Moisturizers are one of the most important product groups for skincare. Moisturizers are applied to the skin to promote, restore, and maintain the hydration balance of the skin. They may contain a combination of ingredients. Thus in this post, I want to share what moisturizers contain and how they work in skin hydration.
Normally, a moisturizer is formulated with humectants, emollients, occlusives, and/or other agents in combination with water to provide hydration for the stratum corneum.
Humectant: Attract and retain water from the lower layer of the skin (dermis) and from the environment (skincare products). They bind to water via the formation of hydrogen bonds between themselves and water.
How humectant works in the stratum corneum:
Cosmetic formulation: Principle and Practice (Benson, H., Roberts, M., et al., 2019).
Some examples of humectants that you can look for in your moisturizer: glycerin, propylene glycol, urea, hyaluronic acid, sorbitol, pyrrolidone carboxylic acid (PCA), alpha hydroxy acid (AHA), elastin…
Emollient: Hydrophobic compounds that provide an occlusive layer to prevent water loss, and also help smooth skin by filling space between skin’s corneocytes.
Cosmetic formulation: Principle and Practice (Benson, H., Roberts, M., et al., 2019).
Some examples of emollients: fatty acids esters such as isopropyl palmitates, isopropyl isostearate, glyceryl stearate, myristates…,
Cholesterol, squalene, ceramides, silicone fluids (cyclomethicone), plant oil, mineral oil, shea butter…
Occlusive: Prevent water loss by forming a film layer and increasing the stratum corneum thickness.
Cosmetic formulation: Principle and Practice (Benson, H., Roberts, M., et al., 2019)
Some examples of occlusives: petroleum, lanolin, paraffin, wax, fatty alcohol such as cetyl alcohol, stearyl alcohol…
*NOTE: some agents can act as more than one mechanism thus they can be classified as emollient or occlusive (for example mineral oil).
Moisturizers also contain mild surfactants (act as enhancers) which help the active ingredients penetrate into the skin better.
Thus when choosing your moisturizer, you should be familiar with those listed ingredients and depend on your skin type to choose suitable products.
If you have dry skin:
Your skin does not produce enough oil due to gene-related issues, stress, and weather…, thus you need products with emollients (they sink into skin structure) and occlusives (block water evaporation).
If you have dehydrated skin:
This is a skin condition due to over-exfoliation, over washing leading to the water loss…, thus you need products with more humectants.
For oily skin, you will avoid products with a lot of occlusives (which may block pores…)
Of course, the products used for specific types of skin are always indicated on the label. But it is good to know what they are formulated of, isn’t it?
Reference
Cosmetic formulation: Principle and Practice (Benson, H., Roberts, M., et al., 2019).
