This question comes from Instagram and other social media posts where there’s a ton of confusion around this topic.
What is “slugging”? It’s the practice of putting occlusive agents like or similar to vaseline/petrolatum over all sorts of other skin care products. The purpose is to intensify the product but does it really work?
4 Reasons to Think Twice Before You “Slug.”
- Slugging dilutes your skin care products. Putting an occlusive agent on your skin, does nothing by itself except reduce water evaporation through the skin. This is called transepidermal water loss, but who wants to say that all the time, so it’s abbreviated TEWL. 🙂 If you put an occlusive agent over an active, it may penetrate better due to more water retention in the barrier layer (epidermis). You can’t make the product itself stronger. There’s no science that I’ve seen on using vaseline or Aquaphor over highly engineered, usually expensive, already effective skincare products. Why potentially ruin a great skincare product?
- Slugging changes your products formulation by changing the pH. I don’t recommend using occlusive moisturizers over these already effective products because you can alter them and lose their effectiveness. For example, if you try to intensify a retinoid this way, you may get more irritation, clogged pores, and you may get less penetration depending on how the product was formulated. But bottom line….anything acidic is not a good idea. So for sure not vitamin C, retinol (retinoid acid) or any of the alpha or beta hydroxy acids like glycolic acid, salicylic acid, etc.
- Slugging may cause irritation. For example, what if you have, and many people do, a low level of irritation or allergy to propylene glycol (in many skincare products). If you occlude acids, it may cause irritation. But it’s more likely it would inactivate the actives in the product. Many of these products need a certain pH initially to penetrate well. Do you want to change that?
- Slugging clogs pores and may cause acne. In some who are very dry, it’s almost impossible to cause clogged pores. Others, with plenty of oil of their own, many products can clog pores and often unwanted acne is the result. Some “natural oils” can do this also. This type of acne will typically show up 4-8 weeks after you start the product. Occlusives basically don’t allow TEWL or sweat evaporation. Natural oils like jojoba and apricot, for example, don’t tend to be as occlusive as petrolatum, waxes, mineral oils, and solid nut “butters.” These ingredients though as part of a balanced formulation may be great.
Hope this helps,
Brandith Irwin, MD