Understanding how to treat acne also go with understanding where acne comes from

Sebum, pores, comedones, hormonal acne, inflammatory acne… We hear the names without necessarily knowing what mechanisms produce blemishes and blackheads. Here’s a focus on how acne develops.

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    Dr Eglė Aukštuolienė, Centre for Dermatology and Venereology - Vilnius University Hospital’s Santara Clinic (Lithuania).

    95% of adolescents suffer from teenage acne.

    Puberty arrives earlier than it used to, and acne therefore also appears earlier among youth. Acne is found mostly on the face, and it can be difficult to hide all the blemishes. The condition can have a psychological impact and lead to a loss of self-confidence.


    Dr Eglė Aukštuolienė, Centre for Dermatology and Venereology - Vilnius University Hospital’s Santara Clinic (Lithuania).


To understand how pimples form, we need to start by looking at sebum and pilosebaceous follicles. This is the name for the small glands that produce sebum and are located under the epidermis. Present on most parts of the body, they’re found in large numbers on the face, scalp, and upper chest and back. This leads to the obvious conclusion that these are the areas where there is the highest amount of sebum. Each sebaceous gland is attached to a hair follicle, which is why it’s referred to as ‘pilosebaceous’, ‘pilo-‘ from the Latin ‘pilus’, meaning ‘hair’.

When everything goes well, pilosebaceous glands produce sebum that is fluid, normal in quality and in quantity. It is secreted by pores to hydrate and protect the skin. The ideal situation…


1. Sebaceous glands go overboard and produce too much sebum, which is too thick.

Specialists refer to this as hyperseborrhea (too much sebum) and dysseborrhea (poor quality sebum). The sebum that produces acne has a different composition compared to healthy sebum. It’s missing vitamin E and oxidises easily.


2. Skin thickens. Dermatologists call it hyperkeratinisation.

Skin sloughs off less and thickens, which ends up plugging pores that usually take care of evacuating sebum. A keratolytic treatment will soften skin, helping to reduce the epidermis and make skin thin again.


3. Pores can’t secrete sebum properly. It stays blocked under the skin.

At this point, an open comedo develops, more commonly known as a blackhead. The black colour is because the sebum is oxidised by the air.


4. Bacteria develop in the pilosebaceous follicle.

The accumulated sebum is the ideal place for the bacteria responsible for acne, Cutibacterium acnes, to develop. The inflammatory stage has been reached, where a closed comedo forms – a painful red spot.


In France, one out of every four people between 20 and 40 years of age state that they have acne*. Acne is mostly a problem during adolescence since it’s the moment when the hormonal system becomes active and sebum production begins.

And yet, not all teenagers are affected in the same way, and many no longer have acne after 25 years of age. But in some cases, blemishes stay put long after puberty has finished. Acne can also start during adulthood, return after a calmer period of a few years, and during pregnancy. It’s hard to say at what age acne disappears!


There are three reasons for having acne:

  • Hereditary: If parents had acne, there is a greater risk of their children having it.
  • An increased sensitivity to male hormones (even among girls), more than an actual hormonal imbalance, which remains extremely rare. Hormones influence both sebum production, or hyperseborrhea, and hyperkeratinisation, when the skin thickens.
  • The environment in the broadest terms, since a link, has been established between stress and acne, smoking and acne, diet and acne, acne and pollution or wearing a mask for long periods of time – without forgetting exposure to endocrine disruptors and poorly chosen cosmetic products.


*Arcane Research Study France – February 2017



The five stages of acne and recommended treatments

The European Academy of Dermatology and Venereology has defined a specific plan of attack according to symptoms and acne’s severity, the Global Evaluation Acne (GEA). Here are the different stages of acne and the recommended treatments.

Acne level 1

Very light acne – Stage 1 GEA

A few comedones, blackheads and whiteheads, and rare red blemishes that are spread out. The Academy recommends local treatments, generally retinoids or benzoyl peroxide. If after three months results are poor, the two treatments can be combined.

Acne level 2

Light acne – Stage 2 GEA

Less than half of the face has comedones (blackheads and whiteheads), and there are some red blemishes. Doctors often prescribe a combination of retinoids and benzoyl peroxide for local application. If after three months the acne persists, a local antibiotic treatment can be added, before moving on to an oral antibiotic treatment from the cycline family. Erythromycine is not very effective and bacteria are highly resistant to this type of molecule, which must be used only for very specific cases.

Acne level 3

Moderate to severe acne – Stages 3 and 4 GEA

Over half of the face is covered – all of the face at stage 4. Blemishes can be found on the nose, forehead, chin, sometimes on the back, and include comedones (blackheads and whiteheads), numerous red spots, some cysts and nodules. If the therapeutic strategies mentioned previously didn’t work, isotretinoin taken orally can be considered, especially if there’s a high risk of scarring.

Acne level 5

Very severe acne – Stage 5 GEA

The whole face is covered with multiple cysts and nodules. Oral isotretinoin is prescribed, especially if there is inflammation. Eliminating comedonal lesions by microsurgery is recommended before starting treatment, to avoid periods of inflammation, which are normal during the first weeks...

Here are a few terms to be clear about the vocabulary for acne, to help understand how to treat acne-prone skin

The acne that sprouts during adolescence, as opposed to persistent adult acne.

This term isn’t just for referring to 30-something acne or severe adult acne, as is often believed. By definition, acne is influenced by hormones, whatever a person’s age or sex. Hormonal acne is more often experienced by women, who undergo numerous hormonal changes due to their menstrual cycle, pregnancy and menopause.

Recognisable thanks to shiny skin from excess sebum, very visible pores that are widely dilated, and raised blackheads and whiteheads under the skin. This is often the first stage of acne (very light acne), which requires a hyperseborrhea treatment.

Stage 2 acne (light acne) is when bacteria have multiplied, producing large red blemishes that are raised and often painful. Based on how they evolve, they’re referred to as papules, pustules and nodules.

This corresponds to stage 3 acne (moderate acne), when red blemishes have turned into deep, painful cysts that are often hard since they are enclosed within a sort of shell which makes them impossible to remove, except by a dermatologist. Don’t touch severe facial acne. The risk of scarring is high!

These are two severe and rare forms of acne, that affect mostly men between the ages of 18 and 30 years old. They require consulting a dermatologist.

The scientific name for certain types of acne blemishes. Open comedones are blackheads, and closed comedones are whiteheads or red blemishes.

A different type of closed comedo. Microcysts are raised blemishes under the skin, topped by a white cap. They can become red and drain off, or sometimes be resorbed.

Also called nodules in dermatology, cysts are located deep under the skin. Hard and painful, they can last months and evolve during flare-ups.

A raised, red blemish that shows the start of inflammation due to an increase in Cutibacterium acnes bacteria. It’s the beginning of a pimple’s lifecycle.

A raised, red blemish with a white cap, when a papule has become worse.


Hygiene & skincare

Combination, oily to acne-prone skin

The Sébium range


The skin changes during adolescence: it becomes thicker, shiny, blemishes appear to a varying extent and sometimes remain into adulthood.

Bioderma’s solution: Sébium, a range tailored for oily, combination and acne-prone skin. 
The Sébium range has cleansing and care products that are specifically recommended by dermatologists: face cleansers for oily skin (foaming gel and micellar water), anti-blemish creams, moisturisers for acne-prone skin, and more. Choose your routine!