What causes acne?

What causes acne?

causes acne

Acne is the most common skin complaint in the world. It is what happens when your pores get clogged and infected with bacteria. But what causes acne in the first place?

Despite its prevalence, what causes acne is actually not that well understood, and a lot of research is currently being done in order to get to the root of the problem. Currently, however, there are a number of recognized causes of acne and we will look at them in the words that follow.

The first step toward getting rid of your pimples is figuring out why you are getting them in the first place. Since there are difference causes, your treatment must be appropriate for your particular situation. Using the wrong type of treatment will cost you not only time and money, but could also irritate your skin and worsen your current breakouts.

At the root, there are really only 3 things that cause acne:

  • Skin oil (called sebum)
  • Clogged pores
  • Bacteria (Propionibacterium acnes, the bacteria which grows inside clogged pores, causing pimples)

Despite there only being 3 underlying, it goes deeper than that. What causes overproduction of skin oil? What causes clogged pores? What causes bacteria to grow in hair follicles? Answering these questions can help you understand why you may be getting acne breakouts.

Here are the most common contributing factors to the development of acne.


A group of hormones called androgens are responsible for the outbreaks that typically occur during puberty. This is because androgens are released in huge quantities during puberty[, and they cause sebaceous glands to begin producing more sebum. The P. acnes bacteria thrives on sebum, so this excess skin oil leads to increased bacteria counts within clogged pores, which therefore leads to the formation of pimples.

Adult women also experience androgen release during ovulation. It is for this reason that many women experience breakouts prior to and during their periods, and also why 54% of women over the age of 25 experience acne, compared with only 40% of men.

Anti-androgen therapies such as some forms of birth control have been shown to be effective against hormonal acne.


If your parents had this skin condition, you are more likely to get it.

It has been shown that acne is hereditary. One study looked at first-degree relatives (parents) of people with acne, compared to those without acne in order to determine if genetics was a factor in the likelihood of getting the disease. It found that patients with acne were nearly 5 times more likely to have a parent who also suffered from acne]. This shows that genetics is not only a factor, but a significant factor.

But what exactly do these “acne genes” do? How can genetics make someone more prone to developing acne?

While this is not fully understood, there are some clues. For instance, there was a study that demonstrated that sebum production in identical twins is nearly the same, whereas non-identical twins have different levels of sebum production. However, the identical twins did have different amounts of facial acne. This seems to suggest that sebum production has a genetic component, but there are other factors at play.


One of the root causes of acne is the P. acnes bacteria. There are several strains of P. acnes which are associated with pimples, and they all have a few things in common: They live deep within skin pores and they feed on sebum for energy. There are also several other bacteria which may be linked to acne, such as Staphylococcus and Corynebacterium, but a link has not been proven.

When pores become clogged, and sebum can’t escape, the P. acnes bacteria uses the excess sebum to grow out of control. This itself is not the problem. Rather, the problem is your body’s natural autoimmune response to the overgrowth of bacteria. In some people, the body “overreacts” and sends lots of white blood cells to the area. As these blood cells fight the bacteria, they release destructive enzymes into your pore, leading to damage and inflammation of the surrounding tissue. In other people, the body is not able to effectively kill the P. acnes bacteria. In this case, even more destructive enzymes and something called cytokines are released in an effort to kill the bacteria.

Fortunately, there are several ways to kill P. acnes bacteria without relying on your immune system. One option is through the use of antibiotics such as tetracycline and erythromycin. While these medications are capable of killing P. acnes, it is also possible for the bacteria to develop a resistance over time. In other words, antibiotics will become less effective the longer you use them. Another option is a topical treatment such as benzoyl peroxide. Unlike with antibiotics, benzoyl peroxide will not cause P. acnes to develop a resistance. You can keep using it for as long as your pimples persists.


Excessive washing or rubbing, sporting equipment such as helmets of straps, or certain items of clothing can all irritate skin to the point of causing breakouts. This type is known as acne mechanica, and can occur even if you are not otherwise susceptible to getting acne.

Irritation causes acne in much the same way that the P. acnes bacteria causes it: by invoking your body’s immune system into action. When the skin becomes irritated, your body sends white blood cells to the area to fight off whatever is causing the irritation. During this process, enzymes and cytokines are released and damage is caused to your hair follicles. This inflammation is what leads to the formation of acne.


It has long been suspected that there may be a link between acne and stress, but it has never been proven conclusively. Despite this, there seems to be enough evidence to suggest that they are probably linked in some way.

In 2003 a Standord University School of Medicine study examined students with acne as they prepared for class examinations. The researchers found that as stress levels rose in preparation for the exams, acne increased with it. Although this study used a small sample size of 22 students, it appears to indicate that stress does have some affect on acne. A later study conducted in Singapore in 2007 found similar results, further strengthening the claim.

The latter of the studies mentioned above found no increase in sebum production during times of high stress, only an increase in acne. This means that something else is causing the increased breakouts. While the exact mechanism is still unknown, it is thought that stress simply reduces the body’s immune response. This means that your body will have more difficulty killing any P. acnes bacteria that may be present in your pores.


The link between diet and acne has been debated for decades, and there are still no firm conclusions. However, there is enough evidence to suggest a probable link between various dietary components and pimples. There is even evidence to suggest that our western diet as a whole might be to blame. Discover here which foods can cause acne.


The consumption of dairy products is one of the dietary factors that has been thought of as causing it for a very long time. In fact, there are studies on this going all the way back to 1949.

A more recent study has shown that not only milk, but other dairy products such as cheese, sherbet, and instant breakfast drinks were linked to acne breakouts in high school students. A similar study found similar results in teenage girls.

The exact mechanism is still unknown, but it has been suggested that it may be the hormones in milk which are the root of the problem. Particularly a hormone known as IGF-1, or insulin-like growth factor 1. IGF-1 increases androgen production, which we know has been linked to increased acne.

Glycemic Index/Glycemic Load/Sugar

The glycemic index (GI) of a food is a measure of how much and how quickly the carbohydrates in that food will spike blood sugar levels. Can blood sugar levels possibly impact the severity of break outs? Several studies seem to suggest so.

Both the Academy of Nutrition and Dietetics and the Seoul National University College of Medicine have published studies showing a strong connection between high carbohydrate or high GI diets and the severity of acne.

High GI foods also appear to increase levels of IGF-1 and androgen hormone levels, which we know causes acne[.


Chocolate is one of those age-old acne myths that has been around forever, but is there anything to it?Some studies in the 1960’s and 1970’s showed no correlation between chocolate consumption.

For a while this put the myth to rest until some recent studies put the hypothesis to the test again and are showing different results[.

It appears that chocolate releases insulin, which as we know can lead to breakouts in acne-prone individuals.


Acne that is caused by cosmetics has the appropriate name of acne cosmetica. This term was coined in the 1970’s and is still around today[, although it is uncommonly used. This is largely due to improvements in cosmetics in recent years.

The mechanism of action is not fully understood, although it is believed that certain cosmetics can clog pores in the same way that dead skin cells sometimes naturally do. This traps the sebum and P. acnes inside, causing pimples.

Many cosmetic products are now labelled as being non-comedogenic, which means that the product does not contain ingredients known to cause this horrible skin condition. However, recent research suggests that it is not the specific ingredients that cause acne, but rather the product as a whole.


There are certain prescription medications which can cause it as a side effect. Some of these medications are corticosteroids, anticonvulsants, lithium, and barbituates.

Unfortunately, acne caused by medications can be more resistant to treatment than other types, and often the medications cannot be stopped.

cause of acne