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There are several factors behind the development of acne.

Acne usually develops in young teenagers at the onset of puberty, appearing on the face and even the back.

Hormones stimulate sebaceous glands, which produce an excess of sebum. As a result, the skin becomes oily and shiny and a variety of unsightly features emerge, sometimes inflamed.

Adults (especially women) can also be affected when undergoing hormonal changes (premenstrual syndrome, pregnancy, etc.) or stress, promoting hyperseborrhoea and bacterial proliferation.

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Acne occurs as a result of :

• Excessive sebum secretion.
• Proliferation of keratinocytes (skin cells). The pores on certain sebaceous glands become clogged. Sebum is unable to flow to the surface of the skin and forms microcysts or blackheads.
• Proliferation of the bacterium acnes, which adheres more easily when the horny layer becomes thicker.
• An inflammatory reaction (natural skin defense).

Microcysts, or closed comedons

These “whiteheads”, which may go unnoticed, are caused by an accumulation of sebum, the bacterium P. acnes and keratin. Microcysts can develop into open comedones. They can also become inflamed and become papules or pustules.

Open comedons

These features are known as “blackheads”. Comedones can empty spontaneously. They rarely become a focus of inflammation unless excessively touched.

Papules

These inflamed red spots, with a size under 5 mm, are painful. They can disappear or develop into pustules.

Pustules

These purulent yellow spots can empty and disappear, but they often return

Nodules

Nodules are seen in the most serious cases of acne. They are deep inflammatory lesions which can be felt through the skin. They can evolve and leave scars.