Monday Beauty Vocab: Humectants + Emollients + Occlusive Agents = Moisturizer!

Everything you ever needed to know about what a moisturizer is, how it works, and what to choose.
Publish date:
October 14, 2013
moisturizers, ingredients, SkinCeuticals, vocabulary, humectants, Emollients, Occlusive agents

Hello xoVain! Welcome to my new feature, Monday Beauty Vocab. Here we can discuss terms, concepts, and ingredients from the beauty world. You’ll find answers about what something is, how it works, and why it is used in the cosmetics industry.

The idea is to create a deeper discussion about the ingredients, concepts, and techniques to help you think about the makeup, fragrance, and skincare that you use in your daily life; the goal is to make a real difference in how you experience and enjoy your cosmetics.

Our first topic is one of particular relevancy to our northern-hemisphere readers. Winter is coming – and with it, cold temperatures and dry air. Where I’m at in southern France, winter is already here and I’m very grumpy about it. This is a great time to talk about the best way to protect your skin from wintry air: moisturizers.


In the cosmetics world, a moisturizer is a topical product designed to maintain optimal levels of oils and water in the skin. The product might be a cream, a lotion, a serum, or an oil.

There are thousands of different moisturizing products. Some are tailored to a time of day, like morning or night; some are designed for a particular skin type, like dry skin, combination skin, or oily skin; some are for a skin condition, such as oily or combination skin that has become dehydrated, skin prone to redness or rosacea, etc.

Each moisturizer is made of a balance of three types of ingredients: humectants, emollients, and occlusive agents. The character of a moisturizer is determined by the concentration and type of these three elements.


A humectant is an ingredient that draws water molecules out of its environment towards itself. If you are wearing a moisturizer with a humectant ingredient, it is actively sucking water from the air around you and sticking it onto your face. This helps rehydrate the skin’s surface, but can cause some irritation to the skin in high concentrations.

The classic humectant is glycerin. You might see it listed as glycerol, which is its alcohol form, on an ingredients list. Glycerin was first popularized as a byproduct of soap production. When soap makers were first able to isolate glycerin from the soap-making process in the late 1800s, they started creating more profitable lotions and creams. Glycerin is cheap and plentiful and you see it in many different moisturizing products.

Another humectant is my favorite, hyaluronic acid. Like glycerol, hyaluronic acid is found in the human body as a connective tissue. It’s an exponentially more effective humectant than glycerin and is less sticky and sweet-smelling when used in cosmetics. However, it is much more expensive.

Other humectants you might see include sodium pyrrolidone carboxylic acid, sodium lactate, urea, lactic acid, sorbitol, and butylene glycol.


An emollient is an ingredient that smooths the skin’s surface by filling in cracks between skin cells. They make the skin more soft and flexible and contribute to the creamy texture of a moisturizer. However, they are not always effective or long-lasting.

There are many emollients used in cosmetics, most of which are oils or lipids. Some emollients are stearic, linoleic, lauric, oleic, linoleic, and ceramides.


Occlusive agents are the ingredients in skincare that form a film on the skin and prevent water loss through the skin. They can be very effective, but can feel waxy or greasy on the skin and cause acne or folliculitis.

The classic cosmetic occlusive agent is petrolatum, or petroleum jelly. It is a byproduct of petroleum products and was first used as a cosmetic ingredient in the late 1800s. It is the most effective occlusive agent, capable of blocking 98% of water loss from the skin.

Other occlusive agents include lanolin, zinc oxide, and silicones. Some oils, like castor, mineral, and jojoba oil, work as both emollients and occlusive agents.


The vast majority of anti-aging creams are simply moisturizers. If you see a claim like, “Clinically proven to reduce the signs of aging” or “97% of women reported smoother, less wrinkled skin,” they usually come from self-reported trials done by the company’s R&D on a very small number of volunteers.

The volunteers are asked to avoid moisturizers for a week, which dehydrates the skin and dramatically increases the depth and number of fine lines and wrinkles. Then, after using the new anti-aging product, the volunteers are asked if their skin looks and feels better. It undoubtedly does, since moisturizers are the very best way to visually plump up the skin. This self-reported data is then communicated as a “clinical trial” to the consumer.

In reality, if a product does not contain retinoids or alpha-hydroxy acids, it does not really reduce wrinkles. Those two ingredient groups are the only ones that have a measurable impact on the behavior of the skin.

A lot of the more classic luxury anti-aging creams and serums are essentially just cheap mineral oil and glycerin with lots of plant extracts to sound fancy. The same technology can be had for a fraction of the price at the drugstore.

But if you are interested in visually reducing the appearance of wrinkles and fine lines, there is nothing better than a good moisturizer tailored to your skin type and condition. Replacing lost oils and water adds so much life and plumpness to your skin, it can be astounding.


Moisturizers can also be tailored to particular skin types and conditions. By changing the balance of humectants, emollients, and occlusive agents, you can come up with a moisturizer that addresses particular concerns.

Dry skin, for example, lacks oil. Skin tends to become drier as we age. Moisturizers for dry skin have a higher level of emollients to help fill in the lipids layer on the skin. Dehydrated skin, on the other hand, is skin of any type that lacks water. This can be addressed by a higher level of humectants or occlusive agents to attract and seal in water to the skin.

Personally, I have acne-prone skin that has been dehydrated by the use of exfoliants like tretinoin and alpha-hydroxy acids. So I look for a product that has a higher concentration of a humectant, a lower concentration of an emollient, and no occlusive agents in order to draw water to my skin without adding too many lipids or blocking my pores. I use SkinCeuticals Hydrating B5 Gel, which is just hyaluronic acid dissolved in water with vitamin B5 as an emollient.

The wonderful thing about moisturizers is that don’t have to be expensive to work perfectly well for you. Chaya, for example, uses a simple, inexpensive moisturizer--Lubriderm--and it works great for her. It’s got glycerin as a humectant, mineral oil as an emollient, and petrolatum as an occlusive agent. Simple, classic, and effective.

When you’ve found a moisturizer with the right ingredients for you, your skin will feel plump and hydrated. You’ll enjoy the texture and the application gesture (no pilling, for example!) The fragrance will lift your spirits, or there will be no fragrance at all. The price will be correct for your budget.

It’s the best winter beauty booster in existence.

If you are wondering about how something works, how to choose a particular product, or what a term means, please let me know. I'm here for you!