Acne, at its most basic, is the blockage of the tiny openings in the skin, called pores. Acne is caused by three major factors: abnormal shedding of skin cells, overactive sebaceous (or oil) glands, and a proliferation of acne-causing bacteria. These factors can be triggered by hormonal changes within the body, which explains why acne is most common at certain life stages: puberty, pregnancy, perimenopause, and menopause.

Common Causes

For being the most common skin condition in the United States, affecting nearly 50 million people at any given time, it is a remarkably misunderstood condition. This is partly attributed to the fact that it’s a complex condition. The following factors all often have to come together to produce acne.

Physiological Factors

Three major physiological acne-causing factors have to come together in order for acne to develop:

  • Overactive sebaceous glands: Most people attribute acne to oily skin. Our skin has glands, called sebaceous glands, that create oil to keep the skin lubricated. This oil is called sebum. Sebum on the surface of the skin isn’t the issue; it’s when sebum becomes trapped inside the pore that a blockage is created. It’s important to know that even people with dry skin can have acne. It’s the oil that is down in the pore that causes blockages (comedones).
  • Abnormal shedding of dead skin cells: Throughout your lifetime, your skin is constantly renewing itself by creating new skin cells and sloughing away the old. This process is called cell turnover, or desquamation. In skin that is prone to acne, this cell turnover process isn’t happening properly. Instead, more skin cells than typical are being created, and they are hanging around for longer than needed. This is called retention hyperkeratosis. These excess skin cells clog up the pores, also creating comedones.
  • Proliferation of acne-causing bacteria: The third factor that creates an acne condition is a glut of acne-causing bacteria, Propionibacteria acnes, within the pore. This bacteria is a normal resident of the skin, and not at all an indication of uncleanliness. For people with acne, though, there are more of these bacteria on the skin and the skin is more sensitive to them. These bacteria irritate the skin, causing inflammation which we see as inflamed pimples.

The Role of Hormones

We know that acne isn’t around for your entire life. Your skin, at some point, was clear. Why then does acne seem to suddenly appear? In a word: hormones.

Androgen hormones, specifically testosterone, stimulate the sebaceous glands to swell and produce more oil. There is indication that androgens also make the pore a more favorable home for acne-causing bacteria. Estrogen and progesterone also play a role in acne development, considering that acne is also common during pregnancy and menopause, but the exact influence they have on the sebaceous glands isn’t as clear.

Hormones play a huge role in acne development. The major players here are androgen hormones: estrogen and testosterone.

Simply put, if the three trigger factors are present in the skin, hormones are the match that ignites acne development.

Less Common Causes

Although these aren’t considered primary causes of acne, these may trigger or exacerbate breakouts for some people. They include:

  • Topical cosmetics (products like makeup, moisturizers, sunscreen, and the like that clog pores, causing a type of acne called acne cosmetica)
  • Sweat
  • Heat and friction (this can cause a type of acne called acne mechanica)
  • Certain drugs (including birth control pills, anticonvulsants, lithium, and steroids)

Most of the time, pimples that develop due to certain drugs aren’t truly acne at all but rather a type of rash that causes acne-like eruptions. If you’re taking any medication and develop acne or a rash, let your healthcare provider know right away.

Acne at Various Life Stages

While the teen years are the most common, and prime years for acne development, acne is common during other life stages because of hormonal shifts in the body.

  • Puberty
  • Pregnancy and immediately after delivery
  • Birth (in the case of newborn acne)
  • Perimenopause and menopause
  • Monthly just before your period (often called PMS acne)

Genetics

Acne does have a genetic component to it, as it does tend to run in families. There is not a specific gene that causes acne. Rather the factors that make acne more likely to develop are traits that can be passed down.

Myths

There is probably no other skin condition that is linked to so many myths, misunderstandings, and confusion about its causes and development than acne. These old wives’ tales seem to hang on, and stop many people from getting the appropriate treatment, or even seeking treatment in the first place.

If your parents or siblings had acne at any point in their lives, you are more likely to develop it at some point too.

These things do not cause acne:

  • Foods like chocolate, potato chips, pizza, or fried foodsNot washing your face enough, or being “dirty"Touching your faceMasturbation, having sex, or not having sex

Also, acne isn’t contagious, so you can’t catch it from someone else.

While diet doesn’t cause acne, there is a possible connection between certain foods and acne severity. More research needs to be done to prove a definitive link, but studies suggest that dairy products, as well as high-glycemic-index foods (i.e. refined carbs), may make existing acne worse.

A Word from Verywell

The most important thing to remember when you’re dealing with acne is this: it’s not your fault. Acne isn’t caused by what you did or didn’t do. Some people are just prone to developing breakouts.

But acne is treatable. If you’re not getting good results with over-the-counter acne products, there are plenty of prescription acne medications that may work for you. Give your healthcare provider a call to start the treatment process.

Frequently Asked Questions

  • What causes acne?
  • Acne is the result of four processes that lead to the blockage of hair follicles and the formation of pimples:Excessive production of an oily substance called sebumBuild-up of dead skin cells in hair folliclesInfection within hair follicles by bacteria called Cutibacterium acnesInflammation within the pores and surrounding skinGenetics may predispose certain people to acne, while hormonal changes are known to play a role in acne breakouts.
  • What hormone is responsible for acne?
  • Androgens (male hormones) appear to be the hormones most responsible for acne. This includes the hormones testosterone, dihydrotestosterone (DHT), and dehydroepiandrosterone (DHEA). High levels of insulin and growth hormone (GH) are also linked to worsening acne.
  • What causes acne in adults?
  • In women, hormonal fluctuations during the menstrual cycle play a key role in adult-onset acne, while stress, hormonal contraceptives, and smoking are considered risk factors. Some studies suggest that women are four times more likely to experience adult-onset acne than men.
  • What causes cystic acne?
  • It is not entirely clear why some people have cystic acne, but it is thought that a severe inflammatory response weakens the lining of sebaceous glands that produce sebum (oil). This can cause sebum, dead skin cells, and bacteria to seep into deeper tissues, causing infection and the formation of cysts and nodules.
  • What causes acne scars?
  • Acne scars are usually the result of a severe acne breakout, during which hair follicles can become clogged with sebum, bacteria, and dead skin cells. This can cause the follicle wall to rupture, leading to the formation of a scar. In some cases, the rupture can cause a raised scar called a hypertrophic scar, most typically on the torso.
  • Can certain foods contribute to acne?
  • Possibly. Diet can influence hormone levels, and some foods are known to cause inflammation that may make acne worse. Foods like milk and added sugar can increase insulin levels, which might also contribute. At present, there is no consensus as to whether a change of diet will necessarily improve acne.

Acne is the result of four processes that lead to the blockage of hair follicles and the formation of pimples:

Androgens (male hormones) appear to be the hormones most responsible for acne. This includes the hormones testosterone, dihydrotestosterone (DHT), and dehydroepiandrosterone (DHEA). High levels of insulin and growth hormone (GH) are also linked to worsening acne.

In women, hormonal fluctuations during the menstrual cycle play a key role in adult-onset acne, while stress, hormonal contraceptives, and smoking are considered risk factors. Some studies suggest that women are four times more likely to experience adult-onset acne than men.

It is not entirely clear why some people have cystic acne, but it is thought that a severe inflammatory response weakens the lining of sebaceous glands that produce sebum (oil). This can cause sebum, dead skin cells, and bacteria to seep into deeper tissues, causing infection and the formation of cysts and nodules.

Acne scars are usually the result of a severe acne breakout, during which hair follicles can become clogged with sebum, bacteria, and dead skin cells. This can cause the follicle wall to rupture, leading to the formation of a scar. In some cases, the rupture can cause a raised scar called a hypertrophic scar, most typically on the torso.

Possibly. Diet can influence hormone levels, and some foods are known to cause inflammation that may make acne worse. Foods like milk and added sugar can increase insulin levels, which might also contribute. At present, there is no consensus as to whether a change of diet will necessarily improve acne.