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What Causes Acne?

Dr. Nancy Shannon

Medically reviewed by Dr. Nancy Shannon, MD, PhD on May 12, 2021

It helps to know what you’re up against before you try to combat it. Though a working knowledge of what causes acne isn’t absolutely necessary for those seeking treatments, it can make it easier to know what treatments may work best for you. If you’re curious about where acne comes from, here’s what you need to know: 

Acne and Pores

To understand acne, you need to understand the skin more generally first. Though acne is complicated and has multiple different types, almost all instances of it begin with the pores on your skin. Healthy pores are open, unclogged. If a pore becomes clogged, the chances for acne formation go up significantly.

So how do pores get clogged? While there are a number of different factors and materials that can affect your pores, most clogging processes begin within the pore itself. Each pore contains a hair follicle and sebaceous gland (“pilosebaceous unit”) which produce a mixture of fats called sebum. You’re probably familiar with sebum as the oily substance that can pool up on certain parts of your face. This sebum will sometimes mix with the shedding corneocytes — dead skin cells — present at the surface of a pore, which leads to the pore itself getting stopped up.

Inside most pores is a strain of bacteria called Cutibacerium acnes, or C. acnes for short (this bacteria was previously known as Propionibacterium acnes, or P. acnes). These bacteria feed on sebum, so the overproduction of oils that often precedes acne development also fuels a rise in C. acnes growth. If a clogged pore sees a spike in C. acnes, the result will often be inflammation, which can visibly be identified as a pimple or pustule located above the opening of the follicle. 

Different Acne Types and Their Causes

When a pore is clogged, you can develop whiteheads (where the pores becomes closed) or blackheads (where the pore is open and the dead skin cells become oxidized by air and appear dark). These types of acne are called non-inflammatory because the skin around instances of them does not necessarily appear inflamed (although there is microscopic inflammation going on). As mentioned previously, the bacteria contained within either black or whiteheads can eventually cause inflammation, leading to instances of inflammatory acne that appear as red pimples. 

If a pore gets clogged, the sebaceous glands will sometimes continue to produce sebum as normal, leading to an overabundance of the stuff within the pore itself. This can cause the walls of the pore to rupture and leak both sebum and C. acnes into the skin surrounding the pore. This creates the signature pressure and painful red bump that so often accompany inflammatory acne. 

This phenomenon doesn’t only occur at the surface of the skin, though. The walls of the pore can break and send sebum to the surrounding tissue without breaking through to the surface. These acne outbreaks are known as nodules (which are hard) and cysts (which can be softer and filled with pus). These nodules and cysts make up more severe forms of acne called nodulocystic acne and are more prone to leaving scars if not treated promptly. 

What about acne on different parts of the body?

Acne — whether it appears on your face, chest, back, or somewhere else entirely — is almost always caused by one of the processes described above. That being said, not all clogged pores become clogged in the same way. The sebaceous glands can be overactive anywhere, but are most commonly found producing too much oil in the “T-zone” on your face. 

Friction can also create clogged pores by constricting sweat, oils, and dead skin cells from properly escaping. This kind of acne development is far more likely to happen on the parts of your body where you wear tight clothing than on a more commonly bare part of your body such as your face. The acne itself may be largely the same, but what exactly caused it may differ based on what’s going on with that specific area of the body. 

If you’re having difficulty knowing how best to treat your acne, we’re here to help. Reach out to a member of our medical team today to learn more about what treatment options may be right for you.

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