Know Your Skin: The Science of Skin Types, Your Ultimate Guide

written by Allison Goins, Ph.D. | Published on March 9^th, 2024 at 12:00 pm

Have you ever watched someone review a skincare product; they rant and rave about how amazing it feels, the wonders it has worked on their skin and you are convinced to buy it? And if it is coming from a person that you trust for recommendations because they have a similar skin type as you or struggle with similar skincare concerns it honestly seems like a no-brainer.

Or you are browsing a brand’s website and it says this product was specially formulated for your skin type. But once you have it and use it there is instant buyer’s remorse. Your skin does not like it, at all; or it just does not give you the feel-good feeling you expected.

Skin types like almost every other broad grouping can be helpful as a starting point,. However, your skin is a dynamic living organ, and a one-time classification may not fully arm you with the information you need to make the right skincare decisions. But skin type categories provide a great foundation to build your skincare routine.

Skin types are broad categories that describe the way your skin behaves. And since these categories are generally helpful, brands use them to formulate products. Whether it is to help compensate for hydration deficiencies or calm your overactive sebum glands. So let’s talk about the science of skin types, and how knowing what it means on the cellular level can help empower you to make better decisions.

Understanding Your Skin’s Structure

To understand what contributes to your skin type it is important to understand the structure of your skin. And while you may think of your skin as a protective stretchy layer that is wrapped around your body it is actually so much more complex than that.

Your skin is made up of three layers. The epidermis, dermis, and subcutaneous layer. And each of the layers has its own important function.

Epidermis: The outermost layer is responsible for protecting your body from the outside world.
Dermis: Often called the “command center,” contains cells crucial for keeping your skin healthy and youthful.
Subcutaneous layer: Like internal packing peanuts, this layer cushions and protects your organs, bones, and muscles.

And each of these layers play a role in your skin type.

Demystifying the Major Skin Types

The American Academy of Dermatology says there are five major skin types normal, dry, oily, combination, and sensitive.

A survey of approximately 900 people in Southeast China ranging from ages 18-81 showed that the Normal/ Combination, Dry, and Oily skin types made up roughly an even 1/3 spilt of the participants. Its a little unfortunate they combine normal an combination skin in this study so we ca not tell the exact break down. However, normal skin is the most rare skin type.

One of the most important things to remember about your skin type is that is can change. Oily skin was most prevelant in the youngest age group, 18-29 years old around 40% and it decreased to 20% in the mature age group, 50-81 years old. In the mature age group, dry skin made up roughly 50% of the group and this makes sense for reasons we will talk about once we deep dive into dry skin.

Classifying Skin Types, The Science Behind How Your Skin Behaves

Skin types are classified by three characteristics:

Hydration
Oil Production
Reaction to Products

What Affects How Hydrated Your Skin Feels?

Your epidermis is the layer of your skin that primarily controls your skin’s hydration. Specifically the outermost layer of your epidermis, the stratum corneum is a barrier keeps water in the lower layers of your skin. Often you will hear people reference transepidermal water loss (TEWL). This term describes how much water is able to travel through your epidermis and out of your skin. When your epidermis is healthy it acts as a barrier and prevents the majority of water from escaping the lower layers of your skin.

All of your cells hold onto water. The total water content present in your skin cells is another measurement of skin hydration. Increasing your water intake or using a topical hydrator permeates the cells with water and improves your skins ability to absorb moisture.

What Controls the Oil Production in Your Skin?

Your dermis is the layer of your skin that controls oil production. Sebum, an oily substance produced by your sebaceous glands. Your sebaceous are located in your dermis, and play a vital role in keeping your skin healthy and protected. It even affects your skin’s ability to hold onto water.

The sebaceous glands are tiny factories nestled within your pores, responsible for churning out sebum. These glands are particularly concentrated in your T-zone (forehead, nose, and chin), which explains why these areas tend to be oilier. But what dictates how hard these factories work? Hormone levels signal the sebaceous glands to ramp up production, leading to oilier skin.

While hormones are the primary drivers, other factors can influence sebum production. Here are a few to keep in mind:

Age: Sebum production naturally decreases with age. As your skin slows down its production of important structural proteins like collagen and elastin; it also slows down producing sebum.
Climate: Hot and humid environments can trigger increased sebum production, while cold, dry climates can have the opposite effect.
Genetics: Some people are simply predisposed to oilier skin due to their genetic makeup.
Diet: While research is ongoing, some studies suggest a link between your sugar intake to oil production

How Skin Types Affect The Way Your Skin Responds to Products?

Your epidermis and dermis both contribute to the way your skin responds to products. Healthy skin acts as a gatekeeper, with the outermost layer (stratum corneum) filtering out potential irritants. However some irritants are small enough to permeate through your skin barrier and this is when the cells in your dermis will attack them.

However, a damaged skin barrier or genetics can make you have a weaker barrier, allowing some ingredients to penetrate deeper and trigger reactions. Sensitivity to ingredients can be an immune reaction. The same way people have allergic reactions to food you can have an allergic reaction to skincare ingredients.

Decoding How the Skin Types Are Related to Biology

Now that we’ve talked about the biology that contributes to your skin’s hydration, your skin’s oil production, and your skin’s reaction to products let’s talk about how each of the skin types fits into these categories.

Normal Skin

Normal skin is characterized by a very balanced response to all of those questions. After you wash your skin if you were not to put any products on your skin after about 30 minutes it would not feel greasy or tight. Additionally typically you are not going to have a lot of breakouts or flakiness. Typically a person with normal skin is also able to tolerate most products. While you may not like the feel of them they are not going to cause stinging, burning, or redness.

Here’s how normal skin typically responds:

Hydration: Skin typically feels hydrated, you are not typically going to deal with flaking or dry patches.
Oil Production: Balanced, your skin cells produce enough oil to retain moisture, but not enough that you will notice shininess on your face.
Response to Products: You should be able to tolerate most products. After using products you will not typically experience stinging, burning, or redness.

While you may genetically have normal skin there are a lot of external factors that can cause your normal skin to not feel hydrated, overly oily, or sensitive to products. Typically your environment, water intake, and product usage can throw the typical “balance” of your skin.

Dry Skin

Dry skin craves hydration! It often feels tight and rough, especially after cleansing. Imagine washing your face and 30 minutes later it feels very tight or like sandpaper – that’s a telltale sign of dryness. Dry skin can also be flaky or scaly, and may even be prone to irritation or redness. Understanding this science behind dryness will help you navigate product claims and find ingredients that effectively replenish your skin’s moisture barrier.

Here’s how dry skin typically responds:

Hydration: Skin typically does not feel hydrated, you will often find yourself dealing with flaking or dry patches. This can be related to a compromised barrier or genetically having a more permeable barrier.
Oil Production: Lower oil production, your skin cells may not be producing enough oil to retain moisture. You are not going to notice shininess or a ton of oil on your skin.
Response to Products: While you may be able to tolerate most products; you are going to want to use moisturizing products. If a product is stripping or dehydrating then your skin could feel very tight and irritated after using it. This typically happens with cleansers.

Dry skin can be genetic, but it can also be created by using products that are overly stripping or over exfoliation. When you do this, you can damage your skin barrier which leads to excessive TEWL and sensitivity. Similar to normal skin your environment can also affect your skin.

Oily Skin

Oily skin can feel like a constant battle with shine and acne. This skin type is characterized by overactive sebaceous glands, which produce an excess of sebum. If you wash you face and wait 30 minutes before applying products you skin will be shiny. Your overactive sebaceous glands makes your skin look and feel greasy, and sometimes enlarged-pore appearance. Oily skin can also be more prone to breakouts, as excess oil can trap dead skin cells and create a breeding ground for bacteria. But here’s the good news: oily skin tends to age slower due to its natural moisture levels. By understanding the science behind oil production, you can find targeted products that control shine without stripping your skin’s natural balance.

Here’s how oily skin typically responds:

Hydration: Skin typically feels hydrated, due to the overproduction of oil in your skin you are not going to often struggle with dehydration.
Oil Production: Excessive oil production, your skin cells go into overdrive producing oil. You are typically going to have a ton of oil on your skin. Your pores also may appear enlarged because they are filled with sebum.
Response to Products: While you may be able to tolerate most products; you are going to want to products that are designed to be a little more stripping. If a product is stripping then your skin could feel a lot cleaner and it can help cut down on acne.

Oily skin is typically genetic or can be related to hormones. As you age you skin cells slow down and so does your oil production. Finding a balance between using exfoliants to help clean your pores versus over exfoliating your skin and causes your skin to be sensitized is a delicate balance you have to strike. Additionally it can be a common trap for people with oily skin to want to avoid moisturizing because they do not want their skin to be oily. However if your skin is dehydrated this can actually trigger your skin to produce more oil. So find products that make your skin feel good.

Combination Skin

Combination skin can feel like you’re living in two different zip codes – one oily, one dry! This common skin type is characterized by having an oily T-zone (forehead, nose, and chin) and drier cheeks and jawline. You might experience shine and enlarged pores in your T-zone, while your cheeks feel tight or flaky, especially after cleansing. The science behind combination skin likely involves variations in sebum production across different facial areas and sensitivity.

Here’s how combination skin typically responds:

Hydration: Your cheeks might feel tight or flaky, especially after cleansing, indicating dryness. However, your T-zone often feels shiny and greasy due to excess oil production.
Oil Production: The T-zone’s sebaceous glands are overactive, pumping out excess sebum, leading to shine and potentially enlarged pores. The cheeks, on the other hand, have less active sebaceous glands, making them prone to dehydration.
Response to Products: Finding the right balance is key. Harsh products can irritate the dry areas, while overly rich moisturizers might clog pores in the T-zone. Look for gentle cleansers and oil-free moisturizers for your whole face. Targeted treatments, like a light moisturizer for cheeks and a toner for the T-zone, can further address specific concerns.

Combination skin can be influenced by genetics and hormones. The good news is that as you age, oil production naturally slows down, potentially minimizing the contrast between your T-zone and cheeks. Dehydration in the dry areas can actually trigger your T-zone to produce more oil. Focus on finding products that address both concerns, keeping your skin comfortably hydrated and shine-free throughout the day. Remember that you don’t need a separate routine for the difference regions of your skin, you can find products that. Brands understand that skin types are dynamic and typically formulate products to be versatile.

Sensitive Skin

Sensitive skin is all about reactivity. Unlike other skin types, sensitive skin reacts more readily to various triggers, which causes more products to make your skin feel irritated. This irritation can manifest itself as redness, stinging, burning, or even itching after using certain products. While there are people that have sensitive skin there are a lot of people that have sensitized their skin. The science behind sensitized skin often involves a weakened or compromised skin barrier, which allows irritants to penetrate more easily. Understanding this vulnerability will help you choose gentle, fragrance-free products and develop a calming skincare routine that prioritizes soothing and strengthening your skin’s natural defenses.

Here’s how sensitive skin typically responds:

Hydration: Sensitive skin can be prone to both dehydration and flare-ups. Dryness can compromise the skin barrier, making it more vulnerable to irritation. However, some humectants or moisturizers that work well for others might trigger a reaction.
Oil Production: Oil production in sensitive skin can be normal or slightly lower. However, the focus isn’t necessarily on controlling oil, but rather on maintaining a healthy skin barrier that functions optimally.
Response to Products: Sensitivity is the hallmark of this skin type. Harsh ingredients, fragrances, and even some common actives can trigger reactions. This makes choosing products a careful process, with a focus on gentle, fragrance-free formulas.

Understanding these sensitivities is crucial. By listening to your skin’s response and opting for calming, non-irritating products, you can create a skincare routine that soothes and strengthens your skin’s natural defenses, allowing it to thrive.

Demystifying Your Skin Type for a Flawless Routine

Skin type goes beyond a simple label. It’s a reflection of your skin’s biology, influenced by factors like hydration levels, oil production, and sensitivity. Understanding these scientific underpinnings empowers you to make informed choices about your skincare routine.

Key Takeaways about Skin Types:

Hydration: Each skin type experiences hydration differently. Dry skin craves moisture, while oily skin tends to be naturally more hydrated. Combination skin presents a mix of both.
Oil Production: Sebaceous glands play a key role, with hormones and genetics dictating oil production. Oily skin has overactive glands, while dry skin might have lower production.
Sensitivity: This skin type reacts more readily to various triggers due to a potentially compromised skin barrier.

Why Understanding Your Skin Type Matters:

Knowing your skin type is the foundation for building an effective skincare routine. By choosing products that target your specific concerns – hydration, oil control, or calming sensitivity – you can address your needs and achieve optimal results.

Taking it a Step Further: Consult a Dermatologist About Skin Types

While this article provides a helpful overview, a dermatologist can offer personalized advice based on your unique skin. They can assess your skin type, recommend tailored products, and address any specific concerns you might have.

Remember, healthy, glowing skin is achievable! By understanding your skin type and its underlying science, you can embark on a journey toward a personalized skincare routine that keeps your skin happy and thriving

References

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