When you design a regimen for your patients, every step matters. I have heard doctors say, “Use any moisturizer that you have at home,” and I cringe. This is because the moisturizer that your patients use dramatically affects the efficacy and side effects of the other products in their skin care regimens. For enhanced results, select a moisturizer for each patient based on his or her skin type, condition, and the treatment product(s) in the regimen.
Moisturizers and Ingredient Efficacy
Moisturizers do play an important role in skin hydration and appearance, but their role in the effectiveness of the overall skin regimen is much more involved. Every ingredient in moisturizers affects the efficacy of the other products in the regimen by affecting pH, the skin barrier and the chemical structure of various ingredients. Moisturizers regulate the penetration of other topical ingredients which changes the efficacy and the incidence of side effects.
Ingredients like oleic acid and hyaluronic acid increase the absorption rate of ingredients that are applied before and after by creating tiny holes within the skin. This can be both beneficial and detrimental to the overall regimen, depending on the skin type and ingredients. For example, anti-aging ingredients such as peptides have trouble penetrating the skin. Therefore, a moisturizer that contains oleic acid or hyaluronic acid can increase the absorption of peptides into the skin and enhance their benefits. Retinoids, on the other hand, can cause dryness and flaking in sensitive skin types, so you do not want to increase the penetration of these ingredients in patients with rosacea.
Moisturizers that contain occlusives form a protective seal on top of treatment products. This not only helps to increase penetration by forcing the product into the skin, but it also keeps the treatment product from being wiped off the skin or rubbed off onto a pillowcase or sheets overnight. Moisturizers that include humectants may pull water onto the skin and dilute or enhance the effectiveness of the ingredient.
Effect of Fatty Acids in Moisturizers
I am certain that you have heard that the best moisturizers contain an equal 1:1:1 ratio of fatty acids, cholesterol and ceramides. However, less discussion is made about the type of fatty acid that is best in a moisturizer. Choose a moisturizer with stearic acid as the predominant fatty acid because it works better with ceramides and cholesterol to strengthen the skin barrier. Avoid oleic acid (this is in oleic oil) unless you want to weaken the skin barrier and increase penetration.
The Skin Barrier
The skin barrier is made up of fatty acids (green), cholesterol (purple) and ceramides (orange) to form a watertight coating around skin cells.
The above image shows the ideal skin barrier (with stearic acid) with minimal space between the lipids. However, the structure of the skin barrier is affected by which fatty acids are present.
Oleic acid increases penetration as compared to the fatty acid stearic acid. This is because the “legs” on the fatty acids chains of stearic acid are closer together than those of oleic acid and can pack more closely together, making the skin barrier stronger.