Eczema

Eczema (also called atopic dermatitis or AD) is a chronic skin condition, characterised by itching and surface inflammation (redness and irritation). It is often associated with a personal or family history of problems like hay fever, allergic conjunctivitis (‘allergic eyes’) and asthma. Atopic dermatitis is becoming far more common, as are many other allergic diseases.

The exact cause of eczema is not known; it probably results from the interaction of several factors. The latest research shows that AD sufferers may have a genetic skin-barrier defect. This makes the skin dry and strips it of its natural protection, leaving it vulnerable to infections and substances that may cause allergic reaction or irritation. These patients also seem unusually prone to developing inflammation. People who suffer from atopic dermatitis often have high levels of an immune substance called IgE.

Things that tend to trigger atopic dermatitis flare-ups include: staphylococcus growth on the skin, destruction of the skin barrier, exposure to irritants (e.g. rough clothing like wool, soaps), stress and exposure to allergens. A common sensitivity in AD patients is to the house dust mite – an allergen that is extremely difficult to avoid. This may be assessed using skin-prick tests.

There is no evidence of food allergy in teenagers and adults with eczema, although food allergy may be associated with AD in infants and young children.

• 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 limbs. In older children and adults, it may be more localised and chronic.
• The redness and thickened skin is most commonly found in the creases of the elbows and knees and on the eyelids, neck and wrists. The rash may also spread across the rest of the body.
• The constant itching 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 (often due to scratching) and swollen glands are common.
• Contact dermatitis frequently exacerbates this condition. People with atopic dermatitis often use over-the-counter or prescribed medications, and there are many such substances that irritate the skin.
• Emotional stress, temperature or humidity changes, bacterial infections and rough clothing can aggravate the condition.

Diagnosis is usually clinical: the doctor examines the skin condition and asks the patient questions. Diagnosis 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 GP or dermatologist may recommend patch tests, skin-prick tests or blood tests for specific allergens, but in most cases these are unnecessary. A child might be tested for common food allergies, but this should only be required if there is a poor response to treatment or a very clear history of food-associated flare-ups.

There are several general measures you can take to alleviate symptoms:

• Avoid overheating. (Turn the air conditioner down, etc.)
• Avoid irritants like certain soaps and bubble baths.
• Avoid wearing rough, irritating fabrics (like wool) directly on the skin.
• Avoid activities or occupations that may damage the skin. For example, sports involving long periods in the water 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.

Specific treatments:

• Corticosteroid creams or ointments applied to the skin are the most effective drugs. Such creams are white in colour and disappear when applied to the skin (best for weeping lesions), while ointments are fatty and leave a greasy layer on the skin (best for dry lesions). Prolonged use of high-potency corticosteroid creams should be avoided, particularly in infants. Corticosteroids should be used with extreme caution on the face and skin folds. The main side effect of topical corticosteroids is thinning (atrophy) of the skin, which may damage its appearance. They can also become ineffective with frequent use; alternate their use with simple moisturisers.
• Calcineurin inhibitors, eg.  pimecrolimus and tacrolimus, are relatively new group of topical medications. While there have been some safety concerns, most dermatologists feel comfortable using these medications. They may be a safer alternative in the case of eyelid atopic dermatitis, as there are concerns about using corticosteroid creams near the eye.
• Children may need a sedative antihistamine at bedtime, when the itching is at its worst.
• If home treatment is not effective, the person may need to be treated in hospital.
• Secondary bacterial infections are treated with antibiotics.
• Eczema sufferers should be especially careful about exposure to Herpes simplex (the virus that causes cold sores), as it can sometimes induce serious illness with high temperatures.
• Older adults may benefit from exposure to high-intensity ultraviolet light, along with psoralen, a photosensitising drug (meaning it makes you more sensitive to light).
• In severe cases that do not respond to conventional treatment, oral corticosteroids may be used. Immunosuppressive drugs like cyclosporine, azathioprine, methotrexate and mycophenolate mofetil may also be tried. These drugs are very rarely necessary, and their side effects are severe. It is far better to follow the general advice strictly and apply the creams and ointments diligently.

Prevention

Atopic dermatitis is a chronic disease. This means that it is usually present for the duration of the patient’s life. Approximately 60% of patients grow out of AD, but in those who do not, the disease flares up and calms down in cycles. It is up to the patient to reduce the incidence of severe flare-ups by maintaining the good condition of the skin (by moisturizing and following the other practical advice given above), and by administering rapid treatment when a flare-up does occur.

Reviewed by Dr Bianca Tod, MBBCh (Wits), April 2011