The premise of slugging—a name inspired by the viscous texture of snail mucous—is simple: By applying an occlusive agent as the last step of your nighttime beauty routine, you strengthen the skin’s barrier and trap in hydration. “It’s something we’ve always done in dermatology,” says Montreal-based dermatologist Loukia Mitsos. “When the skin is dry, it lacks intercellular lipids, which form a kind of glue to hold the skin cells together; without this support, the skin barrier is defective.
However, it’s important to not use certain active ingredients on slugging nights, warns Mitsos. “The absorption of all the care applied under the occlusive is amplified, so you should avoid active ingredients such as AHA and BHA acids and retinoids, which can dry out the skin even more and cause irritation.” Another downside: Although it does wonders for dry skin and eczema, the technique is not recommended for oily skin.