By Fayne Frey, MD – Board Certified Dermatologist
What is the purpose of moisturizer?
Some of my patients seem to think our skin absorbs water from moisturizers. The reality is moisturizers help skin stay moist by providing an environment that minimizes water loss from the skin.
Things aren’t always what they seem.
For example:
Koala bears aren’t bears.
Chinese Checkers is not a form of checkers nor did this game originate in China.
Jellyfish aren’t fish. Neither are starfish for that matter.
Peanuts aren’t really nuts.
And moisturizers don’t add water to the skin.
You may wonder why I gave you the above information. I’m trying to make a point.
It’s a good thing our skin doesn’t absorb water.
Think about it; if our skin could absorb water like a sponge, we would all swell up like giant blueberries every time we swam in the ocean. Built like a brick wall, the outermost layer of skin serves as an incredible barrier. This waterproof layer protects us from outside elements including bacteria, mold, fungus, and the sun’s ultraviolet rays. Our hands do not swell when we scrub dishes after a meal. Once dry, our hands look the same as before we washed the plates. Our skin prevents the body from losing water as best it can, though water constantly evaporates from our bodies into the environment. We lose less water on moist humid days than on cold days, which is why our skin may feel drier in the winter.
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Let’s be clear; effective moisturizers do not add water to the skin.
What moisturizers do is create an environment where water loss from the skin into the air is minimized. Decreasing the amount of liquid that evaporates results in an increase in skin water content. Well-formulated “moisturizers” contain ingredients that form a film on the skin surface to prevent water evaporation called occlusives. Petroleum jelly is an effective occlusive that decreases water loss from the skin into the environment by 98%. However, not everyone likes to use petroleum jelly because it can feel greasy on the skin.
Ingredients called silicone derivatives are used often in lieu of petroleum jelly, or in addition to it, to improve the feel of the product, though they do not prevent water loss from the skin as well. Effective moisturizers may contain additional ingredients as well, known as humectants, to help the skin hold onto water, the real purpose of moisturizer.
The Bottom Line
Even the best moisturizers do not add water to your skin. In fact, they don’t really moisturize at all. The skin does that on its own. So what is the purpose of moisturizer? It creates an environment that allows the skin to hold onto its own water. Perhaps it would be more appropriate to call these types of products fortifiers or protectants, though we know “moisturizer” is a name that works in terms of marketing. At the end of the day, companies want to sell their products.
By the way, fireflies aren’t really flying. And strawberries aren’t really berries.
Fayne Frey, M.D.
Commonly known as the Ralph Nader of the skincare industry, Dr. Fayne Frey is a New York-based, Ivy-League trained, board-certified dermatologist nationally recognized in the effectiveness and formulation of over-the-counter skincare products.
Dr. Frey is a contributor to and on the editorial board of both 50PlusToday and The Doctor Weighs In, one of the leading online resources for trusted health and wellness information. She is a frequent speaker in many venues where she captivates audiences with her wry observations regarding the skincare industry. She has consulted for numerous media outlets, including NBC, USA Today, and the Huffington Post, and has also shared her expertise on both cable and major TV outlets.
Dr. Frey is the Founder of FryFace.com, an educational skincare information and product selection service website that clarifies and simplifies the overwhelming choice of effective, safe, and affordable products encountered in the skincare aisles.
Dr. Frey is a graduate of Boston University, summa cum laude with Distinction, a member of Phi Beta Kappa and a graduate of the Weill Cornell Medical College. She is a fellow of both the American Academy of Dermatology and the American Society for Dermatologic Surgery.
In her spare time, you might find her running, playing piano, reading, or eating M&Ms. Dr. Frey lives in Rockland County, NY with her husband and has four grown children.
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originally posted 11/25/2019
updated 6/8/2023
