Is Oilier Skin More Prone to Acne?

Human skin, all over the body but particularly on the face, is covered by an oil called sebum. Sebum is produced by glands attached to each skin pore. After the glands produce sebum, it slowly makes its way up the pore and is released onto the surface of the skin.¹

Humans produce different amounts of sebum and thus have skin types, ranging from dry to oily. Conventional wisdom suggests that oily skin is the skin type most prone to acne, and there is ample scientific evidence to back up this assumption. However, the likelihood of developing acne depends on more than just the amount of skin oil present.

The Function of Sebum

Sebum is not necessarily a bad thing. It helps prevent water loss from the skin, defends the skin from microorganisms, and can aid in preventing some types of skin inflammation.

However, too much sebum can lead to more acne, especially if the sebum has a skewed composition which causes it to irritate the pore. Exactly how the composition of sebum contributes to acne is unknown, but as we'll see, we do know that the more total sebum someone has, the more that person is usually susceptible to acne.

Skin Types

There are four major skin types:

1. Dry
2. Normal
3. Combination
4. Oily

Dry, normal, and oily skin are all pretty straightforward. They are what they are. However, people with combination skin have dry, normal, and/or oily skin in various areas on their face. The most frequent case with a combination skin type is that a person will have oily skin on their forehead, nose, and chin (called the T-zone) but have normal or dry skin on their cheeks.²

Skin Oil Measurement

How do you know what type of skin you have? Individual skin type is usually measured simply by subjective personal assessment. This means that a person decides on their own whether their skin looks and feels oily, dry, normal, or a combination of these types. This is not an accurate method, though. Opinions of skin oiliness may differ from person to person, and objective methods of assessment are needed for scientific research. As one prolific acne researcher stated, "…an individual's feelings on the topic of facial sebum secretion are too subjective, and significant discrepancies exist between such subjective descriptions of facial skin type and objective measurements. Thus, facial skin type determinations should be performed using objective measuring devices and guidelines for skin typing."²

Fortunately, there is an objective, scientific method of measuring skin oil amount. This is done with a device called a Sebumeter.³ This helps determine exact skin oiliness levels and is critical for scientific studies on skin oiliness. However, very few people ever have the opportunity to get a Sebumeter reading, so in the real world, determining your skin type really does come down to subjectivity.

The way a Sebumeter works is relatively straightforward. First, a translucent strip is pressed against the patient's skin for 30 seconds. This strip will absorb sebum and become transparent. The more sebum the strip absorbs, the more transparent it becomes. The Sebumeter then measures the transparency level of the strip and translates this amount of transparency into something called the casual sebum level (CSL). The CSL is measured in micrograms per square centimeter (µg/cm²) and is used to define specific areas of the skin as dry, normal, or oily. The CSL ranges for each of these skin types in different facial areas are defined in the table below.² If readings come back different on different areas on the face, that means someone has combination skin.

What Is the Evidence That Oily Skin Is More Prone to Acne than Normal Skin?

A number of studies performed have all strongly supported the connection between increased skin oil production and acne development.^4-7 In other words, more skin oil really does mean more acne. However, the exact way in which sebum production causes acne is still unknown.

Increased Sebum Production Is Not the Only Factor That Contributes to Acne

Every study above found that increased skin oil production is associated with acne. However, inflammation, bacterial colonization on the skin, and increased skin cell growth also contribute to acne development.⁸

All of these other circumstances, including sebum production, can influence each other. For example, increased sebum production can stimulate the growth of acne bacteria, and acne bacteria can help to trigger inflammation.

The exact sequence of these events is still unknown, and we do not yet understand the exact way in which each of these factors influences acne development. But one thing research agrees on is that oilier skin is more prone to acne.