Seborrheic dermatitis: symptoms and causes

What is seborrheic dermatitis?

Also known as seborrheic eczema, seborrheic dermatitis is a chronic inflammatory skin disease, non-contagious, essentially affecting areas rich in sebaceous glands: scalp, eyebrows, sides of the nose, nasolabial folds, beard, external ear canal, upper trunk.

It is characterized by the association of redness and scaling (dandruff on the hair and face), often greasy, and of varying intensity depending on the period. Its evolution occurs in flare-ups, interspersed with phases of calm [1].

Seborrheic dermatitis (not to be confused with atopic dermatitis) is not a serious condition, but it can impair quality of life due to its visible, uncomfortable, and recurring nature.

What are the symptoms of seborrheic dermatitis?

Seborrheic dermatitis can present several manifestations, varying according to the affected area and age.

Symptoms in adults:

Scalp and hair:

Scalp involvement is the most frequent (95%) [2]. Symptoms can begin in a localized area and spread over the entire scalp [1], as well as to the beard.

• Scales that can lead to the formation of greasy yellowish or whitish dandruff.

• Crusts adhering to the scalp. Their yellow appearance indicates a more significant inflammatory state than dandruff.

• Diffuse redness.

• Itching (pruritus) that is more or less uncomfortable.

Face:

Seborrheic dermatitis primarily appears on the T-zone (sides of the nose, eyebrows, forehead, eyelids), which is particularly rich in sebaceous glands, with:

• Red erythematous plaques of varying extent

• Fine, sometimes greasy scales.

Symptoms in infants:

Seborrheic dermatitis is often associated with "cradle cap." Primarily located on the child's scalp, it less commonly affects the face.

It appears in the first weeks of life with thick, yellowish, and greasy scales.

It is a benign and painless condition, with no impact on the child's health, and usually resolves spontaneously during the first year of life.

What are the causes of seborrheic dermatitis?

In both adults and infants, seborrheic dermatitis results from a combination of biological factors:

• An excessive secretion of sebum by the sebaceous glands.

• The proliferation of a yeast naturally present on the skin: Malassezia.

• An inappropriate inflammatory reaction of the skin to this yeast.

• A weakened barrier function.

In newborns, the influence of maternal hormones is added to these factors.

Other factors can promote or aggravate seborrheic dermatitis flare-ups:

• Stress and fatigue.

• Hormonal changes.

• Certain climatic conditions (cold, humidity).

• Products unsuitable for the scalp.

It is important to emphasize that seborrheic dermatitis is not related to poor hygiene.

Who is most often affected?

The diagnosis of seborrheic dermatitis can vary depending on its symptoms. Thus, while it is estimated to affect 2 to 5% of the population, according to diagnostic criteria, it could affect nearly 10% of the population [3].

It can appear in different profiles such as:

• Infants, in the first weeks of life.

• Adolescents and young adults.

• Adults with oily skin.

• Adults prone to stress, fatigue.

In adults, seborrheic dermatitis affects both men and women, with a slightly higher proportion in men, due to their higher density of sebaceous glands.

In adults, seborrheic dermatitis is a frequent, inflammatory, and chronic condition, which requires a deep understanding of its mechanisms to better manage it daily.

Dermocosmetic solutions developed by Laboratoire Dermatologique ACM, particularly within the Novophane range dedicated to hair and scalp health, are part of this global approach by helping to soothe discomfort, reduce the appearance of scales, and provide long-term support for skin prone to recurrence, in addition to medical advice if necessary.

How long does seborrheic dermatitis last?

Seborrheic dermatitis is a chronic condition, manifesting in phases of flare-ups and remission. Symptoms can last from a few weeks to several months, then reappear. Adapted management helps to space out recurrences and improve daily skin comfort.

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