What is acne?

An inflammatory disorder of the sebaceous glands, acne is characterised by the appearance of comedones and red or white pimples on the chest, back and especially the face. Hormonal disturbances are the cause of this disorder that affects most teenagers, but also many adult women.

Submitted on 20/07/2012


A disorder of the sebaceous glands

Every pore of our skin contains a hair and a sebaceous gland. Normally, the latter secretes sebum, an oily substance that helps to protect the skin from dehydration and external harm by a thin lipidic film.

But in the event of an increase in testosterone in the body (as is the case at puberty in boys and girls) or hypersensitivity to this hormone, the production of sebum becomes excessive, the sebaceous glands become hypertrophied and the pores become enlarged: this is known as hyperseborrhoea.

Secreted in excess, the sebum also changes in character: more concentrated in squalene and wax, it becomes irritant, comedogenic and pro-inflammatory. This modified sebum spreads over the skin which becomes oily and shiny, especially in areas rich in sebaceous glands: the nose, forehead, chin, but also the chest, upper back and arms. Invisible inflammation is then already at work.

The formation of comedones

In parallel to this, the renewal process of skin cells is disturbed. Dead cells accumulate in the follicular canal connecting the sebaceous gland to the skin, which gradually becomes clogged: this is hyperkeratinisation. Thus trapped, the sebum builds up and forms a plug which shows up in the form of an irregular and whitish lump on the skin known as a closed comedone, microcyst or, more commonly, a whitehead.

From whitehead to blackhead

Sometimes this comedone regresses naturally. But generally, it continues to develop: its volume causes an accumulation of dead skin cells that clog the pore and are in contact with air where the sebum oxidises and turns black. The result is a blackhead or open comedone. Whiteheads and blackheads make up what is known as "comedonal" acne.

When pimples appear

Over time the hyperseborrhoea promotes the multiplication of the bacterium, Proponibacterium acnes, which finds itself in an oily and oxygen-free environment, ideal conditions for its proliferation. The comedone becomes inflamed and fills with pus. The surrounding tissues become infected and swell, then becoming red and painful. You then see a red pimple (papule) or white pimple (pustule or nodule) and this is known as "inflammatory" acne. In more than fifty percent of cases, acne-prone skin has both inflammatory and comedonal lesions.

The evolution of acne

If you do not touch them, the inflamed pimples regress spontaneously within a few days. Conversely, if you squeeze them you risk bursting the sebaceous gland and spreading the pus and bacteria more widely on the epidermis and within the dermis, thus multiplying the acne lesions and making them worse as well as increasing the risk of scarring.

Acne evolves in flare-ups, which means that periods of growth of lesions alternate with periods of improvement in the condition of the skin. It generally disappears spontaneously at around the age of 20 years. However, it can persist into adulthood, especially among women: more than 40% of them still suffer from it after the age of 25 years. In that case, hormonal disorders are often involved.

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