Seborrheic dermatitis (face or scalp): causes, symptoms and best treatments

 Dermatitis or seborrhoeic dermatitis is a common skin disease in babies and adults. It manifests itself in the form of chronic flare-ups sometimes accompanied by pruritus, mainly on the face and scalp.

1. What is seborrhoeic dermatitis?

Adult seborrhoeic dermatitis is a chronic inflammatory skin disease (or dermatosis) characterised by thick, white, sometimes yellowish, erythematous scaly patches. These lesions develop in the areas where sebum secretion is most important (known as "oily" or "seborrheic"), such as the scalp; the furrow between the nose and the cheeks, or lips; the eyebrows, and the space between them. But patches can also appear in the beard, or in the cleavage between the two breasts.

Its topography is suggestive and distinguishes it from other facial conditions, although it can sometimes resemble psoriasis when it is not very developed. It's not uncommon for someone with dermatitis to also have psoriasis," says Fischer, "as both diseases develop on the same skin type.

It is a benign and non-contagious disease, but it is chronic and incurable: it evolves through recurrent outbreaks. Outside of the flare-ups, the skin returns to its normal appearance, although it can sometimes remain slightly red. It is often sensitive to friction and irritants.

Because of the apparent nature of the lesions, seborrhoeic dermatitis has an impact on the quality of life. A Korean study of a sample of nearly 12,000 people found that adults with atopic dermatitis had a significantly lower quality of life and higher stress levels than those without the disease. 

Another study, conducted in 2006, has a suggestive title: "Quality of life and childhood atopic dermatitis: the hell of childhood eczema".

2. A common disease in adults, but also in babies

According to the French Health Insurance, seborrheic dermatitis affects 1 to 3% of French people between adolescence and adulthood, with a peak in frequency between the ages of 18 and 40. Six men are affected for every woman. After the age of 40, the disease is less common and almost exclusively affects men.

In babies, the so-called "cradle cap" is actually a mild form of seborrhoeic dermatitis. Starting after the second week of life, it results in thick, crusty, white, or yellow patches that may be surrounded by redness. These symptoms may also affect the buttocks or skin folds. The cradle cap" is not itchy and does not cause any discomfort to the infant. They are not contagious.

In immunocompromised people (HIV), suffering from Parkinson's disease or Down's syndrome, the disease can appear in a severe form. According to the Vidal, 80% of AIDS patients have extensive and atypical forms.

3. What are the symptoms of this skin disease?

During flare-ups of seborrhoeic dermatitis, erythematous scaly patches appear. They are darker at the edges and are covered with white or yellowish flakes of varying degrees of oiliness. These flakes are easily detached, leaving areas of light red skin.

These patches may cause itching or even burning sensations in some people. However, others may have no symptoms other than the patches.

• Seborrheic dermatitis patches on the scalp

Affected in 95% of cases, according to the Assurance Maladie, the scalp is sometimes the only part of the body affected. Seborrheic dermatitis patches form mainly near the temples and at the top of the head. They may then spread to the entire scalp and extend to the forehead, the base of the neck, and the back of the ears. These patches are usually hidden by the hair. However, they are covered with a lot of dandruff, which is very visible on the head and when it falls on clothes.

• Seborrheic dermatitis on the face

The face is often affected by seborrhoeic dermatitis, especially in the middle. The patches and flakes of skin form mainly in the grooves around the nostrils in the fold under the lower lip, in men on the beard and moustache, behind the ears, and in the external auditory canals (which may then ooze).

In severe disease, yellow and red scaling papules appear along the hairline, behind the ears, on the eyebrows, in the nasolabial folds, and on the breastbone. Marginal blepharitis (an inflammation of the eyelid margin) with dry yellowish crusts and conjunctival irritation may develop.

4. What are the causes and contributing factors?

The pathophysiology of dermatitis is still incomplete. However, it is likely that sebum production by the sebaceous glands is associated with it: increased sebum production naturally occurs at ages when the prevalence of the disease is higher; DS occurs precisely where there are more sebaceous glands.

However, seborrhoea is not always linked to the development of the disease, as some studies on acne have shown. Seborrhoea could therefore act as a factor favouring the development of dermatitis. However, the theory of increased sebum production does not by itself explain the mechanisms involved: some affected patients have a normal sebum production and people with an overproduction of sebum do not systematically develop the pathology.

The imbalance of the flora, and the abnormal proliferation of yeasts such as malassezia furfur (a type of fungus), which are naturally present on the skin, also play a role in the appearance of seborrhoeic dermatitis. These micro-organisms cause a specific inflammatory reaction, resulting in erythema (redness of the skin) and accelerated renewal of the scalp and skin cells in 5 to 14 days instead of the usual 28 days. This results in unusual scaling.

Alcoholism, stress, fatigue, overwork, emotional shock... can favour or even in some cases trigger the appearance of dermatitis, says the dermatologist. But other factors can also intervene:

• the cutaneous application of greasy substances (e.g.: sun oil) or alcohol-based lotions;
• inadequate personal hygiene;
• exposure to humidity and heat, or on the contrary, to very cold temperatures;
• hypersudation;
• obesity
• Pregnancy;
• taking certain medications such as neuroleptics;
• cancer of the upper aerodigestive tract.

The lesions fluctuate, and many sufferers stress the variability of the signs and the influence of their emotional state on the flare-ups, and also note the favourable effect of sunshine and holidays.

5. How does the dermatologist diagnose seborrhoeic dermatitis?

The diagnosis of seborrhoeic dermatitis is based on the clinical examination, it is not necessary to carry out a biopsy. However, if the dermatitis is in a severe, extensive form, it may be questioned as to the contributing factors and could lead the specialist to carry out further examinations if he or she suspects that another, more serious pathology is the cause.

Seborrheic dermatitis must then be differentiated from other pathologies such as:

• Atopic dermatitis: this disorder usually manifests itself first as a fine, white, dry scaling rather than the yellowish greasy scaling of seborrhoeic dermatitis.
• Psoriasis: the erythematous, scaly patches are clearly demarcated.
• Rosacea: when rosacea affects the face, it initially manifests as erythema, papules and papulopustules but not as scaling (however, patients may have both seborrhoeic dermatitis and rosacea)

6. How is dermatitis treated?

The treatments used are quite varied, which is probably related to the fact that the aetiology of the disease is multi-factorial and unclear at the moment. They will aim to reduce the malassezia furfur yeast while combating the inflammation and excessive sebum secretion. Whatever treatment is undertaken, it will never be curative: there will always be risks of relapses, more or less early and significant, depending on the treatments used.

A gentle, non-aggressive, moisturising and non-greasy product;

products that limit the progression of fungi (such as zinc gluconate);

Local antifungals ;

and dermocorticoids when very inflammatory but not for too long, as there can be a very significant rebound effect.

Flora Fischer specifies that certain products, such as a non-aggressive, non-greasy moisturising cream, must be used on a daily basis to avoid recurrences. It is a preventive treatment, easy to integrate into one's daily life.

In order to reduce the impact of stress, it can be interesting to combine soft therapies such as acupuncture or sophrology.

Sources :

Kwak Y, Kim Y. Health related quality of life and mental health of adults with atopic dermatitis. Arch Psychiatr Nurs. 2017 Oct;31(5):516-521. doi: 10.1016/j.apnu.2017.06.001. Epub 2017 Jun 2.