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Why do you have acne?

Understand what is happening to your skin during a breakout

Everyone is familiar with acne and the accompanying pimples, blackheads and other papules that always seem to show up at the wrong time. But why do some people have acne and not others? 
Acne is an inflammatory skin condition affecting the pilo-sebaceous follicles, which anchor each hair into the skin. Pilo-sebaceous follicles can be found across the entire surface of the body, except for the palms of the hands and the soles of the feet – on which pimples never form. 
As its name suggests, a pilo-sebaceous follicle consists of a hair and a sebaceous gland, which secretes sebum. Acne is the result of 4 main phenomena that will affect these follicles: hyperseborrhoea, dysseborrhoea, hyper-keratinisation and bacterial proliferation.

Hyperseborrhoea, or the first step leading to acne

Sebum is a complex mixture of lipids synthesised under hormonal stimulation by sebaceous glands in the dermis. Among other things, sebum helps hydrate your skin and delivers lipophilic antioxidants (lipophilic = with affinity for fats) onto its surface.
But for some of us, the skin will produce too much sebum, a phenomenon called Hyperseborrhoea. This results in the obstruction of the sebaceaous glands that will become inflamed and therefore provoke the apparition of pimples.
Several factors can lead to excessive production of sebum.
Here are the most common:
Hyperseborrhoea, or the first step leading to acne
Hyperseborrhoea, or the first step leading to acne
Influence of hormones
Sebaceous gland activity is regulated by hormones: it is reduced by oestrogens and increased by androgens. An abnormally high level of androgens, for example during menstruation, can cause sebum secretion to increase in women.
Location on the body
Pimples usually occur on areas where sebum is abundant: these include the scalp, face, neck, shoulders, chest area, upper back and thoracic region. On the face, sebum production is highest on the T-zone and the cheeks; it is lower on the upper eyelids and neck.
Under the influence of the mother’s hormones, the sebaceous glands become active in the first month of life. Their activity decreases after that until puberty, when there is a sharp increase in the secretion that lasts until adulthood. Sebum secretion slowly decreases in men after the age of 50; it drops most dramatically in women after the menopause.
Seasons and climate
A 1°C increase in cutaneous temperature leads to a 10% increase in sebum secretion, which is, therefore, higher in spring and summer.
Time of day
Sebum secretion is highest between noon and 2 pm.

Dysseborrhoea, or having a poor quality of sebum

Excess sebum was long considered to be the main cause of acne, but it is only partly responsible for our skin blemishes. Oily skin does not necessarily mean pimples and blackheads! In fact, we recently discovered that the real culprit in acne lesions is a change in sebum composition due to a lack of vitamin E. 
This change is called dysseborrhoea. Recently, researchers discovered a qualitative abnormality in the sebum of acne patients compared to healthy sebum. The sebum of people with acne lacks vitamin E, thus promoting skin-lipid oxidation. Since it becomes more difficult for sebum to flow outside of the follicle, it blocks the hair duct, and increase the risk of comedones.
Dysseborrhoea, or having a poor quality of sebum
Hyper-keratinisation, or thickening of the skin

Hyper-keratinisation, or thickening of the skin

Hyper-keratinisation refers to the excessive multiplication of skin cells in the follicle duct wall, causing a plug and thus keeping sebum from being evacuated properly. 
The result is the formation of comedones, i.e. small bumps on the skin. These may be skin-coloured (closed comedones, whiteheads or microcysts), causing the skin to appear grainy, or else have a black centre (open comedones), due either to the oxidation of lipids exposed to air or to the presence of melanin (a skin pigment) on the comedo’s surface. Comedones may be black in colour due to the oxidation of lipids exposed to air. This stage corresponds to comedonal acne.

Bacterial proliferation, or the spread of microbes

Sebum is an ideal nutrient medium for certain bacteria, especially Cutibacterium acnes, more recently called Propionibacterium acnes. 
Everyone has these bacteria on their skin. But the formation of a plug results in an ideal low-oxygen environment for these bacteria, which are then able to develop and proliferate in the pilo-sebaceous follicle. 
The body defends itself through an inflammatory response. The comedo then turns into a painful red spot called a papule, sometimes topped with a pustule that contains a yellow fluid. This progression is, therefore, the cause of inflammatory acne.
Bacterial proliferation, or the spread of microbes

You may also wonder about acne-prone skin…

Is acne necessarily related to oily skin?

Oily skin and acne always seem to be related: there can be no pimples without excess sebum. But contrary to popular belief, acne-prone skin is also easily weakened. 
The reason for this is simple: acne-prone skin is naturally dehydrated. This biological reality is too often forgotten in the fight against blemishes. 
The dysseborrhoea characteristic of acne often weakens the skin barrier, and the skin becomes dehydrated, particularly in severe acne. In this case, there is a double penalty of sensitivity + pimples with a very particular profile. This biological process by which acne-prone skin is weakened is exacerbated by certain types of acne treatments. 

Is acne hereditary?

It is commonly believed that acne has a genetic component and that there is a familial predisposition. Sociological studies seem to confirm this idea, with an increased likelihood of inheriting acne from the mother for young girls under the age of 20 and for women aged 25 to 40 who have acne*. 
Even though 46%* of adolescents between the ages of 12 and 19 confirm a family history of acne, there is currently no scientifically established genetic link.
*Arcane Research – February 2017

Why are teenagers more prone to acne?

This is the excess production of sebum resulting from hormonal activity triggered during puberty. The skin secretes very little sebum during childhood. The sebaceous glands become more active during puberty, when male sex hormones (androgens) start working, in girls as well as in boys. In most cases, excess sebum is then observed until the hormonal balance is restored. The skin becomes oily and shiny, but this hyperseborrhoea alone cannot explain why acne occurs: some people have oily skin but no pimples!


What is the link between acne and skin sensitivity?

We know that dysseborrhoea plays a significant role in the formation of blemishes. However, it is also responsible for the dehydration of acne-prone skin. 
Indeed, oxidation of the skin’s lipids modifies its structure and leaves it more permeable. The altered sebum composition of acne patients causes transepidermal water loss (TEWL) to increase, which is why acne-prone skin can be naturally dehydrated
The skin becomes sensitive and has a hard time tolerating topical and systemic acne treatments. Typical signs of dry and sensitive skin then appear, including redness, irritation, scales and itching.

Our best advice to take care of your acne-prone skin


Use Sébium Gel Moussant to purifies your skin and avoid the proliferation of bacteria thanks to the presence of copper, an anti-bacterial.


Use Sébium Global to regulate sebum quality (dysseborrhoea) and quantity (Hyperseborrhoea ).