Humectants, emollients, and occlusives: what’s the difference

Key Takeaways

• Humectants draw water toward the skin’s outer layer, emollients fill in gaps so skin can feel softer, and occlusives form a coating that helps slow water loss.

• Most moisturizers combine all three, and many ingredients do more than one job.

• A 2022 review notes that humectants are usually paired with an occlusive, because water loss can increase when a humectant is applied alone.

How a moisturizer is put together

Most moisturizers are built from three kinds of ingredient. DermNet, the dermatology reference site, lists the components of moisturizers as emollients, occlusives, and humectants. A 2022 review of moisturizers in Medicina adds that “many moisturizer ingredients serve more than one function.”

Humectants: ingredients that pull in water

The Medicina review describes a humectant as a substance that draws moisture toward the stratum corneum, both from the air and from the layers below. When the air is drier than 80% relative humidity, it says humectants mainly draw on the water underneath.

DermNet lists Glycerin, Urea, and Alpha Hydroxy Acids (AHAs) such as Lactic Acid as humectants, and the Medicina review includes Hyaluronic Acid. Because water loss through the skin can increase when a humectant is used on its own, the review notes that humectants are usually used with an occlusive. That pairing is also why how to use Hyaluronic Acid comes down to what you layer over it.

Emollients: ingredients that soften

According to the Medicina review, an emollient “fills the gaps in the stratum corneum and gives a soft feeling.” DermNet gives Lanolin and Glyceryl Stearate as examples and says emollients work by filling cracks in the skin’s outermost layer, so skin can feel softer and look visibly smoother. Not every emollient does much to hold water in, though. The review notes that some have little moisturizing function.

Occlusives: ingredients that seal

DermNet describes occlusives as oily ingredients that form a water-repelling layer on skin to reduce evaporative water loss. Its examples are Petrolatum, Paraffin, Mineral Oil, and Dimethicone. The Medicina review calls Petrolatum and Mineral Oil the occlusives “with the best sealing performance,” though Petrolatum can feel sticky and look shiny.

Texture follows the same logic. DermNet ranks ointments as the most occlusive, then creams, then lotions. The review adds that occlusives work best applied right after washing or bathing. For where moisturizer sits among the other steps, see a standard skincare routine order.

Frequently Asked Questions

Are plant oils humectants, emollients, or occlusives?

They’re usually grouped with occlusives. The Medicina review lists vegetable oils among its occlusive ingredients, but it also reports that Petrolatum is far more effective than olive oil at limiting water loss, so plant oils sit at the lighter end of the group.

Which type suits skin that feels very dry?

DermNet says skin that feels very dry may benefit from a greasy, occlusive moisturizer applied every couple of hours, while skin that feels only a little dry may need just a light moisturizer at night.