Finding a moisturizer is one of the most important steps toward building a successful skincare routine. Moisturizer is like an agent between the skin treatments and results. In this post, we will talk about three types of moisturizers – Emollients, Humectants, and Occlusives.
In addition, we will talk about layering moisturizer in our skincare routine.
What is a moisturizer?
There is no official definition of a moisturizer. The term “Moisturizer” was developed by marketers, promoting its function to moisten the skin. [1] Moisturizers can smoothen and hydrate the skin. People with all skin types can benefit from the proper use of moisturizers. [2] The role of moisturizer is not just moistening the skin, but several other benefits as well.
Why do we need one?
One of my recent posts was detailed on the skin barrier function, but let me give you a short version.
The epidermis is made up of several layers, with the basal layer – the first layer at the bottom and the stratum corneum – the dead layer on the top of the skin.
The skin barrier has distinct functions, the one we talk about most often is the skin permeability barrier function.
The major part of this permeability barrier function is stratum corneum, which is often described as a “Brick and Mortar” model, where the bricks are the corneocytes and the mortar are the intercellular lipids, consisting of ceramides, cholesterol, fatty acids, and sterols. [1]
Adequate hydration is needed for the skin’s natural process of exfoliation or desquamation. Corneodesmosomes (connections between the skin cells) are degraded by water-loving enzymes, which work less efficiently when our skin is not hydrated.
So, if your skin is dry, the dead cells (corneocytes) accumulate on the skin surface and won’t shed properly, leading to scaly flaky skin. [3]
Benefits
The different ways moisturizers can help are:
- Improve skin barrier repair [4]
- Provides a soothing protective film and protects the skin from friction
- Promotes the skin’s natural exfoliation process (desquamation) [5]
- Improves skin hydration by increasing stratum corneum water content
- Reduce trans-epidermal water loss
- Soothing effect on inflamed skin
- Downregulate the cytokines, thus reducing the itching [6]
Types
Moisturizers are of three different types and each functions in a very different way.
1. Emollients
They are mainly lipids and oils, which act as lubricating agents. They form a film on the skin surface and fill in any gaps resulting in soft and smooth skin. [6]
Depending on how much you apply, these can function as an occlusive as well. These can also replace some of the lost lipids in the skin barrier. Ceramides, cholesterol, and free fatty acids when applied at an optimal molar ratio of 1:1:1 to 3:1:1, can help repair the skin barrier.
Emollient moisturizers classification: [1] [6] [7]
- Dry emollients: Isopropyl palmitate, isostearyl alcohol, decyl oleate
- Fatty emollients: Propylene glycol, octyl stearate, glyceryl stearate, jojoba oil, castor oil
- Astringent emollients: Dimethicone, Cyclomethicone, octyl octanoate, isopropyl myristate
- Protective emollients: Isopropyl isostearate, diisopropyl dilinoleate
2. Humectants
They are hygroscopic compounds which means they attract water from two sources, from the dermis into the epidermis and in humid conditions from the environment to the epidermis. Many humectants have emollient properties as well.
Natural moisturizing factors (NMFs) are present inside the skin cells. They are made of a mixture of low molecular weight, soluble hygroscopic substances such as lactic acid, pyrrolidone carboxylic acid, and amino acids. These play a big role in hydrating the stratum corneum/topmost layer of skin.
You will often find these natural moisturizing factors in moisturizers for hydrating the skin.
- Glycerol is the most effective humectant. [6] [8]
- Urea is a humectant at a lower concentration (10%) but in higher concentrations (20–30%), it disrupts the hydrogen bonds of epidermal proteins leading to keratolysis and shedding of cells.
- Lactic acid is a humectant at lower concentrations and stimulates ceramide synthesis, particularly the L-isomer, leading to higher stratum corneum ceramide levels which enhances the skin barrier. [9]
However, humectants can also increase trans-epidermal water loss by increasing water absorption from the dermis into the epidermis, where it easily evaporates. Therefore, combination with an occlusive can enhance skin barrier function and hydration. [9]
A few examples of humectant moisturizers are honey, sorbitol, glycerin, panthenol, urea, gelatin, hyaluronic acid, alpha hydroxy acids (glycolic acid, lactic acid, sodium pyrrolidine, carboxylic acid), propylene glycol and butylene glycol. [6] [7]
3. Occlusives
They are substances that form a protective barrier on the skin surface and prevent transepidermal water loss (TEWL). They give the best results when applied to slightly damp skin. [9]
Petrolatum is the most effective classic occlusive moisturizer; a minimum concentration of 5%, can reduce trans-epidermal water loss by more than 98%. [10] That is amazing!!
This is the reason; slugging is a trend these days to repair the skin barrier. Lanolin, mineral oil, and silicones (e.g., dimethicone) can reduce trans-epidermal water loss by 20% to 30%.
However, occlusives can be less acceptable cosmetically due to their greasy consistency. [7]
Occlusive moisturizer examples:
- Hydrocarbons: Petroleum jelly, paraffin, mineral oil, squalene, caprylic/capric triglyceride
- Fatty acids: Stearic acid, lanolin acid
- Fatty alcohols: Lanolin, cetyl alcohol, stearyl alcohol
- Phospholipids: Lecithin
- Sterols: Cholesterol
- Vegetable waxes: Candelilla, carnauba
- Wax esters: Beeswax, stearyl stearate [7]
Different formulations
Moisturizers usually have a combination of humectants, emollients, and occlusives. One or the other form is predominant which affects the texture and consistency of a moisturizer.
The predominant form of delivery is an emulsion. The majority are lotions or creams. Ointments are thicker in consistency than creams. [9] [11]
How to apply
The right method for moisturizer application holds the key to maximum benefits. The best way is to apply moisturizer gently on slightly damp skin. [1] [4]
After 8 hours, only 50% moisturizer stays on the skin’s surface. Therefore, depending on dryness, it is best to reapply moisturizer 1 to 3 times daily. [7]
Are they effective?
There are several studies that suggest that moisturizers are effective in helping dry skin and repairing barrier damage, depending on how they are formulated. They are often recommended as an adjunct to other topical treatments for skin conditions like atopic dermatitis, and psoriasis.
So, yes, they are effective. If you are dealing with dry skin for any reason, it’s time to amp up the moisturizer game. [12] [13]
Is there an ideal moisturizer?
Ideal moisturizer is the one which you enjoy using every day. Additionally, if you have sensitive skin look for a fragrance, essential oil, and dye/colorant-free moisturizer.
Moisturizers usually have a mix of occlusives, emollients, and humectants.
- If your skin is normal to dry, look for a moisturizer with occlusives high in the ingredient list.
- If your skin is combination to oily, look for a moisturizer with humectants high in the ingredient list.
How to layer skincare?
Often, it is recommended to layer skin care products from thinnest to thickest consistency. There is no rule per se, the only key thing is to apply moisturizer on damp skin.
Skincare products penetrate better on damp skin and moisturizer will trap some hydration. If moisturizer is applied to dry skin, it doesn’t have any moisture to hold onto, so it won’t be that effective.
Morning skincare routine
- No morning cleanse, Sunscreen
- No morning cleanse, Vitamin C/antioxidant serum, Sunscreen
- Face cleanse, Vitamin C/ antioxidant serum, Moisturizer, Sunscreen
- Face cleanse/ Exfoliant, Vitamin C/ antioxidant serum, Moisturizer, Sunscreen
- Face cleanse, Vitamin C / antioxidant serum, Moisturizing sunscreen*
* Sunscreen can function as a moisturizer as well, just make sure you still apply enough, 1/4 teaspoon for your face.
Night skincare routine
- Face cleanse, Moisturizer, optional occlusive like Vaseline
- Face cleanse, Hydrating serum, Moisturizer, optional occlusive like Vaseline
- Face cleanse, Exfoliant, Hydrating serum, Moisturizer, optional occlusive like Vaseline
- Face cleanse, Hydrating serum, Moisturizer, Retinoid*/azelaic acid (can be used together or alone, can be layered over each other)
- Face cleanse, Azelaic acid, optional Serum, Moisturizer (if your skin is accustomed to azelaic acid)
- Face cleanse, Serum, Moisturizer, oil**, optional occlusive like Vaseline
* I do not recommend applying retinoid on damp skin, as it can cause a lot of irritation due to enhanced penetration. Also, retinoids work fine when used over a moisturizer, since they can penetrate through it.
However, do not use it over a 100% pure occlusive like Vaseline, because it won’t penetrate through it. Retinaldehyde is a very gentle retinoid and some people can tolerate it even when applied to damp skin (use caution).
** Oils are not great occlusive agents, so I do not recommend them as a substitute for a moisturizer if you have very dry skin. However, they might work fine for people with normal to combination skin.
Summary
Moisturizers are skin care products that moisten and hydrate the skin, giving it a soft and smooth feeling. They can be beneficial in repairing skin barrier damage. In addition, it can have several other benefits like anti-inflammatory, anti-itch, etc.
Three main types of moisturizers are:
- Emollients (fill in any gaps in the skin barrier)
- Humectants (draw water into the stratum corneum)
- Occlusives (form a physical barrier on the skin)
These three types are often used in combination to have a final product either a lotion, cream or an ointment. Moisturizers benefit the most when applied on slightly damp skin.
References
1. Lodén M. The clinical benefit of moisturizers. J Eur Acad Dermatol Venereol. 2005;19(6):672–688, quiz 686–687.
2. Diana Draelos Z. Therapeutic moisturizers. Dermatol Clin. 2000;18(4):597–607.
3. Lynde CW. Moisturizers: what they are and how they work. Skin Therapy Lett. 2001;6(13):3.
4. Madison KC. Barrier function of the skin: la raison dêtre of the epidermis. J Invest Dermatol. 2003;121(2):231–241.
5. Jemec GB, Na R. Hydration and plasticity following long-term use of a moisturizer: a single-blind study. Acta Derm Venereol. 2002;l 82(5):322–324.
6. Sethi A, Kaur T, Malhotra SK, Gambhir ML. Moisturizers: The Slippery Road. Indian J Dermatol. 2016;61(3):279-287.
7. Purnamawati S, Indrastuti N, Danarti R, Saefudin T. The Role of Moisturizers in Addressing Various Kinds of Dermatitis: A Review. Clin Med Res. 2017;15(3-4):75-87.
8. Rawlings A, Harding C, Watkinson A, Banks J, Ackerman C, Sabin R. The effect of glycerol and humidity on desmosome degradation in stratum corneum. Arch Dermatol Res. 1995;287:457–64.
9. Kraft N, Lynde CW. Moisturizers: What they are and a practical approach to product selection. Skin Therapy Lett. 2005;10:1–8.
10. Ghadially R, Halkier-Sorensen L, Elias PM. Effects of petrolatum on stratum corneum structure and function. J Am Acad Dermatol. 1992;26(3):387–396.
11. Rawlings AV, Canestrari DA, Dobkowski B. Moisturizer technology versus clinical performance. Dermatol Ther. 2004;17(s1)(Suppl 1):49–56.
12. Lucky AW, Leach AD, Laskarzewski P, Wenck H. Use of an emollient as a steroid-sparing agent in the treatment of mild to moderate atopic dermatitis in children. Pediatr Dermatol. 1997 Jul-Aug;14(4):321-4. doi: 10.1111/j.1525-1470.1997.tb00968.x. PMID: 9263319.
13. Draelos ZD. Moisturizing cream ameliorates dryness and desquamation in participants not receiving topical psoriasis treatment. Cutis. 2008 Sep;82(3):211-6. PMID: 18856161.
Disclaimer: This blog post is for information purposes only and does not replace medical advice.