Acne: What is it & what causes it?

Acne - What exactly is acne & what causes it?

Acne is one of the most common skin diseases worldwide. Acne vulgaris is the technical term for “common acne”.

The chronic, inflammatory skin disease affects the sebaceous glands and the terminal hair follicles. Typical symptoms are pimples, blackheads (comedones), oily skin as well as papules and pustules. 1

Pimples and blackheads are caused by increased sebum production (seborrhea) and the keratinization disorder of the sebaceous follicles.

In this article you will learn everything you need to know about acne in general, the cause, possible risk factors and treatment.

Acne – an overview of interesting facts

  • In 70 to 95 percent of adolescents, acne appears between the ages of 15 and 18. Young men are more frequently and usually more severely affected than girls of the same age.
  • Acne comes in various forms:
    • Baby acne(acne neonatorum)
    • Infant acne, toddler acne (acne infantum)
    • Puberty acne (common acne, acne vulgaris)
    • Adult acne (acne tarda)
  • In 15 to 30 percent of patients, acne requires medical treatment or dermatologist therapy due to its severity.
  • The face and upper body are most frequently affected by blemishes such as spots and blackheads.
  • The change in hormone levels in adolescents during puberty is considered the most common cause of acne. This is why acne usually disappears by itself after puberty.

What is acne?

Acne is a skin disease that mainly occurs during puberty and then often disappears spontaneously. However, acne can occur at any age.

Externally, it is characterized by pimples, blackheads and pustules. In most cases, hormonal changes in the body are responsible for acne.

Acne vulgaris is the most common form and is called puberty acne. With the right measures, acne symptoms can be treated well.

Typical symptoms of acne

Blackheads (comedones), pimples (pus-filled blisters), small skin thickenings (papules), inflamed nodules and oily skin are among the typical symptoms of acne. These occur more frequently where there are many sebaceous glands.

Sebaceous glands are mainly located on the face (forehead, cheeks, chin and nose), on the back, on the back of the upper arms, on the chest (décolleté), on the neck and on the nape of the neck.

Preliminary stage of pimples and blackheads: inflammation

Small micro-inflammations under the skin are the beginning of pimples, blackheads and reddening of the skin. They are considered to be the main cause of acne and are not visible at first. As the acne progresses, the inflammatory reaction intensifies.

The body’s own immune system reacts to bacteria, lipids and androgens. This immune reaction becomes visible as pimples. If this remains closed, the surrounding tissue becomes inflamed and the typical reddening of the skin occurs.

Who is affected by acne?

Pimples and blackheads

Pimples are basically clogged pores where the excess sebum produced cannot drain away. They are usually noticeable in the form of redness. However, unlike blackheads, pimples lie under the top layer of skin.

This prevents them from coming into contact with oxygen. Pimples therefore usually cause painful swelling under the surface of the skin. Scars may remain after the swelling has subsided.

Blackheads are located very close to the surface of the skin and usually appear as small, black dots. Blackheads are caused by clogged pores. As they come into contact with oxygen, they are perceived in the form of the characteristic black dots.

Reddened skin due to blackheads

Skin redness is a visible inflammation caused by the growth of bacteria. Initially, sebaceous gland secretions accumulate in the skin and form the ideal breeding ground for bacteria. The bacterium Propionibacterium acnes in particular feels at home there.

This bacterium is found deep in the sebaceous glands and multiplies particularly well in blackheads. The bacteria break down the sebum and this produces free fatty acids, which trigger further inflammatory processes. These then ultimately lead to reddening of the skin.

Causes of acne

The causes of acne can be very different. Acne vulgaris is mainly triggered by hormonal changes. These hormonal fluctuations usually occur during puberty, pregnancy or the menopause.

Genetic predisposition and external influences (such as stress or medication) can also promote acne.

Acne - Causes of acne & types of acne

You can find out more about the triggers of acne in the article “Why do you have acne? The triggers of acne”

Hormonal causes of acne

Hormones can be a cause of acne. The hormones that trigger acne (androgens) are produced in the testicles and adrenal glands in men. In women, androgen hormone production takes place in the ovaries.

If there is an imbalance of hormones, the production of the body’s own sebum is increased.

Bacteria accumulate over time. Further blackheads and inflammation are the result. As a result, pimples, papules and other symptoms of acne develop due to a hormonal imbalance.

Stress as a trigger for acne

The skin is considered a mirror of the soul. You can easily see whether your body is in balance or not. During periods of intense stress, the body releases more hormones such as cortisol and adrenaline. This hormonal imbalance can cause typical acne symptoms such as pimples, blackheads and redness.

In stressful situations, typical and usually unhealthy lifestyle habits are part of this. These can also have an unfavorable effect on the skin.


Acne can be triggered or aggravated by medication. For example, pimples and pustules are caused by cortisone preparations, vitamin B complex, iodine compounds, antidepressants or modern anti-tumor preparations.

Other risk factors for acne

In addition to hormonal causes, genetic predisposition, stress and medication as causes, there are other risk factors that can promote acne.

These factors can be

The different types of acne

Acne can be divided into endogenous acne and exogenous acne. Endogenous forms are always caused by the body’s own factors, usually hormonal changes.

Exogenous forms are caused by external factors. Endogenous forms of acne are divided into different age phases.

Types of acne according to age

Baby acne – Acne neonatorum

Baby acne, also known as neonatal acne, affects babies in the neonatal period. This begins at birth and lasts until the child is four weeks old.

Baby acne - Acne neonatorum

Baby acne can be present from birth or develop in the first few weeks of life. Visually, it hardly differs from acne in adolescents. A rash with fine, reddish pustules and mostly closed comedones develops.

The causes of baby acne are:

Infant acne & toddler acne – Acne infantum

Infant acne occurs in pre-pubertal childhood. It is also called infant acne. This form of acne mainly affects male infants aged three to six months. The causes of infant acne are not fully understood medically.

Possible triggers can be

Puberty acne – acne vulgaris

Acne vulgaris is hormonal. The male sex hormones (androgens) are mainly responsible for the skin disease. The main representative of the male sex hormones is testosterone.

This hormone is increasingly produced in men, especially during puberty. Women are also affected to a lesser extent.

Typical symptoms of acne

However, it is mostly male adolescents who suffer from acne vulgaris, as their testosterone levels rise rapidly during puberty. This upsets the hormonal balance.

At the same time, the production of horny material in the skin increases during puberty. This combination leads to clogging of the pores.

Acne vulgaris usually disappears of its own accord by the age of twenty-five. By the early thirties at the latest.

Adult acne – Acne tarda

Acne in adults is called acne tarda or late acne. Like acne vulgaris, it is a hormone-induced acne. In adult women, hormonal changes can be due to various factors.

For example, menstruation, pregnancy or stopping the contraceptive pill can have an impact on a woman’s hormone balance.

Late acne is almost always caused by a change in the ratio of male and female sex hormones. Acne tarda occurs more frequently in women than in men. However, the course of the disease is more severe in men.

In addition to hormonal imbalance, diet, a disturbed intestinal flora, stress or excessive skin care can play a role in adult acne.

Acne forms according to severity

Furthermore, three different degrees of severity can be identified. This classification is always based on “common” acne vulgaris:

Special forms of acne

There are also a number of other forms of acne in which external factors usually play a role:

These special forms of acne have no hormonal or genetic causes. To make it easier to understand, we will illustrate it using the example of “acne cosmetica”.

Acne cosmetica” refers to the fact that certain cosmetic products promote the development of acne. The skin of those affected is basically healthy and the skin disease is caused by the unfavorable ingredients of the cosmetics.

Acne diagnosis

Early diagnosis and targeted treatment can help to control the course of the disease. Severe courses with scarring and complications can be largely prevented.

Acne can be diagnosed by the following examinations:

The treatment options for acne

The acne treatment always depends on the form of acne and its progression or severity. The options range from externally and locally applied ointments to treatment with medication and light therapy.

Acne treatment options

Mild acne is initially treated with creams containing retinoids , but some home remedies can also provide relief. Another method is to use bacteriophages to reduce the “bad” bacteria, such as Propionibacterium acnes. By restoring the balance of the human microbiome, the skin improves. 2

In severe cases of acne, a doctor or dermatologist should be involved in the treatment. Treatment with antibiotics may be used. Alternatives should be tried beforehand. The most important thing in treatment is to start early and stick with it consistently. This significantly reduces the risk of scarring.

More about acne

  1. 1.
    Degitz K, Placzek M, Borelli C, Plewig G. Pathophysiology of acne. J Dtsch Dermatol Ges. 2007;5(4):316-323. doi:10.1111/j.1610-0387.2007.06274.x
  2. 2.
    Marinelli LJ, Fitz-Gibbon S, Hayes C, et al. Propionibacterium acnes Bacteriophages Display Limited Genetic Diversity and Broad Killing Activity against Bacterial Skin Isolates. Davies JE, ed. mBio. Published online September 25, 2012. doi:10.1128/mbio.00279-12
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