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Back to Dermatology Diseases
Psoriasis
Psoriasis is a disease whose main symptom is gray or silvery flaky
patches on the skin which are red and inflamed underneath when
scratched. In the United States, it affects 2 to 2.6 percent of the
population, or between 5.8 and 7.5 million people. Commonly affected
areas include the scalp, elbows, knees, navel, and groin. Psoriasis is
autoimmune in origin, and is not contagious. Around a quarter of
people with psoriasis also suffer from psoriatic arthritis, which is
similar to rheumatoid arthritis in its effects.
Causes
Psoriasis is driven by the immune system, especially involving a type
of white blood cell called a T cell. Normally, T cells help protect
the body against infection and disease. In the case of psoriasis, T
cells are put into action by mistake and become so active that they
trigger other immune responses, which lead to inflammation and to
rapid turnover of skin cells. These cells pile up on the surface of
the skin, forming itchy patches or plaques. The first outbreak of
psoriasis is often triggered by emotional or mental stress or physical
skin injury, but heredity is a major factor as well. In about
one-third of the cases, there is a family history of psoriasis.
Researchers have studied a large number of families affected by
psoriasis and identified genes linked to the disease. (Genes govern
every bodily function and determine the inherited traits passed from
parent to child.) People with psoriasis may notice that there are
times when their skin worsens, then improves. Conditions that may
cause flareups include infections, stress, and changes in climate that
dry the skin. Also, certain medicines, including lithium and beta
blockers, which are prescribed for high blood pressure, may trigger an
outbreak or worsen the disease.
Types of Psoriasis
Plaque psoriasis
Skin lesions are red at the base and covered by silvery scales.
Guttate psoriasis
Small, drop-shaped lesions appear on the trunk, limbs, and scalp.
Guttate psoriasis is most often triggered by upper respiratory
infections (for example, a sore throat caused by streptococcal
bacteria).
Pustular psoriasis
Blisters of noninfectious pus appear on the skin. Attacks of pustular
psoriasis may be triggered by medications, infections, stress, or
exposure to certain chemicals.
Inverse psoriasis
Smooth, red patches occur in the folds of the skin near the genitals,
under the breasts, or in the armpits. The symptoms may be worsened by
friction and sweating.
Erythrodermic psoriasis
Widespread reddening and scaling of the skin may be a reaction to
severe sunburn or to taking corticosteroids (cortisone) or other
medications. It can also be caused by a prolonged period of increased
activity of psoriasis that is poorly controlled.
Psoriatic arthritis
Joint inflammation that produces symptoms of arthritis in patients who
have or will develop psoriasis.
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Effect on the Quality of Life
Individuals with psoriasis may experience significant physical
discomfort and some disability. Itching and pain can interfere with
basic functions, such as self-care, walking, and sleep. Plaques on
hands and feet can prevent individuals from working at certain
occupations, playing some sports, and caring for family members or a
home. The frequency of medical care is costly and can interfere with
an employment or school schedule. People with moderate to severe
psoriasis may feel self-conscious about their appearance and have a
poor self-image that stems from fear of public rejection and
psychosexual concerns. Psychological distress can lead to significant
depression and social isolation.
Treatment
Doctors generally treat psoriasis in steps based on the severity of
the disease, size of the areas involved, type of psoriasis, and the
patient's response to initial treatments. This is sometimes called the
"1-2-3" approach. In step 1, medicines are applied to the skin
(topical treatment). Step 2 uses ultraviolet ("light") treatments
(phototherapy). Step 3 involves taking medicines by mouth or injection
that treat the whole immune system (called systemic therapy).
Over time, affected skin can become resistant to treatment, especially
when topical corticosteroids are used. Also, a treatment that works
very well in one person may have little effect in another. Thus,
doctors often use a trial-and-error approach to find a treatment that
works, and they may switch treatments periodically (for example, every
12 to 24 months) if a treatment does not work or if adverse reactions
occur.
Topical Treatment
Treatments applied directly to the skin may improve its condition.
Doctors find that some patients respond well to ointment or cream
forms of corticosteroids, vitamin D3, retinoids, coal tar, or
anthralin. Bath solutions and moisturizers may be soothing, but they
are seldom strong enough to improve the condition of the skin.
Therefore, they usually are combined with stronger remedies.
Corticosteroids
These drugs reduce inflammation and the turnover of skin cells, and
they suppress the immune system. Available in different strengths,
topical corticosteroids (cortisone) are usually applied to the skin
twice a day. Short-term treatment is often effective in improving, but
not completely eliminating, psoriasis. Long-term use or overuse of
highly potent (strong) corticosteroids can cause thinning of the skin,
internal side effects, and resistance to the treatment's benefits. If
less than 10 percent of the skin is involved, some doctors will
prescribe a high-potency corticosteroid ointment. High-potency
corticosteroids may also be prescribed for plaques that don't improve
with other treatment, particularly those on the hands or feet. In
situations where the objective of treatment is comfort, medium-potency
corticosteroids may be prescribed for the broader skin areas of the
torso or limbs. Low-potency preparations are used on delicate skin
areas. (Note: Brand names for the different strengths of
corticosteroids are too numerous to list.)
Calcipotriene
This drug is a synthetic form of vitamin D3 that can be applied to the
skin. Applying calcipotriene ointment (for example, Dovonex*) twice a
day controls the speed of turnover of skin cells. Because
calcipotriene can irritate the skin, however, it is not recommended
for use on the face or genitals. It is sometimes combined with topical
corticosteroids to reduce irritation. Use of more than 100 grams of
calcipotriene per week may raise the amount of calcium in the body to
unhealthy levels.
Retinoids
Topical retinoids are synthetic forms of vitamin A. The retinoid
tazarotene (Tazorac) is available as a gel or cream that is applied to
the skin. If used alone, this preparation does not act as quickly as
topical corticosteroids, but it does not cause thinning of the skin or
other side effects associated with steroids. However, it can irritate
the skin, particularly in skin folds and the normal skin surrounding a
patch of psoriasis. It is less irritating and sometimes more effective
when combined with a corticosteroid. Because of the risk of birth
defects, women of childbearing age must take measures to prevent
pregnancy when using tazarotene.
Coal tar
Preparations containing coal tar (gels and ointments) may be applied
directly to the skin, added (as a liquid) to the bath, or used on the
scalp as a shampoo. Coal tar products are available in different
strengths, and many are sold over the counter (not requiring a
prescription). Coal tar is less effective than corticosteroids and
many other treatments and, therefore, is sometimes combined with
ultraviolet B (UVB) phototherapy for a better result. The most potent
form of coal tar may irritate the skin, is messy, has a strong odor,
and may stain the skin or clothing. Thus, it is not popular with many
patients.
Anthralin
Anthralin reduces the increase in skin cells and inflammation. Doctors
sometimes prescribe a 15- to 30-minute application of anthralin
ointment, cream, or paste once each day to treat chronic psoriasis
lesions. Afterward, anthralin must be washed off the skin to prevent
irritation. This treatment often fails to adequately improve the skin,
and it stains skin, bathtub, sink, and clothing brown or purple. In
addition, the risk of skin irritation makes anthralin unsuitable for
acute or actively inflamed eruptions.
Salicylic acid
This peeling agent, which is available in many forms such as
ointments, creams, gels, and shampoos, can be applied to reduce
scaling of the skin or scalp. Often, it is more effective when
combined with topical corticosteroids, anthralin, or coal tar.
Clobetasol propionate
This is a foam topical medication (Olux), which has been approved for
the treatment of scalp and body psoriasis. The foam penetrates the
skin very well, is easy to use, and is not as messy as many other
topical medications.
Bath solutions
People with psoriasis may find that adding oil when bathing, then
applying a moisturizer, soothes their skin. Also, individuals can
remove scales and reduce itching by soaking for 15 minutes in water
containing a coal tar solution, oiled oatmeal, Epsom salts, or Dead
Sea salts.
Moisturizers
When applied regularly over a long period, moisturizers have a
soothing effect. Preparations that are thick and greasy usually work
best because they seal water in the skin, reducing scaling and
itching.
Light Therapy
Natural ultraviolet light from the sun and controlled delivery of
artificial ultraviolet light are used in treating psoriasis.
Sunlight
Much of sunlight is composed of bands of different wavelengths of
ultraviolet (UV) light. When absorbed into the skin, UV light
suppresses the process leading to disease, causing activated T cells
in the skin to die. This process reduces inflammation and slows the
turnover of skin cells that causes scaling. Daily, short, nonburning
exposure to sunlight clears or improves psoriasis in many people.
Therefore, exposing affected skin to sunlight is one initial treatment
for the disease.
Ultraviolet B (UVB) phototherapy
UVB is light with a short wavelength that is absorbed in the skin's
epidermis. An artificial source can be used to treat mild and moderate
psoriasis. Some physicians will start treating patients with UVB
instead of topical agents. A UVB phototherapy, called broadband UVB,
can be used for a few small lesions, to treat widespread psoriasis, or
for lesions that resist topical treatment. This type of phototherapy
is normally given in a doctor's office by using a light panel or light
box. Some patients use UVB light boxes at home under a doctor's
guidance.
A newer type of UVB, called narrowband UVB, emits the part of the
ultraviolet light spectrum band that is most helpful for psoriasis.
Narrowband UVB treatment is superior to broadband UVB, but it is less
effective than PUVA treatment (see next paragraph). It is gaining in
popularity because it does help and is more convenient than PUVA. At
first, patients may require several treatments of narrowband UVB
spaced close together to improve their skin. Once the skin has shown
improvement, a maintenance treatment once each week may be all that is
necessary. However, narrowband UVB treatment is not without risk. It
can cause more severe and longer lasting burns than broadband
treatment.
Psoralen and ultraviolet A phototherapy (PUVA)
This treatment combines oral or topical administration of a medicine
called psoralen with exposure to ultraviolet A (UVA) light. UVA has a
long wavelength that penetrates deeper into the skin than UVB.
Psoralen makes the skin more sensitive to this light. PUVA is normally
used when more than 10 percent of the skin is affected or when the
disease interferes with a person's occupation (for example, when a
teacher's face or a salesperson's hands are involved). Compared with
broadband UVB treatment, PUVA treatment taken two to three times a
week clears psoriasis more consistently and in fewer treatments.
However, it is associated with more shortterm side effects, including
nausea, headache, fatigue, burning, and itching. Care must be taken to
avoid sunlight after ingesting psoralen to avoid severe sunburns, and
the eyes must be protected for one to two days with UVA-absorbing
glasses. Long-term treatment is associated with an increased risk of
squamous-cell and, possibly, melanoma skin cancers. Simultaneous use
of drugs that suppress the immune system, such as cyclosporine, have
little beneficial effect and increase the risk of cancer.
Light therapy combined with other therapies
Studies have shown that combining ultraviolet light treatment and a
retinoid, like acitretin, adds to the effectiveness of UV light for
psoriasis. For this reason, if patients are not responding to light
therapy, retinoids may be added. UVB phototherapy, for example, may be
combined with retinoids and other treatments. One combined therapy
program, referred to as the Ingram regime, involves a coal tar bath,
UVB phototherapy, and application of an anthralin-salicylic acid paste
that is left on the skin for 6 to 24 hours. A similar regime, the
Goeckerman treatment, combines coal tar ointment with UVB
phototherapy. Also, PUVA can be combined with some oral medications
(such as retinoids) to increase its effectiveness.
Systemic Treatment
For more severe forms of psoriasis, doctors sometimes prescribe
medicines that are taken internally by pill or injection. This is
called systemic treatment. Recently, attention has been given to a
group of drugs called biologics (for example, alefacept and etanercept),
which are made from proteins produced by living cells instead of
chemicals. They interfere with specific immune system processes.
Methotrexate
Like cyclosporine, methotrexate slows cell turnover by suppressing the
immune system. It can be taken by pill or injection. Patients taking
methotrexate must be closely monitored because it can cause liver
damage and/or decrease the production of oxygen-carrying red blood
cells, infection-fighting white blood cells, and clot-enhancing
platelets. As a precaution, doctors do not prescribe the drug for
people who have had liver disease or anemia (an illness characterized
by weakness or tiredness due to a reduction in the number or volume of
red blood cells that carry oxygen to the tissues). It is sometimes
combined with PUVA or UVB treatments. Methotrexate should not be used
by pregnant women, or by women who are planning to get pregnant,
because it may cause birth defects.
Retinoids
A retinoid, such as acitretin (Soriatane), is a compound with vitamin
A-like properties that may be prescribed for severe cases of psoriasis
that do not respond to other therapies. Because this treatment also
may cause birth defects, women must protect themselves from pregnancy
beginning 1 month before through 3 years after treatment with
acitretin. Most patients experience a recurrence of psoriasis after
these products are discontinued.
Cyclosporine
Taken orally, cyclosporine acts by suppressing the immune system to
slow the rapid turnover of skin cells. It may provide quick relief of
symptoms, but the improvement stops when treatment is discontinued.
The best candidates for this therapy are those with severe psoriasis
who have not responded to, or cannot tolerate, other systemic
therapies. Its rapid onset of action is helpful in avoiding
hospitalization of patients whose psoriasis is rapidly progressing.
Cyclosporine may impair kidney function or cause high blood pressure
(hypertension). Therefore, patients must be carefully monitored by a
doctor. Also, cyclosporine is not recommended for patients who have a
weak immune system or those who have had skin cancers as a result of
PUVA treatments in the past. It should not be given with phototherapy.
6-Thioguanine
This drug is nearly as effective as methotrexate and cyclosporine. It
has fewer side effects, but there is a greater likelihood of anemia.
This drug must also be avoided by pregnant women and by women who are
planning to become pregnant, because it may cause birth defects.
Hydroxyurea (Hydrea)
Compared with methotrexate and cyclosporine, hydroxyurea is somewhat
less effective. It is sometimes combined with PUVA or UVB treatments.
Possible side effects include anemia and a decrease in white blood
cells and platelets. Like methotrexate and retinoids, hydroxyurea must
be avoided by pregnant women or those who are planning to become
pregnant, because it may cause birth defects.
Alefacept (Amevive)
This is the first biologic drug approved specifically to treat
moderate to severe plaque psoriasis. It is administered by a doctor,
who injects the drug once a week for 12 weeks. The drug is then
stopped for a period of time while changes in the skin are observed
and a decision is made regarding the need or further treatment.
Because alefacept suppresses the immune system, the skin often
improves, but there is also an increased risk of infection or other
problems, possibly including cancer. Monitoring by a doctor is
required, and a patient's blood must be tested weekly around the time
of each injection to make certain that T cells and other immune system
cells are not overly depressed.
Etanercept (Enbrel)
This drug is an approved treatment for psoriatic arthritis where the
joints swell and become inflamed. Like alefacept, it is a biologic
response modifier, which after injection blocks interactions between
certain cells in the immune system. Etanercept limits the action of a
specific protein that is overproduced in the lubricating fluid of the
joints and surrounding tissues, causing inflammation. Because this
same protein is overproduced in the skin of people with psoriatic
arthritis, patients receiving etanercept also may notice an
improvement in their skin. Individuals should not receive etanercept
treatment if they have an active infection, a history of recurring
infections, or an underlying condition, such as diabetes, that
increases their risk of infection. Those who have psoriasis and
certain neurological conditions, such as multiple sclerosis, cannot be
treated with this drug. Added caution is needed for psoriasis patients
who have rheumatoid arthritis; these patients should follow the advice
of a rheumatologist regarding this treatment.
Antibiotics
These medications are not indicated in routine treatment of psoriasis.
However, antibiotics may be employed when an infection, such as that
caused by the bacteria Streptococcus, triggers an outbreak of
psoriasis, as in certain cases of guttate psoriasis.
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