Humectants, Emollients & Occlusives: What's The Difference?

I liken the world of moisturizers to a spectrum—it's not an exact comparison, but it does help you visualize it: On one end you have options that pull water into the skin, and on the other, there are those that act as a seal. And at various points on this spectrum, you have humectants, emollients, and occlusives—words you might see pop up in beauty stories or on a visit to a dermatologist's office. Understanding them is actually incredibly important—they dictate how you should use and layer your products. It's one of those concepts that once you understand, the world of skin care just makes more sense. 

And the first thing you should know is that the below are categories of ingredients: each specifying a different set of qualities, board-certified dermatologist Keira Barr, M.D. tells me (who also medically reviewed this article). This is why you don't see a serum called a "Humectant Serum"; rather, it'll be identified as the specific ingredient itself, like "Hyaluronic Acid Serum." The other thing to note is these products are usually formulated with some combination of the three—unless you're putting a raw ingredient on your skin.

So let's dive into the specifics, shall we? 

An emollient is something that softens the skin and makes it feel more comfortable by filling in cracks. This is why emollients are often used for irritated, inflamed, or reactive skin2. Butters, certain oils, lipids, and fatty acids are all emollients. Emollients are also usually formulated with a humectant and occlusive, in order to perform its job better (as well as other ingredients entirely, like antioxidants; Barr notes that alone, they likely don't do enough for the skin). These products can range from light lotions, which contain more humectants, to thick creams, which likely contain more occlusives. 

The thickest end of the spectrum, these seal moisture into skin. In the natural world, these are your waxes like candelilla, carnauba, and palm kernel, beeswax, or lanolin ("traditional" examples include silicones and petroleum). They are also many types of oils, like jojoba or olive oils. Given they act as a water retention barrier, they also act as a barrier to outside forces: This is why they should be the last step of your routine. After you slick on an occlusive, anything layered on top isn't getting past it. 

Understanding the different types of moisturizers, and how they do their job of keeping skin hydrated, is essential. Once you know these key categories, you'll better understand the beauty world around you.