Definition: what is seborrheic dermatitis?
The seborrheic dermatitis is a skin disease which manifests itself by Red plaques surmounted by yellowish white scales : “This inflammatory dermatosis is particularly troublesome and it is often the cause of complexes in young adults who are most affected by this condition”, underlines Doctor Marie Estelle Roux, liberal dermatologist in Paris.
This is because seborrheic dermatitis is usually visible because it appears in areas such as the T zone of the face and the bust. “It is also apparent when it manifests itself on the scalp causing clumps of dandruff at the roots of the hair, ”adds the specialist.
The areas of the body affected are those which reject a lot of sebum and where a fungus that causes the disease proliferates: Malassezia.
“The main risk factor is oily or sebborheic skin. Other hypothetical factors come into play, such as a genetic predisposition, ”explains the practitioner.
Treatment relieves symptoms and allows remission, but this condition can come back.
A very common condition
“Seborrheic dermatitis is very common and I see it regularly in consultation. If you pay attention, you will see that a lot of people have this type of lesion ”, according to Marie Estelle Roux. In fact, seborrheic dermatitis affects between 1 and 3% of French people (source 1). The young adults men (18-40 years old) are particularly at risk (source 1).
What are the causes) ?
The development of seborrheic dermatitis is associated with the overgrowth of a Malessezia furfur fungus. The presence of this yeast on the skin flora is not pathological, however work shows that the proportion of Malessezia is abnormally high in people with seborrheic dermatitis (source 2).
For some scientists, this fungal hyperproliferation is sufficient to explain the symptoms of seborrheic dermatitis. For others, the disease is the result of immune response disproportionate to this fungus (source 3). Finally, studies suggest that these fungi have a gene encoding a digestive enzyme allowing the transformation of triglycerides in sebum into free fatty acids at the origin of an inflammatory reaction (source 4).
What are the risk factors for this skin disease?
The seborrheic dermatitis is associated with certain risk factors:
Age : the disease preferentially affects individuals from 18 to 40 years old. The disease becomes rare after 40 years (source 1);
- Gender : men are mainly affected because they produce more sebum;
- A oily or seborrheic skin ;
- Excessive sweating ;
- From associated diseases with seborrheic dermatitis: – The HIV : seborrheic dermatitis is frequently observed at the time of diagnosis of the disease and most of the time disappears as soon as anti-retroviral treatments are started (source 5). – The Parkinson disease : the decrease in dopamine would lead to a deregulation of sebum production and a modification of its composition.
- Psychiatric illnesses are also sometimes associated with seborrheic dermatitis.
- Chronic stress or anxiety ;
- Alcoholism ;
Certain events or behaviors can also worsen or favor the onset of the disease:
- Lack of hygiene (especially of the face and scalp);
- The application of lotions or oily creams on the skin or scalp;
- A bad lifestyle and more particularly an unbalanced and too fatty diet (source 5);
- An episode of intense stress or fatigue ;
- Climatic factors: cold, humidity, high heat…;
- Excessive consumption ofalcohol and tobacco ;
- Obesity .
What are the symptoms of seborrheic dermatitis?
Appearance of lesions
An episode of seborrheic dermatitis usually lasts Several weeks (or even several months in the event of poor or no support). It is characterized by the appearance of lesions on the areas where we produce the most sebum. The rash includes:
- from scaly red patches whose surface is one whitish or yellowish color close to that of pus;
- skin particles come off the plates;
- usually the patient complains of a pruritus and a pain at the lesions.
The areas of the body affected are usually:
- the scalp is most often affected by the disease. The patient presents clumps of dandruff at the hairline as well as moderate itching in the skull;
- thea T zone of the face, the eyebrows, the eyelids, the wings of the nose, the eyelids, the external auditory canal of the ears;
- the intermammary area.
Prevention tip (s)
In order to avoid a first attack or a relapse of seborrheic dermatitis, it is recommended:
- adopt careful personal hygiene by using products which respect the mucocutaneous flora;
- moisturize your skin with non-greasy substances ;
- wash your hair 2-3 times a week with a mild shampoo ;
- adopt a balanced diet;
- avoid the consumption of alcohol and tobacco;
- treat chronic stress or anxiety disorder.
- to perform zinc cures : this trace element would be effective against seborrheic dermatitis (source 6).
In case of seborrheic dermatitis attack and in order to avoid any aggravation, it is advisable to apply the personal hygiene instructions of your dermatologist or your general practitioner.
Diagnotic: how do you know if you have seborrheic dermatitis?
In case of suggestive symptoms, it is recommended to consult your general practitioner or a dermatologist. The latter will be able to make a diagnosis by simply physical examination. Indeed, additional examinations such as a skin sample or a blood test are not necessary except in cases of extensive seborrheic dermatitis. In this case an HIV test may be prescribed.
How to treat this skin disease?
The tseborrheic dermatitis treatments to relieve symptoms but do not provide no full recovery.
“After a first episode, the risk of relapse remains. It is therefore recommended to adopt preventive hygiene measures in order to avoid these recurrences. These precautions are also essential during treatment, ”according to Dr. Marie Estelle Roux.
The topical treatments (local application) are prescribed as a first-line treatment. In resistant or more severe cases, oral treatments can be considered. The treatment targets three objectives: reduce the number of Malassezia yeasts (through the effect of antifungals), fight against inflammation (by taking topical corticosteroids) and fight against the excessive production of sebum (or seborrhea).
The doctor can prescribe:
- from imidazoles (ketoconazole, bifonazole, sertaconazole) in the form of a foaming gel or cream;
- of the ciclopiroxolamine (pyridone) in cream or shampoo;
- from selenium sulfide : There is only one drug in France based on selenium sulphide: Selsun® 2.5% in solution for skin application. It is indicated in the management of Seborrheic dermatitis of the scalp.
Two applications per week are recommended at the start of treatment. Then the frequency of applications decreases.
They are used for short periods of time and in conjunction with topical antifungals. Indeed, if they act effectively on the symptoms, they expose the patient to relapses and “rebound effects”. In addition, these drugs have many undesirable effects on the skin (atrophy, depigmentation, acne rash, etc.), in the event of prolonged use.
- Hydrocortisone kerapharm cream 1% (class 4 topical corticosteroid) can be used to treat seborrheic dermatitis of the face;
- The Desonid (Class 3 topical corticosteroid) cream (Locapred or Tridesonid) can also be used for seborrheic dermatitis of the face;
- Class 2 topical corticosteroids (such as betamethasone ) cream, ointment or lotion, are intended for seborrheic dermatitis of the trunk or scalp. They should not be used on the face.
- Clobetasol (Class 1 topical corticosteroid) foam or gel can treat seborrheic dermatitis of the scalp.
Lithium-based creams are effective. They are softer and more respectful of the skin flora.
They complement the treatment of seborrheic dermatitis and are usually recommended by the doctor even when the disease does not affect the scalp (but other parts of the body or face). They are based on zinc pyrithione, of piroctone olamine, of selenium sulfide orsalicyclic acid.
In severe cases or resistance to local treatment, the doctor may prescribe retinoids at low dosages. They are very effective and their side effects, once criticized, are more and more controlled.