Skin moisturizers are one of the most purchased skincare products. They serve an important function which is restoring a disrupted skin barrier, increasing its water content and preventing water loss. Moisturizers are not just for dry skin types, they are an important element in every skincare routine.
Not all moisturizers are the same and there are 3 main categories to which they belong: humectants, emollients and occlusives depending on their properties. Most products on the market contain all three categories in different proportion. Different skin types and skin characteristics may benefit more from one category of moisturizer than the others.
Table of Contents
Humectant face moisturizers
Humectants are hygroscopic molecules, meaning they attract and bind water, thus increasing moisture when applied on the skin. To avoid increased transepidermal water loss, they are usually in formulation with occlusives: as they attract water also from the deeper layers of the skin, there would otherwise be the risk of increasing the amount of water coming from the dermis into the epidermal layer and then evaporating into the air. By attracting water and plumping up the skin they also temporarily act as an antiwrinkle remedy, smoothing fine lines. Among the many molecules used in humectant skin moisturizers there are:
- Hyaluronic acid
- Glycerin (glycerol)
- Urea
- Propylene glycol
- Sorbitol
- Ammonium/potassium/sodium lactate
- Sodium hyaluronate
- Gelatin
- Panthenol
- Natural moisturizing factor (NMF)
Emollient face moisturizers
Emollients are simply oils and lipids that fill the gaps between the skin cells. Our own natural lipid matrix is supposed to do that, but sometimes it may be disrupted and cause increased transepidermal water loss. Besides decreasing TEWL, they also make the skin smoother, softer and more elastic. Examples of skin emollients in skincare products are:
- Dimethicone
- Propylene glycol
- Isopropyl palmitate
- Isopropyl isostearate
- Petrolatum
- Lanolin
- Mineral oil
- Castor oil
- Jojoba oil
- Glyceryl stearate
Occlusive face moisturizer
Occlusives are molecules that decrease TEWL by forming a protective hydrophobic film on top of the skin. Petrolatum is the most effective occlusive skin moisturizers reducing water loss by 98-99%. Lanolin is another common occlusive moisturizer, but there have been many reports of contact dermatitis following its use. Other examples of occlusive skin moisturizers in skincare products are:
- Mineral oil
- Paraffin
- Squalene
- dimethicone
- Caprylic triglyceride
- Lecithin
- Cholesterol
- Propylene glycol
- Stearic acid
Best class of moisturizer for the skin
Most formulations of moisturizers consist of a mix of all three different classes of molecules; moreover, some of them belong to more than one class by showing more than one property. Moisturizers come mainly as creams or as lotions:
- Creams are thicker and richer. They are an emulsion of water in oil. (high lipid content)
- Lotions are thinner. They are an emulsion of oil in water. (high water content)
Selecting the right moisturizer will depend upon your skin type and your needs:
- Dry skin generally requires a twice daily application, and in dryer and colder climates an extra application during the day may be beneficial. A cream may be more beneficial than a lotion or you may use a lotion in the morning and a cream at nighttime depending on your needs. A barrier repair moisturizer containing ceramides, fatty acids and cholesterol in a 1:1:1 ratio would be the best for long term results.
- Oily skin types should choose a light moisturizer (lotion type) or just use the sunscreen and no moisturizer at all.
- Sensitive skin should avoid using moisturizers that contain known irritant ingredients such as fragrances and essential oils.
- Skin prone to acne should choose non-comedogenic moisturizers.
Sources
- Fitzpatrick’s Dermatology. 9th Edition
S Kang – McGraw-Hill, 2019
ISBN 978-0-07-183783-5
https://dermatology.mhmedical.com/book.aspx?bookid=2570 - International Textbook of Aesthetic Surgery.
N Scuderi – Springer, 2016
ISBN 978-3-662-46599-8
DOI: https://doi.org/10.1007/978-3-662-46599-8 - The Art of Aesthetic Surgery – Principles and Techniques. 2nd Edition
F Nahai – CRC Press, 2011
ISBN 978-1-4822-4166-2
