Occlusives vs. Emollients vs. Humectants: What Does a Damaged Skin Barrier Need?

A moisturizer doesn't have to add water to help your skin stay hydrated. When the skin barrier is damaged, water escapes more easily, and a moisturizer can help in three ways. Occlusives slow water loss, emollients soften rough skin, and humectants attract and hold water. One moisturizer can combine all three.^{1, 2} So when you're choosing products, look at which of the three jobs they already cover.

What changes when the skin barrier is damaged?

Your skin's outer layer is made of flattened cells layered a little like roof shingles, with lipids packed between them. Ceramides, cholesterol and free fatty acids are the main types, and the layers they form help keep water in and limit what gets through from outside. When their arrangement is disturbed, water can escape more easily.²

Water reaches the outer skin from deeper layers. Skin's own water-binding substances help hold it there, while the lipids between the cells slow its escape, and a moisturizer can support both jobs, holding water and keeping it from leaving too quickly.^{1, 10}

What do occlusives do?

Occlusives slow the loss of water from skin by forming a water-resistant layer that reduces evaporation, a bit like a lid on a pot. Mineral oil, lanolin and some silicones are occlusives, though the effect varies with the ingredient and the formula.¹ That's why a product made without any water can still help skin stay hydrated, by slowing the loss of water that's already there.

What do emollients do?

Emollients make skin feel softer and smoother. They spread over the surface and fill the spaces between dry flakes, helping rough skin feel more even, and oils and other lipid ingredients often act as emollients.¹ Squalane and jojoba oil soften skin and also help it retain moisture.^{8, 11}

What do humectants do?

Humectants attract and hold water in skin's outer layer. Glycerin, urea and hyaluronic acid are common examples. The water can come from deeper in the skin, and in humid air, some can also come from the surroundings.¹

Humectants are often paired with occlusives, because holding water and slowing its escape work well together. Glycerin also helps skin stay flexible and supports barrier function, so the roles overlap.⁹

The three roles side by side

One moisturizer can combine all three roles, and individual ingredients may do more than one job.¹

How do barrier lipids fit in?

Some moisturizers also supply ceramides, cholesterol and free fatty acids, the lipids found between your skin's outer cells, and research on lipid mixtures helps explain why the combination matters.^{2, 4}

In one study, researchers disrupted the barrier of mouse skin with acetone and then applied lipid mixtures. A mixture containing all three lipid types allowed normal barrier recovery, while several single lipids and two-part mixtures delayed it. Related mouse research found that applied barrier lipids could reach living skin cells and enter the structures that carry new lipids to the outer layer.^{3, 4} In those mice, having all three mattered.

Researchers have also studied barrier-lipid mixtures in people. In one study, children with eczema kept up their usual treatment while switching to a ceramide-rich moisturizer containing several barrier lipids, and the switch was linked to less water loss and better-organized barrier lipids.⁵

What about squalane and jojoba?

Skin also makes sebum, the oil that reaches its surface through pores, and sebum contains squalene and wax esters. Its makeup differs from the ceramides, cholesterol and free fatty acids packed between skin cells.⁶ Squalane is a more stable form of squalene that resists changes caused by oxygen, and jojoba oil is rich in wax esters, a type of lipid also found in sebum. Their moisturizing role comes from softening skin and helping it retain water.^{7, 8, 11}

What should you look for in a moisturizer?

A water-based cream might contain glycerin to bind water, squalane to soften skin and mineral oil to slow evaporation, which would put all three roles into one moisturizing step.^{1, 11}

When choosing a moisturizer:

1. Check what your moisturizer already combines. Look for humectants such as glycerin alongside ingredients that soften skin and slow water loss. A cream may already provide the combination you're looking for.
2. Consider where a waterless product would fit. It can add emollient lipids and help retain moisture supplied by damp skin or a water-based step you already use.¹

The guide to anhydrous and water-based serums explains the formats in more detail.

How we built Omnia

We designed Omnia to help skin hold on to its own moisture. It's a waterless solid serum with a softening base of squalane, jojoba esters, plant-derived esters and oat kernel oil, selected to help skin feel smooth and retain moisture. We've paired Ceramide NP, a type of barrier lipid, with a phytosterol amino acid complex, a lipid made from plant sterols and an amino acid, to support moisture retention with the barrier's structure in mind.

After washing, pat skin lightly so it still feels damp, then apply Omnia to help keep the water from escaping. If your skin feels comfortable and well moisturized this way, there's no need to add another moisturizing product.¹

If your skin still feels dry, check which of the three jobs your routine is missing.

Sources

1. Sethi A, et al. Moisturizers: the slippery road. Indian Journal of Dermatology, 2016.
2. van Smeden J, et al. The important role of stratum corneum lipids for the cutaneous barrier function. Biochimica et Biophysica Acta, 2014.
3. Mao-Qiang M, et al. Exogenous nonphysiologic vs physiologic lipids: divergent mechanisms for correction of permeability barrier dysfunction. Archives of Dermatology, 1995.
4. Man MQ, et al. Exogenous lipids influence permeability barrier recovery in acetone-treated murine skin. Archives of Dermatology, 1993.
5. Chamlin SL, et al. Ceramide-dominant barrier repair lipids alleviate childhood atopic dermatitis: changes in barrier function provide a sensitive indicator of disease activity. Journal of the American Academy of Dermatology, 2002.
6. Picardo M, et al. Sebaceous gland lipids. Dermato-Endocrinology, 2009.
7. Brunner G, et al. Phase equilibrium of hydrogen, carbon dioxide, squalene, and squalane. Journal of Chemical & Engineering Data, 2009.
8. Gad HA, et al. Jojoba oil: an updated comprehensive review on chemistry, pharmaceutical uses, and toxicity. Polymers, 2021.
9. Fluhr JW, et al. Glycerol and the skin: holistic approach to its origin and functions. British Journal of Dermatology, 2008.
10. Verdier-Sévrain S, Bonté F. Skin hydration: a review on its molecular mechanisms. Journal of Cosmetic Dermatology, 2007.
11. Tanii T, et al. Clinical Evaluations of Squalane in Patients with Xerotic Dermatoses and the Results of Patch Test of Squalane and its Moisturizing Effects. Skin Research, 1991.