What Causes Acne?

Top 3 Factors that Cause Acne

Acne has three causes: overactive sebaceous (oil) glands, abnormal shedding of dead skin cells, and the fast production (proliferation) of acne-causing bacteria.

All three of these factors have to be present for acne to happen.

You might be surprised that these factors are not related to what you eat or your skincare routine. That's because factors that you can't control, like your genes, contribute to acne more than your habits do.

This article will focus on the three main factors that cause acne to develop.

Why Does Acne Happen?

Many researchers believe that acne is an inflammatory skin condition. In general, acne develops because your skin is prone to it. You don't get acne because you did or did not do certain things to try to prevent it.

However, there are some forms of acne that are driven by specific factors. For example, cystic acne seems to be closely linked to hormones.

There are also some factors that don't cause acne but can make it harder to manage.

For example, your skincare habits won't cause acne. But rarely washing your face, or washing it too often, can contribute to pimples.

Using skin care products can help prevent breakouts, but using the wrong kind of product for your skin or using products with irritating ingredients can have the opposite effect.

Research has also suggested that acne can be made worse by lifestyle factors like stress and some foods and drinks. However, these factors don't cause acne to happen in the first place.

If these factors don't cause acne, what does? In general, there are three key elements to acne formation: oil production, dead skin, and bacteria.


Overactive Sebaceous Glands

Trapped oil within the pore causes blockages and blemishes. Photo: Eric's Phtotgraphy / Getty Images

Sebaceous glands are tiny glands in your skin. They make an oil called sebum. Its job is to lubricate the surface of your skin.

If you're prone to acne, your oil glands make more sebum than is needed. The extra oil stays in the pores and blocks the sebaceous duct.

The blockage in the follicle is called a comedoComedones (more than one comedo) are the starting point for all acne blemishes, like blackheads, inflamed papules, and cystic breakouts.

Different Sebum

Some research has suggested that people with acne have different sebum than people who don't have acne.

Studies have found that people with acne make sebum with higher levels of a fatty molecule called squalene and compounds called wax esters in it.

People with acne may also have lower levels of free fatty acids and linoleic acid in their sebum compared to people who don't have acne.

The differences in the sebum might create an environment that acne-causing bacteria thrive in, leading to inflamed breakouts.


Abnormal Skin Cell Shedding

Medical illustration of the skin layers.

BSIP/UIG/Getty Images

The top layer of skin is called the epidermis. This layer constantly sheds dead skin cells through a process called desquamation. This is how the skin exfoliates and renews itself.

The epidermis has several layers. New skin cells are made in the deepest layer of the epidermis called the stratum germinativum.

The new cells slowly travel up through the epidermal layers until they reach the outermost layer called the stratum corneum

By the time the cells get to the stratum corneum, they're flat and dried out. At this point, the cells are essentially "dead." 

The dead skin cells continually fall away from the stratum corneum and are replaced by new cells that push up from below. 

However, if you have acne-prone skin, the desquamation process doesn't work well. You end up making more skin cells than people without acne do.

Lamellar Granules

People prone to acne also have fewer lamellar granules in their skin than people who don't have acne.

Lamellar granules are found in the cells of the stratum corneum. They release enzymes that digest the substance that holds cells together.

Acne-prone skin produces more dead skin cells than normal. Since those cells do not shed properly, they stay stuck in the follicle and block it.



Propionibacteria acnes

Centers for Disease Control and Prevention

Propionibacterium acnes (P. acnes) are bacteria commonly found on the skin. In some people with acne, the P. acnes population grows out of control.

P. acnes or C. acnes?

In 2018, P. acnes was renamed Cutibacterium acnes (C. acnes). Both names refer to the same bacteria.

When a pore is clogged by dead skin cells and sebum, oxygen cannot get into the pore. This is called an anaerobic environment.

Some bacteria, like P. acnes, thrive in anaerobic conditions. In a plugged pore, their population can grow quickly.

The bacteria make a fatty acid waste as they digest the oil trapped in the pore. The waste irritates the lining of the pore, which causes redness and inflammation.

White blood cells rush to the pore in response to the inflammation. When they die, they mix with dead skin cells and make pus. This is what gives a zit a whitehead appearance.

Experts think that P. acnes isn't the only bacteria that causes acne. Instead, it works with other bacteria to make the skin into an environment where acne can develop.

Having these bacteria on your skin does not mean it's dirty. Washing your skin won't make the bacteria go away.


Acne has three main causes: too much oil production, not shedding dead skin cells, and too much of a specific bacteria on the skin. All three of these factors have to be present for acne to develop.

People can also be more prone to acne because of their genetics. Contrary to popular myths, lifestyle factors like diet and skincare do not cause acne. However, they can worsen it.

A Word From Verywell

You might wonder why diet, skincare routine, and habits like touching your face didn't make the list of acne causes.

We used to think that these things were major players in acne, but now we know that's more myth than fact.

That said, just because your skin is prone to breakouts doesn't mean there's nothing you can do. If you have mild acne, over-the-counter (OTC) acne products might be enough to clear up your skin.

However, if OTC products haven't worked or your acne is severe or inflamed, make an appointment with a dermatologist. There are also prescription medications that can treat acne.

16 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Angela Palmer
Angela Palmer is a licensed esthetician specializing in acne treatment.