BAD CONTACT DERMATITIS
by Dr Sarah Wakelin, Skin Allergy Clinic, St John's Institute of
Dermatology, St Thomas' Hospital, London, SE1 7EH
What is dermatitis?
'Dermatitis' or 'eczema' are two words used to describe a common complaint
which produces redness, flaking and cracking of the skin, sometimes with small
water blisters. It is very itchy and may at times feel hot and sore. Repeated
scratching and rubbing leads to thickening of the skin with a dry, wrinkled
appearance.
Are there different types of dermatitis?
There are several different types of dermatitis and these have different
causes. They are broadly divided into those which are constitutional or due to
an 'in-built' tendency and those which are exogenous or due to factors in the
outside world. For example atopic dermatitis or eczema is a constitutional
condition which tends to run in families along with hay fever and asthma.
People are born with the tendency to get this type of eczema although it may
not become a problem until childhood or later life.
What is contact dermatitis?
Contact dermatitis is a dermatitis which is caused by something in the
outside world which comes into contact with the skin. The offending substance
may come into direct contact with the skin or sometimes is carried in the air.
If all further contact with this substance is avoided the dermatitis should get
better.
There are two main types of contact dermatitis - irritant and allergic.
Irritant contact dermatitis is a very common skin problem which
affects many people at some stage of their life. It is caused by contact with
substances which damage the outer layers of the skin and typically affects the
hands. One of the commonest situations giving rise to irritant contact
dermatitis is repeated contact with mildly irritant substances such as water
and detergents (washing-up liquid, soaps, etc.).
Other irritant substances include solvents, eg: petrol, cleaning chemicals,
oils and metalworking fluids used in industry. The skin problem often starts as
chapping, soreness and redness and if untreated leads to a stubborn dermatitis.
Once damaged, the skin is no longer a barrier against the outside world and can
easily be irritated further. This sets up a vicious circle which can be
difficult to break.
People doing certain kinds of work are more at risk of getting irritant
contact dermatitis than others. This includes jobs where the hands are
frequently wet such as hairdressing, catering, cleaning, housework and nursing.
Irritant contact dermatitis may affect people of all ages but is commonest in
adults during their working years.
People who have or have had bad atopic eczema are more vulnerable to
irritant contact dermatitis, as their skin is less resilient to damage by
irritant substances.
Allergic contact dermatitis is less common than irritant contact
dermatitis. It happens because the body's immune system reacts against a
specific substance or 'allergen' which has previously come into contact with
the skin. People are not born with this type of allergy, but develop it during
life, usually in adulthood. Allergic contact dermatitis usually affects only a
minority of people who come into contact with the allergen. What makes an
allergy develop at a certain time is unknown, and why one person gets affected
while others don't is also unclear.
The commonest cause of allergic contact dermatitis in women is nickel, which
is found in metallic jewellery. About one in ten women have this type of
allergy and typically develop itchy sore red patches under inexpensive earrings
after wearing them. Other things that commonly cause allergic contact
dermatitis include perfumes, rubber additives, leather additives and
preservatives in creams and cosmetics. Allergies can also develop to medicated
creams and ointments and sunscreens.
Can a person have more than one kind of dermatitis?
Yes, a person can actually suffer from more than one type of dermatitis. For
example, someone with atopic eczema (i.e. constitutional eczema) who works as a
hairdresser could get skin irritant on their hands from frequent shampooing
(i.e. irritant contact dermatitis) and also develop an allergy to hair dyes
(i.e. allergic contact dermatitis).
What are patch tests?
Patch testing is a special investigation carried out by dermatologists in
hospital. It helps to find out if a person's dermatitis is caused by contact
allergy and identifies what substance(s) are likely to be causing the problem.
Patch testing does not diagnose irritant contact dermatitis and is not used to
investigate other types of allergy such as food allergies.
The tests involve having small quantities of the suspected substances put on
the skin (usually the upper back) under adhesive dressings (patches). The
patches are removed 2 days later, and the skin examined to see if a reaction
has developed to any substance. A final skin examination is usually carried out
after another 2 days or so. The procedure is safe and painless, but the patches
may feel a little itchy. The area of skin where the patches have been applied
should be kept dry throughout the tests. At the final visit, the dermatologist
will inform you if you have any allergies and what steps you need to take to
avoid further contact with these substances in your daily life.
Who can have patch tests?
Patch tests can be carried out in people of most ages, but are not usually
carried out on babies as allergic contact dermatitis is extremely unlikely in
this age group. They are also best avoided during pregnancy.
Examples of common causes of allergic contact dermatitis
Sometimes the results of patch testing are negative and no allergies are
found. This can be helpful as it excludes the likelihood that a dermatitis is
caused by an allergy.
Occupational dermatitis
In some cases a person's dermatitis is caused primarily by substances to
which they are exposed to at work. These may be irritants or allergens
depending on the nature of the job. Patch tests should be carried out if the
work involves exposure to substances which can cause allergy.
Management of contact dermatitis includes the following important
steps:
- Preventing further dermatitis Minimising contact with all irritant
substances at work and at home. Avoiding skin contact with the substances you
are allergic to. General skin care measures to keep the skin strong and
healthy.
- Active Treatment Treatment of the dermatitis with frequent
application of moisturisers and regular use of steroid creams or ointments once
or twice a day. If the dermatitis has become additionally infected a course of
antibiotic cream may be necessary.
General hand care
The hands are one of the commonest parts of the body to be affected with
dermatitis. Because they are so important for carrying out the tasks of daily
life, skin problems here can be especially troublesome. Good general skin care
measures can help to look after the skin and are a major part of the treatment
of hand dermatitis. They include the following:
- Avoid frequent contact with water and use protective gloves where possible
- Use gloves and barrier creams if provided at work
- Avoid direct contact with other harsh substances such as the juices from
fruit and vegetables
- Use a gentle skin cleanser instead of soap for washing with warm water and
dry the hands thoroughly afterwards to prevent chapping
- Use plenty of moisturisers and reapply them frequently (e.g. during tea and
coffee breaks, whilst watching television and before going to sleep at night.
It can take several months for the skin to recover completely from an
episode of dermatitis, so even when it looks apparently normal it is still
vulnerable. Try to find the time to look after your skin and treat it with
respect - its got to last you a lifetime!
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