s natural moisture trapped inside.
Protects the barrier: The physical layer shields skin from environmental factors overnight.
Enhances product absorption: Products applied underneath an occlusive can’t evaporate and have more time to absorb. (This can be beneficial or problematic depending on what’s underneath.)
Supports barrier repair: Reduced TEWL allows damaged barriers to heal in a protected environment.
What slugging doesn’t do is “suffocate” skin in any meaningful sense. Skin doesn’t breathe in the respiratory sense — it receives oxygen from blood, not air.
The Science of Occlusion
Petroleum jelly (petrolatum) is the classic occlusive because it’s remarkably effective. Studies show it reduces TEWL by over 98% — more than almost any other ingredient.
This occlusive effect has been studied in wound healing, dermatological treatments, and barrier repair. Occlusion is a legitimate therapeutic approach, not just a social media trend.
Other occlusives work similarly but with varying effectiveness:
- Mineral oil and paraffin (moderately occlusive)
- Lanolin (occlusive plus emollient)
- Silicones like dimethicone (moderately occlusive)
- Plant oils and butters (mildly to moderately occlusive)
None match petroleum jelly’s occlusive power, which is why it’s the traditional slugging choice.
When Slugging Helps
Severely Dry or Dehydrated Skin
If your skin can’t retain moisture despite good moisturisers, occlusion forces the issue. Trapped water allows the stratum corneum to properly hydrate overnight.
Barrier Damage
Over-exfoliated, retinoid-damaged, or environmentally stressed skin benefits from occlusion. The protective layer lets the barrier repair without interference.
Harsh Climates
Cold, dry, or windy conditions increase TEWL significantly. Slugging provides extra protection when environmental conditions are extreme.
Supporting Healing
Post-procedure (after laser, peels, or microneedling — once recommended by your provider), occlusion can support recovery.
Stubborn Dry Patches
Localised areas that don’t respond to regular moisturising may benefit from targeted occlusion.
Retinoid Adjustment
During the retinisation period, when skin is peeling and dry, slugging (on non-retinoid nights) can help maintain hydration.
When Slugging Doesn’t Help — Or Harms
Acne-Prone and Oily Skin
This is where slugging becomes controversial. Petroleum jelly itself is non-comedogenic in testing — it’s too large molecularly to penetrate pores.
However:
- Occlusion over existing comedogenic products or accumulated sebum can trap pore-clogging substances
- The humid environment under an occlusive may encourage bacterial proliferation
- Some acne-prone individuals simply don’t tolerate heavy occlusion well
The theoretical safety doesn’t always match practical reality for breakout-prone skin.
Fungal Acne (Malassezia Folliculitis)
The warm, moist environment under an occlusive can encourage yeast growth. If you’re prone to fungal acne, slugging may trigger or worsen breakouts.
Over Active Ingredients
Slugging over retinoids, AHAs, or BHAs increases their penetration and can significantly increase irritation. This isn’t an enhanced benefit — it’s enhanced damage.
If you want to slug on retinoid nights, apply the retinoid first, wait for absorption, apply moisturiser, wait again, then slug. Even then, proceed cautiously.
Existing Irritation or Dermatitis
Occlusion over inflamed or irritated skin can worsen symptoms by trapping irritants or pathogens against the skin.
Skin That Doesn’t Need It
Not everyone benefits from occlusion. If your skin is balanced, your barrier is healthy, and your climate is moderate, slugging adds unnecessary steps without clear benefit.
How to Slug Properly
If you want to try slugging:
Cleanse thoroughly. Anything on your skin gets trapped under the occlusive. Make sure you’re sealing in clean skin.
Apply your routine as normal. Hydrating layers (hyaluronic acid, moisturiser) are ideal under occlusion.
Avoid actives directly under slug. No retinoids, AHAs, or BHAs immediately before slugging. These should be used on alternate nights or applied much earlier with time to absorb.
Apply a thin layer of occlusive. You don’t need thick globs — a thin film provides full occlusion. Petroleum jelly, Aquaphor, or similar products work.
Sleep on it. The occlusion works overnight.
Cleanse in the morning. Remove the occlusive layer with your regular cleanser.
The Skincare Sandwich Variation
Some people “sandwich” irritating products between moisturiser layers, with an occlusive on top. For example: moisturiser → retinoid → moisturiser → occlusive.
This can buffer irritation while still allowing the retinoid to work. It’s a middle-ground approach for those who want benefits of both occlusion and active ingredients.
Occlusive Options
Petroleum Jelly (Vaseline)
The most effective occlusive. Pure, minimal irritation risk, very inexpensive. The greasy texture is the only downside.
Aquaphor / Healing Ointments
Petroleum jelly with added emollients and healing ingredients like panthenol. Slightly more cosmetically elegant while retaining high occlusion.
Lanolin
Natural occlusive from sheep’s wool. Highly effective but can cause sensitivity in some people. Not suitable for vegans.
CeraVe Healing Ointment
Contains ceramides and hyaluronic acid alongside petrolatum. May provide additional barrier support.
Silicone-Based Products
Less occlusive than petroleum jelly but more cosmetically elegant. Suitable for those who dislike greasiness.
Plant Butters and Oils
Shea butter, cocoa butter, and heavy oils provide mild to moderate occlusion. Less effective but more appealing to those avoiding petroleum products.
Who Should Try It
Slugging is worth trying if:
- You have dry, dehydrated, or barrier-damaged skin
- Regular moisturising isn’t maintaining hydration
- You’re adjusting to retinoids and experiencing dryness
- You live in or are visiting harsh climates
- You don’t break out easily
Who Should Avoid It
Skip slugging if:
- You’re acne-prone and have experienced breakouts from heavy products
- You have fungal acne or are prone to yeast-related breakouts
- Your skin is currently irritated or inflamed
- You want to apply active ingredients simultaneously
- Your skin is already well-balanced with no hydration issues
The Verdict
Slugging is a legitimate occlusive technique with real benefits for the right skin types and situations. It’s not a miracle cure for all skin problems, and it’s not suitable for everyone.
The practice works because occlusion is scientifically sound — reducing water loss helps maintain hydration and supports barrier function. The social media hype has simply given a name to something dermatologists have recommended for decades.
Try it if your skin suggests you’d benefit. Skip it if you have reasons to expect problems. Like most skincare practices, individual variation determines whether it helps or harms.
There’s no one-size-fits-all answer — just your skin, its current condition, and whether trapping moisture in overnight serves your specific needs.