Seborrheic dermatitis is a common chronic condition of the skin causes formation of white to yellowish scales and flakes oily areas such as the scalp or inside the ear. It can affect any age group but is most common in young adults with a peak around the age of 40. According to estimates about 1 in 25 adults is affected by seborrheic dermatitis. The condition affects more men than women.
Although the exact cause of seborrhoeic dermatitis is notknown, but some experts believe that a fungal germ called Malassezia furfur (previously called Pityrosporum ovale) and over production of skin oil may be involved. However, it is not a type of infection and it is not contagious, i.e. it is not transmitted from one person to other.
The germ is found in the sebum of human skin in most adults where it lives without causing harm in most people. But for reasons not known some people may react to this yeast germ which leads to skin inflammation and formation of white to yellowish scales and flakes and other symptoms.
The risk of developing seborrheic dermatitis is higher in people with immune system problems, such as HIV/AIDS and people with Parkinson's disease. These people are more likely to have more severe symptoms.
Some factors which increase the risk of seborrheic dermatitis are listed below.
- Family history: it is more common in people who have other members of the family affected by seborrheic dermatitis.
- Stress and fatigue.
- Extremes of climate (more common in colder seasons),
- Oily skin type.
- Infrequent shampoos or skin cleaning.
- Use of lotions that contain alcohol.
- Certain skin disorders such as acne.
Seborrheic dermatitis most commonly causes formation of scales and flakes (white to yellowish) on scalp. But it can affect other oily areas such as the eyebrows, eyelids, creases of the nose, lips, behind the ears, in the outer ear, and middle of the chest. Symptoms of seborrheic dermatitis can vary from mild to severe.
Mild cases: These with mild seborrheic dermatitis usually have bad dandruff on scalp. Dandruff is caused because of scaling of the scalp in seborrhoeic dermatitis. The scales form flakes and are seen on the scalp and fall on shoulders of dark clothing—this is often the first symptom of dandruff. There may be itch on the scalp as well. Some people may have mild patches of flaky skin on the face.
Moderate symptoms: These people develop rash. Rash of seborrheic dermatitis appears as round or oval patches of red, scaly, greasy skin which are usually a few centimetres in size. However the size of patches can vary. The rashes may be present in scalp, ear canal, eye lids etc. There may be yellow-brown crusts on the top of each patch. These rashes can itch and are slightly raised above the skin. The rashes on scalp may itch and become sore.
Severe symptoms: They are more common in people with some other medical condition such as weak immune system as in HIV/AIDS or Parkinson's disease. These people may develop extensive rash on face, scalp, neck, armpits, chest and groins.
Seborrheic dermatitis is usually a chronic condition and there is usually no permanent cure for it. Treatment improves the symptoms but in many people the symptoms recur after some time. In most people treatment with over- the-counter medicated shampoos improve symptoms of seborrheic dermatitis.
The commonly used shampoos may contain one or more of the following active ingredients to control the seborrhoea:
- salicylic acid
- zinc pyrithione
- selenium sulfide
If the condition is severe or persistent prescription shampoos and antifungal agents, corticosteroids or calcineurin inhibitors may be needed.