Eczema (atopic dermatitis)
I was too tired to blog today but I thought I owe my friend an examination of eczema as promised. We all know how annoying itchy skin can be. It is getting more and more common and can be stressful.
- Atopic dermatitis is a chronic, itching, superficial inflammation of the skin.
- It is often associated with a personal or family history of other allergy-related problems, such as hay fever and asthma.
- The exact cause is not known, but there is strong evidence for a genetic predisposition.
- Itching is a constant feature.
- Emotional stress, temperature or humidity changes, bacterial skin infections, house dust mite, foodstuffs and wool contact may also aggravate the condition.
This is a chronic, itching, superficial inflammation of the skin, often associated with a personal or family history of related problems such as hay fever, allergic conjunctivitis (‘allergic eyes’) and asthma. Doctors and patients often loosely refer to this condition as ‘eczema’.
The exact cause is not known. It is felt that interaction of many factors leads to the development of atopic dermatitis. The latest research shows that atopic dermatitis sufferers may have a (genetically) inherited skin barrier defect. This makes the skin dry and strips it of its natural protection from infections and substances that may cause an allergic reaction or irritation. These patients also seem unusually prone to develop inflammation. People who suffer from atopic dermatitis often have high levels of an immune substance called IgE.
Atopic dermatitis is becoming far more common, a trend that is being noticed in many other allergic diseases.
Food allergy may be associated with atopic dermatitis in infants and young children; however there is no evidence of any role of food allergy in teenagers and adults. Your GP or dermatologist can test your child for common food allergies with a simple blood test (Fx5) or using skin prick testing. This is only indicated if there is a poor response to treatment or a very clear history of food-associated flares.
A common sensitivity amongst atopic dermatitis patients is to house dust mite. This may be assessed using skin prick tests. This allergen is however extremely difficult to avoid.
Things that tend to cause atopic dermatitis flares include: staphylococcus growth on the skin, destruction of the skin barrier, exposure to allergens, exposure to irritants (e.g. rough clothing like wool, soaps) and stress.
- The pattern of AD tends to change as a person gets older.
- The condition may start within the first few months of life with red, weeping, crusting lesions on the face, scalp, and the limbs.
- In older children or adults it may be more localised and chronic.
- The redness and thickened skin is most commonly found in the creases in the elbows and knees, the eyelids, neck and wrists. The rash may become more widespread across the rest of the body.
- Itching is a constant feature. The constant itch leads to rubbing and scratching, which in turn leads to more itching. Itching is made worse by the dryness commonly observed in these patients.
- Secondary bacterial infections and swollen glands are common.
- Because people with atopic dermatitis often use drugs, over-the-counter or prescribed, contact dermatitis frequently complicates this condition. There are many substances that irritate the skin and can exacerbate the condition.
- Emotional stress, temperature or humidity changes, bacterial skin infections and wool can also aggravate the condition.
Diagnosis is usually clinical – which means the doctor examines the skin condition and asks questions to make the diagnosis. It is based on the location of the lesions, how long they have been there and whether there is a family history of allergic disorders. In some cases, if the doctor is not certain of the diagnosis, he/she may take a piece of skin for examination under a microscope (a biopsy). Your doctor may in some cases recommend patch tests, skin prick tests or blood tests for specific allergens. In most cases these are unnecessary.
There are several general measures:
- Avoid overheating (turn the air conditioner down etc.).
- Avoid irritants like soaps, bubble baths, etc.
- Avoid wearing rough, irritating fabrics like wool directly on the skin.
- Avoid activities or occupations that may damage the skin e.g. sports involving long periods in the water (this may damage the barrier function of the skin).
- Keep baths short and not too hot.
- Immediately after bathing (within minutes), pat (don't rub) the skin dry and apply appropriate moisturiser (emollient).
- There are a multitude of emollients on the market. Frequently used examples are UEA and CMG. Your pharmacist will prepare this for you. Do not use fragranced body lotions!
- Avoid topical (applied to the skin as creams/ointments) antibiotics and antiseptics (these promote bacterial resistance).
- Fingernails should be kept short to minimise damage when scratching.
I am not a dermatologist so visit your doctor for advice.