Difference Between Humectant, Emollient, Occlusive - The Dermatology Review

Difference Between Humectant, Emollient, Occlusive

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08.26.19 AD DISCLOSURE

In the past, you’ve probably picked out moisturizers based on a specific brand name or the marketing claims made by brands. But have you ever considered the different types of moisturizers? Based on the ingredients they include, moisturizers can be broken down into three main categories: humectant, emollient, and occlusive. We know what you’re probably thinking, “That’s good to know, but what’s the difference? And which one should I choose for my skin type?”. In this post, we’ll answer these questions and more so you’ll know the difference between humectant, emollient, and occlusive moisturizers.

Understanding the skin barrier

In order to discuss the different types of moisturizers, we’ll need a brief discussion on the structure and function of the skin barrier. The stratum corneum, the outermost layer of the epidermis (top layer of skin), is the primary barrier of the skin and is very important in maintaining water balance. It consists of corneocytes (dead skin cells) held together by a lipid matrix composed of ceramides, cholesterol, and fatty acids. You can think of this barrier as having a “brick and mortar” structure — the corneocytes are the bricks and the lipids are the mortar.

The Natural Moisturizing Factor (NMF) is another component of the stratum corneum. The NMF is primarily composed of free amino acids and various derivatives of these amino acids, for example, PCA, urocanic acid, and inorganic salts, sugars, as well as urea and lactic acid. The role of the NMF is to maintain adequate skin hydration. The NMF can become depleted with age and also from routine exposure to sensitizing ingredients like drying cleansing agents and denatured alcohol. This leads to visibly dry, tight-feeling, flaky skin.

Humectant definition

A humectant is a hygroscopic substance that has a molecular structure with several hydrophilic (water loving) groups, such as hydroxyl groups (OH) and/or amine groups (NH2). There needs to be enough NH2 and OH groups on the molecule to counteract the nonpolar parts (i.e. hydrocarbon portion), allowing the overall molecule to be polar enough to attract water. The OH and NH2 groups hydrogen bond with water, essentially “grabbing” it and holding it on the skin. Humectants pull water from the dermis to the epidermis and stratum corneum. In addition, humectants can draw water vapor from the air to help moisturize the skin if the humidity is over 50 percent.

A few examples of skin care ingredients that can be classified as humectants include the following:

  • Hyaluronic acid
  • Urea
  • Alpha-hydroxy acids (AHAs)
  • Amino acids
  • Peptides
  • Sugar alcohols (glycerin, sorbitol, xylitol, etc.)
  • Aloe vera
  • Honey

Humectant products can be used by all skin types, but they are best for those with normal to slightly dry skin. Since humectants slow water from evaporating in the epidermis, they help to keep the skin hydrated. Humectants also promote the shedding of dead cells (called desquamation) by breaking down the proteins that hold the cells together. However, one drawback with humectant products is that they can sometimes pull too much moisture from the lower layers of skin when the air in your surrounding environment is very dry.

Humectants provide temporary anti-aging effects because the extra hydration is extra volume, which effectively plumps out the skin and makes lines and wrinkles less noticeable. However, this effect is transient – as soon as the moisture content in skin decreases, lines and wrinkles will return to normal size. Unfortunately, some skin care brands may use high concentrations of humectants in their products that are claimed to provide anti-aging effects without any other ingredients to correct signs of aging. You may think the product is working because your skin looks plump after use, but these effects are just from the humectant.

Emollient definition

An emollient is an oily substance that fills in the spaces between dead skin cells, thus creating a smooth skin surface. Basically, an emollient is a film forming substance that makes the skin feel and look smooth. While an emollient will provide some occlusive effects, the primary function is to help soften the skin.

Examples of emollients include the following:

  • Butters
  • Oils
  • Esters
  • Lipids
  • Fatty acids
  • Ceramides

Emollient ingredients help to repair the skin barrier function. Remember from above that the skin barrier is composed of dead skin cells held together by a lipid matrix. Without these essential lipids, the barrier is weakened. A weak or damaged barrier leads to transepidermal water loss (TEWL) and may allow harmful things like allergens, bacteria, and irritants to pass through into the deeper layers of skin. This can lead to symptoms of dryness, itching, and irritation, and may eventually cause skin conditions such as acne, eczema, sensitive skin, and even signs of aging. Using emollients can help to fill in the spaces between dead skin cells where the barrier has been depleted, ultimately leading to soft hydrated skin.

Nearly everyone can benefit from an emollient product. Whether or not you should use an emollient moisturizer largely depends on what emollient ingredient is used in the product. For example, those with oily or acne prone skin should avoid products with comedogenic emollients, such as coconut oil and avocado oil, and only use products with non-comedogenic emollients, such as jojoba oil, safflower oil, and squalane, to prevent clogged pores and acne breakouts.

Occlusive definition

Occlusive moisturizers contain ingredients that create a physical barrier on top of the skin that helps prevent trans-epidermal water. These ingredients feel thick and heavy after application since they are not absorbed into the skin.

Examples of occlusive ingredients include the following:

  • Petrolatum
  • Mineral oil
  • Lanolin
  • Waxes
  • Silicones

Since occlusive ingredients form a protective barrier on the surface of skin, they are best for those with very dry skin and conditions like eczema and psoriasis. Applying an occlusive moisturizer immediately after bathing may be an effective way to trap additional water in the skin.

Those with oily or acne-prone skin should avoid most occlusives except silicones. It’s a common misconception that silicones can cause or worsen acne. Silicones have wide spaces between each molecule, which form a molecular lattice. Upon application to the skin, this lattice enables silicones to form a film on the surface while still allowing skin to “breathe”. Oxygen, nitrogen, and other nutrients can still pass through the film formed by silicones. However, most silicones do not allow water to pass through, which is an ideal quality for preventing transepidermal water loss (TEWL) – a leading cause of dehydrated skin. In addition, the large molecular size and volatility of silicones also dispels the claim that these ingredients can clog pores and cause acne. Since silicones evaporate quickly and do not penetrate the pore lining, they cannot cause acne.

Which is best: humectant, emollient, or occlusive?

Now that you know the difference between humectant, emollient, and occlusive moisturizers, you can probably see that there are advantages and disadvantages with each type. Thus, one type is not necessarily better than the other. A great approach is to look for products that combine all three of these in one formula. The humectant will draw in moisture while the occlusive will lock in that moisture in, and the emollient will keep the skin soft and smooth. Below are the products we recommend that effectively combine these three ingredient types in their formulas.

Formulyst Age Defying Daily Moisturizer
This hydrating anti-aging formula contains humectants like glycerin, gluconolactone, sodium lactate, and Aloe vera leaf juice to draw moisture into the skin. It also contains several emollients, like squalane and caprylic/capric triglyceride from coconut, as well as a couple occlusives like dimethicone to lock in moisture. In addition to these moisturizing ingredients, this formula is rich in antioxidants and a blend of natural complexes – including rosemary extract, sunflower extract,and nourishing watermelon rind. Overall, Formulyst Age Defying Daily Moisturizer helps to keep skin feeling smooth, hydrated, and looking its most radiant.

Formulyst Anti-Aging Night Cream with Retinol
Specifically formulated to target the visible signs of aging, Formulyst’s Anti-Aging Night Cream deeply moisturizes skin with humectants, emollients, and occlusives. The humectant sodium hyaluronate is combined with occlusives like cyclopentasiloxane and dimethicone to ensure that moisture is absorbed and locked in. This formula also helps the skin feel silky smooth thanks to safflower seed oil, jojoba oil, and squalane (all non-comedogenic emollients). In addition to these moisturizing ingredients, this formula uses Encapsulated Retinol Technology to deliver a higher concentration of retinol to your skin overnight.

Formulyst Super Hyaluronic Water Moisturizer
Formulyst knows that hyaluronic acid is the key to healthy, hydrated skin, which is why the Super Hyaluronic Water Moisturizer was created. This formula contains sodium hyaluronate, the salt form of hyaluronic acid, which is an exceptional ingredient for adding hydration to the skin. As a humectant, sodium hyaluronate draws in moisture from the environment and can hold up to 1,000 times its weight in water. Formulyst Super Hyaluronic Water Moisturizer is also enriched with jojoba oil, apricot kernel oil, and squalane to promote soft, smooth skin.

References: Harwood A “Moisturizers” Jan 2019, VeryWellHealth.com “Humectants in Moisturizers”, LabMuffin.com “Skincare Chemistry: How to Pick Out Humectants” Jan 2019, DermatologyTimes.com “What is an emollient” Jan 2015, library.essentialwholesale.com “Occlusive, Emollient & Humectant – Terms To Know” June 2017, PaulasChoice.com “Silicone in Skincare”

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