PSORIASIS - KEY FACTS
by British Association of Dermatologists
What is psoriasis?
Psoriasis is a common skin disorder affecting about 2% of the population. It
occurs equally in men and women, at any age. The condition is not infectious,
and is often not itchy. Psoriasis does not scar the skin.
What does psoriasis look like?
Patches of psoriasis are red and are covered by silvery white scales. These
patches usually occur on the knees, elbows, trunk or scalp, though any areas of
the skin can be involved.
Your skin and psoriasis
The skin is a complex organ made up of several layers of different types of
cells. Those in the outer layer - the epidermis - gradually change, as they
move towards the surface where they are continually shed. This process normally
takes between 3 and 4 weeks. In psoriasis, this rate of turnover is
dramatically increased within the affected skin, so that the process may take
as little as 3 to 4 days.
What causes psoriasis?
Although the exact cause of psoriasis is not known, some people are clearly
more likely to develop it than others. Many patients know of someone else in
the family who has psoriasis; in other words, it is a genetic or hereditary
disease. However, several factors may start an episode of psoriasis, such as a
throat infection, (especially in children), stress or injury to the skin.
Nevertheless, in most patients who develop psoriasis, or who have a recurrence
of it, no obvious cause can be detected. Usually, sunlight improves the
condition, though occasionally, it may make it worse. A high alcohol intake may
worsen psoriasis. There is no apparent relationship between diet and psoriasis.
How can psoriasis be treated?
Treatment is usually effective. The skin becomes less scaly and may then
look completely normal. However, even if your psoriasis disappears after
treatment, there is a tendency for it to return. But this may not happen for
many years, (or within a few weeks).
Patches of psoriasis on limbs and trunk
The treatment of psoriasis on the limbs and trunk will usually be creams and
ointments your doctor prescribes. Treatments applied directly to the skin are
known as topical therapy.
TOPICAL THERAPY MAY INCLUDE THE FOLLOWING:
Emollients and salicylic acid
Simple emollients such as aqueous cream, or 50% white soft paraffin in
liquid paraffin can reduce scaling - these can be used as frequently as needed.
Preparations containing salicylic acid can be used on heavily scaled plaques -
irritation may occur.
Topical steroids
These preparations are sometimes helpful, but only in certain situations.
The weaker steroids often don't work very well for thick patches of psoriasis,
but may work better on the face or in the skin folds. The stronger steroids
have side effects, one of which may be to make your skin thinner. This is why
their use needs to be closely monitored by your doctor. There is also a
tendency for psoriasis to return quickly when treatment stops.
Tar preparations
You may be prescribed a cosmetically acceptable, medicated tar bath which
will help to remove the loose scales from the patches. Other tar preparations
are cream or ointment formulations. These help most patients but many patients
find them messy and they can stain clothing.
Dithranol
Dithranol is good for uncomplicated psoriasis and can be prescribed for use
at home if you have minor or moderate psoriasis, particularly if the water
washable creams are prescribed. It is almost always used as short contact
therapy.
Short contact therapy
Apply dithranol cream sparingly only to those areas of skin affected by
psoriasis, and rub in gently until it is absorbed, afterwards washing your
hands. Dithranol stains clothes and you should therefore wear old clothes for
the next 30-60 minutes, though you can still carry on with you everyday
activities. After 30-60 minutes, remove the cream by bathing or showering
(using soap or shower gel). The bath or shower should be cleaned immediately
with a proprietary cleanser to avoid permanent staining. Treatment is usually
carried out once daily. As the psoriasis is clearing, you will notice the
treated areas will gradually stain brown. Occasionally, dithranol irritates the
skin causing inflammation and soreness in and around the treated areas.
Psoriasis in the bends of the elbows or knees should not be treated with
dithranol without a doctor's advice, as irritation is likely. Similarly, the
face should not be treated with dithranol without a doctor's advice, as contact
with the eyes must be avoided and skin staining may prove unsightly. The
strength of the dithranol is gradually increased every 3-5 days. If treated
areas become inflamed, treatment should stop until this settles, but may then
be resumed at a lower concentration. Once you can no longer feel the patches of
psoriasis, treatment can stop. Many patients can clear their psoriasis in 6
weeks. The staining goes away over the next couple of weeks. Any new patches
can be treated with the dithranol in the same way. Please note that all
concentrations of any dithranol brand can be dispensed for the cost of a single
prescription charge.
In patient therapy
Some patients do not respond to short contact therapy or their psoriasis may
be too extensive to do this treatment at home. In such circumstances, you may
be treated in a dermatology out-patient unit or sometimes by admission to a
dermatology ward for 3-4 weeks. As an out-patient, you will come each day for 1
to 2 hours, during which you may be given a tar bath, ultraviolet light and
applications of dithranol in a stiffer paste than is used for short contact
treatment. The dithranol will be left on for 24 hours under a tube-gauze
dressing suit, which should reduce dithranol staining of clothing and linen.
Vitamin D analogues
Calcipotriol and Tacalcitol preparations
Recently, two new vitamin D3 preparations, calcipotriol and tacalcitol have
been introduced with considerable success. They are helpful, safe and
cosmetically acceptable. ( But it is important that you tell your doctor if you
are pregnant or breast feeding or if you become pregnant during your
treatment.) Treatment is applied either once daily (tacalcitol) or twice
(calcipotriol) and can be continued for as long as required. Irritation may
occur, especially on the face, bottom and genitals. Treatment should only be
applied to those areas on the specific instructions of the doctor.
Vitamin A analogues
Tazarotene is a new vitamin A gel that is applied once daily to patches of
psoriasis. Irritation may occur if applied to the face or skin folds.
Special sites
Skin folds and face
A weak steroid cream or ointment, or a tar preparation, may be prescribed
and should be used once or twice a day. Regular review by your doctor is
necessary to ensure that the quantities used are within safe limits.
Scalp
A medicated tar or coconut oil shampoo is often prescribed in addition to
steroid or calcipotriol scalp lotion, or a tar or coconut oil preparation. Tar
or coconut oil preparations should be rubbed into the scalp thoroughly, at
night and washed out next morning with the tar shampoo. A shower cap, worn
overnight, helps the treatment penetrate and also protects your pillow case
from stains.
Nails
There is no effective treatment. Nails should be trimmed to prevent
catching.
Moderate and severe psoriasis
There are other methods of treatment for patients whose psoriasis is
considered:
- moderate or severe
- not helped by the simpler topical treatments
- frequently recurring
Unlike the topical treatments described earlier, these involve taking
medication internally or attending a local dermatology centre for ultraviolet
light treatment. The decision to move to this form of treatment will be made by
a senior dermatologist experienced in the management of psoriasis. All the
details will be discussed with you personally and the treatment will be given
under strict hospital supervision. It is important to note these treatments
cannot be used during pregnancy.
Further information
The Psoriasis Association
7 Milton Street
Northampton
NN2 7JG
 01604 711129
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