Eczema - Contact Eczema
What is it
Contact eczema is a skin inflammation caused by contact of the skin with a substance to which the individual has developed an allergy. It is also known as contact dermatitis.
Why does it occur
people can become allergic to a wide range of chemicals. Some of these are everyday substances such as nickel in denim jeans rivets and watch backs, and household latex rubber gloves(1). Some of these are specialised chemicals used in work (such as hairdressing preparations) and industry (such as dyes, oils, preservatives and resins)(2).
How does it occur
The start is when the skin begins to be sensitive to a particular substance (the trigger substance). This is called sensitisation. Sensitisation occurs after many repeated exposures to the trigger, sometimes over years. Eventually the body "learns" to recognise the trigger as a foreign substance, and starts a defence reaction (immune response) to it.
The inflammation of contact eczaema affects the areas of skin in contact with the trigger substance. It starts within 72 hours of contact, and can go on for up to a week.
To complicate matters further, infection can set in. Bacteria are present naturally on the skin surface, and normally cause no trouble (commensal bacteria). In eczema, the body's defences are altered at the site of skin damage, and the normally harmless bacteria enter the wound, multiply and aggravate the symptoms. This is called secondary infection.
Other things can make contact eczema worse, such as other skin irritants (perfumed soaps and bubble baths for example) and temperature changes (cold weather, and excessive heating in bedrooms).
What are the symptoms
Inflammation causes itching, the main symptom of contact eczema. This is due to the release of special compounds from damaged skin tissue(3), which directly stimulate nerve endings. This naturally leads to the urge to scratch, which is almost impossible to resist, and the skin is further damaged by scratching. This sets up a vicious cycle which is then hard to break.
The skin is usually dry and flaky, though if infection sets in, the skin can weep and bleed, becoming quite raw. It can also become blistered(4). Difficulty in sleeping is a common problem in widespread eczema, due to the intense itching. people often scratch themselves in their sleep, making the condition worse still.
What are the complications
Untreated or undertreated eczaema can lead to areas of persistently infected and inflamed skin (chronic eczema). These can eventually become scarred and thickened permanently. This will happen if the skin is continuously exposed to the trigger(5).
psychological complications should not be underestimated. Lack of confidence, poor self-image and misery will all take their toll if eczema is not controlled. people with contact eczema in visible places like the hands often become embarrassed about their appearance.
What are the tests
Allergy testing: This is done by patch testing. Small aluminium discs containing test substances are stuck onto the skin of the back. A standard range of common triggers is used, though specialist centres may have wider ranges. If a particular substance is suspected as being a trigger, then it can be included in the test. The discs are left in place, undisturbed, for 48 hours. They are then removed, and the skin examined for evidence of a response. This is repeated at 72 hours to check for a delayed response. It may then be possible to proved a list of possible triggers so that these can be avoided.
Bacteriology: This is only useful if secondary infection has set in. The skin is swabbed and the swab incubated in a laboratory to see which bacteria are growing and which antibiotics they are sensitive to. The most effective antibiotic treatment can then be chosen.
What is the treatment
Good doctor-patient communication: An important part of treatment is a good explanation of the disorder and how symptoms are produced, and what to expect from the investigation and treatment options.
Avoiding the trigger: This is the main treatment, and is possible if the trigger can be identified, either through careful common-sense detective work or after successful patch testing. Once the trigger has been withdrawn, the eczema can settle within a week of starting treatment, though it will start up again each time the skin is exposed to the trigger.
Drug treatment: This is targeted towards the three main practical problems of contact eczaema: dryness, itchiness, and tendency to infection.
- Soaps and bubble baths tend to dry the skin out. Alternatives are emulsifying ointments, cleansing creams and medical bath oils, which lift skin dirt without drying it out
- Barrier creams help to replace the natural protective mechanism of the skin against external substances. This barrier property is lost in eczaema
- Steroid creams are very useful to reduce itch and calm inflamed skin. They are available in a variety of strengths to suit the severity of the eczema. The mildest and most commonly used is hydrocortisone cream. It is safe and has no long-term side-effects
- Antihistamine tablets or syrups can help to alleviate itching
- Antibiotic creams are used to treat infected eczema
What are the treatment side effects
All drug treatment scan cause allergic rashes and reactions, though these are rare. A careful assessment of their likelihood and whether the risk is worth taking will be made by the prescribing doctor. Lanolin (sheep wool fat) is a common additive in skin preparations, and is a common sensitiser. It is best avoided.
Steroid creams have a reputation for causing permanent skin thinning. This is true of older potent steroids used for a long time, but not of hydrocortisone 0.5 or 1% strengths, the most commonly used.
If a strong steroid is needed for severe eczaema, modern steroids are available which do not thin the skin as much as older ones. Steroids used to treat eczema do not have the side effects of steroid tablets or anabolic steroids used by body-builders. They should not be confused.
What self-help strategies are there
- Avoiding known triggers
- Using treatment regularly and early on in a flare-up.
- Using dressings or bandages to protect the affected area, and reduce damage from scratching. Cotton gloves worn at night can help reduce damage from scratching during sleep.
What about family and friends
Eczema is not catching. Its unsightly appearance can cause social rejection; the embarrassment felt can cause people to withdraw from activities and into themselves.
It is therefore really important that people close to the individual understand eczema, and support the sufferer fully, giving encouragement and positive help wherever possible. This applies strongly to educating others as well.
Where can I get further information
Apart from contacting your Gp, the following organisation may offer further help:
National Eczema Society
163, Eversholt Street
Telephone: 020 7388 4097 (9.30-17.00)
Telephone: 08705 118877 (24 hour recorded information line)
- HUNT, L.W. et. al., (1995) An epidemic of occupational allergy to latex involving health care workers, Journal of Occupational and Environmental Medicine, 37(10) pp.1204-9.
- AGENCY FOR TOXIC SUBSTANCES AND DISEASE REGISTRY (1993) Contact dermatitis and urticaria from environmental exposures, American Family physician, 48(5) pp.773-80.
- FERGUSON, T.A., et. al., (1994) Regulation of contact hypersensitivity by interleukin 10, Journal of Experimental Medicine, 179(5) pp.1597-604.
- KLAUS, M.V., WIESELTHIER, J.S., (1993) Contact dermatitis American Family physician, 48(4) pp.629-32.
- DEL SAVIO, B, SHERERTZ, E.F., (1994) Is allergic contact dermatitis being overlooked Archives of Family Medicine, 3(6) pp.537-43.