Eczema and atopic dermatitis
Written by Dr A Sahota, Department of Dermatology, Royal Free Hospital and Dr M Rustin, Department of Dermatology, Royal Free Hospital
What is eczema?
Eczema is the general term used to describe various itchy skin diseases. It is not a very precise term and the disease that most people call ‘eczema’ is known medically as ‘atopic dermatitis’. Dermatitis simply means inflammation of the skin.
What is atopic dermatitis?
Atopic dermatitis is a very common skin problem. It affects approximately 20 per cent of children at some point but most of them grow out of it. But approximately 2 to 4 per cent of the adult population is affected. In the last 30 years, atopic dermatitis has become more common in the United States, South America and European countries.
What causes atopic dermatitis?
Atopic dermatitis is caused by a combination of genetic and environmental factors:
- Genetic factors
Atopic dermatitis tends to run in families. A child with atopic dermatitis is likely to have another atopic condition, such as asthma or hay fever, or at least be related to someone with one.
Several genes have been linked to atopic dermatitis although the connection is not clear. It is likely that a complex combination of genes allows an environmental trigger to cause atopic dermatitis.
- House dust mites.
- Skin infections, such as the bacterium Staphylococcus aureus.
- Food, particularly cow’s milk, eggs or occasionally soy.
- Hard water as you may need to use more soap, which irritates the skin.
- Fewer childhood infections.
What are the symptoms of atopic dermatitis?
Itching in association with either wet, weeping skin or dry, scaly red skin, which affects:
- skin creases around the neck, in the elbows and knees, and on the wrist and ankles.
- the face (especially around the eyes), the scalp, and in severe cases the whole body.
With an infection the skin can become sore and crusted. This may be a sign of infection either with bacteria (usually staphylococcus) or less commonly with the cold sore virus (herpes simplex).
How is atopic dermatitis diagnosed?
Your doctor can usually diagnose eczema by simply looking at the affected area. He may also take a family history of atopic diseases such as asthma or hay fever. You may also need a blood test to help identify the trigger to the condition, eg dog or cat hair, dust, pollen or diet.
What else could it be?
It may be allergic contact dermatitis, caused by an allergy to nickel, perfumes, or preservatives in creams and emollients. The disease can also be confused with scabies.
Atopic dermatitis treatment and cure
There is no cure for this condition but several treatments can reduce its severity.
Emollients or moisturisers can help reduce redness and itchiness and also make other treatment, especially topical corticosteroids, more effective.
Topical corticosteroids (anti-inflammatory creams, ointments, gels or solutions) reduce the severity of the problem within a few days. Sometimes they are combined with antibacterial ingredients to treat infected skin. They are perfectly safe when used properly.
Phototherapy is a form of treatment using artificial light. There are two types: ultraviolet B (UVB) and psoralen + ultraviolet A (PUVA). Both are done in hospital outpatient departments and need to be given two to three times each week for six weeks or more. Although highly effective, treatment must be limited as excess exposure to these lights can cause skin cancers.
Corticosteroid tablets or injections can temporarily clear severe atopic dermatitis in a few days. However, patients suffer side effects if they use them for more than two weeks.
Ciclosporin is an immunosuppressant (a medicine that suppresses the immune system) used in people with severe atopic dermatitis, and can control symptoms even several months after treatment has stopped. But it can also cause kidney damage.
Azathioprine is another immunosuppressant effective in treating atopic dermatitis. However it can affect the bone marrow and the liver.
Mycophenolate mofetil is similar in its actions to azathioprine. It can also affect the bone marrow.
Chinese herbs can be beneficial for some patients, taken either as a tea or applied to the skin. They can also have side effects including liver and kidney damage. The herbs are usually not available on the NHS and can be expensive.
What other treatments are available?
Antibiotics are sometimes prescribed if the atopic dermatitis is infected. The commonest infection is a bacterium called Staphylococcus aureus, which causes a yellowish crust on the affected area. The antibiotic usually prescribed is flucloxacillin (or erythromycin if a person is allergic to penicillin).
Antiviral medicines may be needed if the atopic dermatitis becomes infected with the cold sore virus (herpes simplex). The doctor may prescribe aciclovir to be taken as a tablet or syrup. In severe cases, treatment should be given in hospital through a drip.
Antihistamines are useful for patients, particularly children, who cannot sleep because they feel so itchy. Only antihistamines that have a sedative side effect are effective. They are available as tablets and syrups.
Wet wraps are a type of fabric dressing that is soaked in warm water and then made into a suit to cover the whole body. A second dry layer is put on top of this. These need to be changed daily.
Bandages can also prevent sufferers from scratching their arms and legs.
Evening primrose oil has a mild anti-inflammatory effect and is sometimes recommended for children with mild skin condition. It is usually taken as capsules.
How can I help myself?
Take good care of your skin, moisturising it everyday. Cleanse your skin with a cream (eg aqueous cream) or an ointment (eg emulsifying ointment) rather than soap. Even ‘gentle’ or ‘hypoallergenic’ soaps dry the skin and this makes atopic dermatitis worse. Avoid scratching the itch, as this will make the skin darker, thicker and even itchier.
Reduce the number of dust mites:
- cover the mattress with a plastic sheet, which is damp dusted weekly
- vacuum carpets, beds and soft furnishing weekly
- avoid putting clothing onto carpets
- use a synthetic pillow instead of feather/down
- regularly wash soft toys at 50ºC or higher
- damp dust whole house weekly
- replace carpets with hard flooring if possible.