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Questions and Answers About Psoriasis
What Is Psoriasis?
Psoriasis is a chronic (long-lasting) skin
disease characterized by scaling and inflammation. Scaling occurs when
cells in the outer layer of the skin reproduce faster than normal and
pile up on the skins surface.
Psoriasis affects between 1 and 2 percent
of the United States population, or about 5.5 million people. Although
the disease occurs in all age groups and about equally in men and women,
it primarily affects adults. People with psoriasis may suffer discomfort,
including pain and itching, restricted motion in their joints, and emotional
In its most typical form, psoriasis results
in patches of thick, red skin covered with silvery scales. These patches,
which are sometimes referred to as plaques, usually itch and may burn.
The skin at the joints may crack. Psoriasis most often occurs on the
elbows, knees, scalp, lower back, face, palms, and soles of the feet
but it can affect any skin site. The disease may also affect the fingernails,
the toenails, and the soft tissues inside the mouth and genitalia. About
15 percent of people with psoriasis have joint inflammation that produces
arthritis symptoms. This condition is called psoriatic arthritis.
hat Causes Psoriasis?
Recent research indicates that psoriasis
is likely a disorder of the immune system. This system includes a type
of white blood cell, called a T cell, that normally helps protect the
body against infection and disease. Scientists now think that, in psoriasis,
an abnormal immune system causes activity by T cells in the skin. These
T cells trigger the inflammation and excessive skin cell reproduction
seen in people with psoriasis.
In about one-third of the cases, psoriasis
is inherited. Researchers are studying large families affected by psoriasis
to identify a gene or genes that cause the disease. (Genes govern every
bodily function and determine the inherited traits passed from parent
People with psoriasis may notice that there
are times when their skin worsens, then improves. Conditions that may
cause flareups include changes in climate, infections, stress, and dry
skin. Also, certain medicines, most notably beta-blockers, which are
used to treat high blood pressure, and lithium or drugs used to treat
depression, may trigger an outbreak or worsen the disease.
How Is Psoriasis
Doctors usually diagnose psoriasis after
a careful examination of the skin. However, diagnosis may be difficult
because psoriasis can look like other skin diseases. A pathologist may
assist with diagnosis by examining a small skin sample (biopsy) under
There are several forms of psoriasis. The
most common form is plaque psoriasis (its scientific name is
psoriasis vulgaris). In plaque psoriasis, lesions have a reddened base
covered by silvery scales. Other forms of psoriasis include
- Guttate psoriasis--Small, drop-like
lesions appear on the trunk, limbs, and scalp. Guttate psoriasis is most often triggered by bacterial infections (for example, Streptococcus).
- Pustular psoriasis--Blisters of
noninfectious pus appear on the skin. Attacks of pustular psoriasis
may be triggered by medications, infections, emotional stress, or
exposure to certain chemicals. Pustular psoriasis may affect either
small or large areas of the body.
- Inverse psoriasis--Large, dry,
smooth, vividly red plaques occur in the folds of the skin near
the genitals, under the breasts, or in the armpits. Inverse psoriasis
is related to increased sensitivity to friction and sweating and may be painful or itchy.
- Erythrodermic psoriasis--Widespread
reddening and scaling of the skin is often accompanied by itching
or pain. Erythrodermic psoriasis may be precipitated by severe sunburn,
use of oral steroids (such as cortisone), or a drug-related rash.
Are Available for Psoriasis?
Doctors generally treat psoriasis in steps
based on the severity of the disease, the extent of the areas involved,
the type of psoriasis, or the patients responsiveness 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 focuses on light treatments (phototherapy). Step 3 involves taking
medicines internally, usually by mouth (systemic treatment).
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 commonly 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 resistance or adverse reactions
occur. Treatment depends on the location of lesions, their size, the
amount of the skin affected, previous response to treatment, and patients
perceptions about their skin condition and preferences for treatment.
In addition, treatment is often tailored to the specific form of the
Treatments applied directly to the skin are sometimes
effective in clearing psoriasis. Doctors find that some patients respond
well to sunlight, corticosteroid ointments, medicines derived from
vitamin D3, vitamin A (retinoids), coal tar, or anthralin.
Other topical measures, such as bath solutions and moisturizers, may
be soothing but are seldom strong enough to clear lesions over the
long term and may need to be combined with more potent remedies.
- Sunlight--Daily, regular, short doses of sunlight that
do not produce a sunburn clear psoriasis in many people.
- Corticosteroids--Available in
different strengths, corticosteroids (cortisone) are usually applied
twice a day. Short-term treatment is often effective in improving
but not completely clearing psoriasis. If less than 10 percent of
the skin is involved, some doctors will begin treatment with a high-potency
corticosteroid ointment (for example, Diprolene®,* Temovate®,
Ultravate®, or Psorcon®). High-potency steroids
may also be used for treatment-resistant plaques, particularly those
on the hands or feet. Long-term use or overuse of high-potency steroids
can lead to worsening of the psoriasis, thinning of the skin, internal
side effects, and resistance to the treatments benefits. Medium-potency
corticosteroids may be used on the torso or limbs; low-potency preparations
are used on delicate skin areas.
*Brand names included in this fact sheet begin
with a capital letter and are provided as examples only. Their
inclusion does not mean that these products are endorsed by the
National Institutes of Health or any other Government agency.
Also, if a particular brand name is not mentioned, this does not
mean or imply that the product is unsatisfactory.
- Calcipotriene--This drug is a
synthetic form of vitamin D3. (It is not the same as
vitamin D supplements.) Applying calcipotriene ointment (for example,
Dovonex®) twice a day controls excessive production of
skin cells. Because calcipotriene can irritate the skin, however,
it is not recommended for the face or genitals. After 4 months of
treatment, about 60 percent of patients have a good to excellent
response. The safety of using the drug for cases affecting more
than 20 percent of the skin is unknown, and using it on widespread
areas of the skin may raise the amount of calcium in the body to
- Coal tar--Coal tar may be applied
directly to the skin, used in a bath solution, or used on the scalp
as a shampoo. It is available in different strengths, but the most
potent form may be irritating. It is sometimes combined with ultraviolet
B (UVB) phototherapy. Compared with steroids, coal tar has fewer
side effects, but it is messy and less effective and thus is not
popular with many patients. Other drawbacks include its failure
to provide long-term help for most patients, its strong odor, and
its tendency to stain skin or clothing.
- Anthralin--Doctors sometimes use
a 15- to 30-minute application of anthralin ointment, cream, or
paste to treat chronic psoriasis lesions. However, this treatment
often fails to adequately clear lesions, it may irritate the skin,
and it stains skin and clothing brown or purple. In addition, anthralin
is unsuitable for acute or actively inflamed eruptions.
- Topical retinoid--The retinoid
tazarotene (Tazorac) is a fast-drying, clear gel that is applied
to the surface of the skin. Although this preparation does not act
as quickly as topical corticosteroids, it has fewer side effects.
Because it is irritating to normal skin, it should be used with
caution in skin folds. Women of childbearing age should use birth
control when using tazarotene.
- Salicylic acid--Salicylic acid
is used to remove scales, and is most effective when combined with
topical steroids, anthralin, or coal tar.
- Bath solutions--People with psoriasis
may find that bathing in water with an oil added, then applying
a moisturizer, can soothe their skin. Scales can be removed and
itching reduced by soaking for 15 minutes in water containing a
tar solution, oiled oatmeal, Epsom salts, or Dead Sea salts.
- Moisturizers--When applied regularly
over a long period, moisturizers have a cosmetic and soothing effect.
Preparations that are thick and greasy usually work best because
they hold water in the skin, reducing the scales and the itching.
Ultraviolet (UV) light from the sun causes the activated
T cells in the skin to die, a process called apoptosis. Apoptosis
reduces inflammation and slows the overproduction of skin cells that
causes scaling. Daily, short, nonburning exposure to sunlight clears
or improves psoriasis in many people. Therefore, sunlight may be included
among initial treatments for the disease. A more controlled form of
artificial light treatment may be used in mild psoriasis (UVB phototherapy)
or in more severe or extensive psoriasis (psoralen and ultraviolet
A [PUVA] therapy).
UVB phototherapy--Some artificial
sources of UVB light are similar to sunlight. Newer sources, called
narrow-band UVB, emit the part of the ultraviolet spectrum band
that is most helpful for psoriasis. Some physicians will start with
UVB treatments instead of topical agents. UVB phototherapy is also
used to treat widespread psoriasis and lesions that resist topical
treatment. This type of phototherapy is normally administered in
a doctors office by using a light panel or light box, although
some patients can use UVB light boxes at home with a doctors
guidance. Generally at least three treatments a week for 2 or 3
months are needed. UVB phototherapy may be combined with other treatments
as well. 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, which is left on the skin
for 6 to 24 hours. A similar regime, the Goeckerman treatment, involves
application of coal tar ointment and UVB phototherapy.
PUVA--This treatment combines
oral or topical administration of a medicine called psoralen with
exposure to ultraviolet A (UVA) light. Psoralen makes the body more
sensitive to this light. PUVA is normally used when more than 10
percent of the skin is affected or when rapid clearing is required
because the disease interferes with a persons occupation (for
example, when a models face or a carpenters hands are
involved). Compared with 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 short-term
side effects, including nausea, headache, fatigue, burning, and
itching. Long-term treatment is associated with an increased
risk of squamous cell and melanoma skin cancers. PUVA can be
combined with some oral medications (retinoids and hydroxyurea)
to increase its effectiveness. Simultaneous use of drugs that suppress
the immune system, such as cyclosporine, have little beneficial
effect and increase the risk of cancer. In very rare cases, patients
who must travel long distances for PUVA treatments may, with a physicians
close supervision, be taught to administer this treatment at home.
For more severe forms of psoriasis, doctors
sometimes prescribe medicines that are taken internally:
- Methotrexate--This treatment,
which can be taken by pill or injection, slows cell production by
suppressing the immune system. 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 with long-term liver
disease or anemia. Methotrexate should not be used by pregnant women,
by women who are planning to get pregnant, or by their male partners.
- Cyclosporine--Taken orally, cyclosporine
(Neoral®) acts by suppressing the immune system in a
way that slows the rapid turnover of skin cells. It may provide
quick relief of symptoms, but it is usually effective only during
the course of treatment. The best candidates for this therapy are
those with severe psoriasis who have not responded to or cannot
tolerate other systemic therapies. Cyclosporine may impair kidney
function or cause high blood pressure (hypertension), so patients
must be carefully monitored by a doctor. Also, cyclosporine is not
recommended for patients who have a weak immune system, those who
have had substantial exposure to UVB or PUVA in the past, or those
who are pregnant or breast-feeding.
- Hydroxyurea (Hydrea®)--Compared
with methotrexate and cyclosporine, hydroxyurea is less toxic but
also less effective. It is sometimes combined with PUVA or UVB.
Possible side effects include anemia and a decrease in white blood
cells and platelets. Like methotrexate and cyclosporine, hydroxyurea
must be avoided by pregnant women or those who are planning to become
- 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. Most patients
experience a recurrence of psoriasis after acitretin is discontinued.
- Antibiotics--Although not indicated
in routine treatment, antibiotics may be employed when an infection,
such as Streptococcus, triggers the outbreak of psoriasis,
as in certain cases of guttate psoriasis.
What Are Some Promising
Areas of Psoriasis Research?
Researchers continue to search for genes
that contribute to the inherited and other causes of psoriasis. Scientists
are also working to improve our understanding of what happens in the
body to trigger this disease. In addition, much research is focused
on developing new and better treatments. Some of these experimental
treatments, such as agents directed at the specific types of T cells
involved, work to improve the disease with less overall suppression
of the immune system.
How Can People
Contribute to Psoriasis Research?
The National Psoriasis Tissue Bank, which is supported
by the National Psoriasis Foundation, is helping researchers worldwide
study the inherited tendency toward psoriasis. The tissue bank has
DNA from the white blood cells of more than 250 families affected
by the disease. There is particular interest in large families in
which psoriasis is both common and spans two or more generations.
More recently, the tissue bank has begun research involving families
having at least two siblings with psoriasis. People seeking more information
or families interested in participating in a study should contact
National Psoriasis Foundation Tissue
6600 SW 92nd Avenue
Portland, OR 97223-7195
World Wide Web address: http://www.psoriasis.org
Where Can People
Find More Information About Psoriasis?
National Psoriasis Foundation
6600 SW 92nd Avenue, Suite 300
Portland, OR 97223-7195
World Wide Web address: http://www.psoriasis.org
The National Psoriasis Foundation provides physician
referrals and publishes pamphlets and newsletters that include information
on support groups, research, and new drugs and other treatments.
The foundation also promotes community awareness of psoriasis.
National Institute of Arthritis and Musculoskeletal
and Skin Diseases Information Clearinghouse
1 AMS Circle
Bethesda, MD 20892-3675
NIAMS Fast Facts--For health information that is available by fax
24 hours a day, call 301/881-2731 from a fax machine telephone.
This clearinghouse, a public service sponsored by
the National Institute of Arthritis and Musculoskeletal and Skin
Diseases (NIAMS), provides information about various forms of these
diseases. The clearinghouse distributes patient and professional
education materials and also refers people to other sources of information.
The NIAMS gratefully acknowledges the
assistance of Alan N. Moshell, M.D., of NIAMS; Gerald G. Krueger, M.D.,
of the University of Utah; Robert Stern, M.D., of Beth Israel Deaconess
Medical Center in Boston, MA; and the National Psoriasis Foundation
in the review and update of this fact sheet.
The National Institute of Arthritis and Musculoskeletal
and Skin Diseases (NIAMS), a part of the National Institutes
of Health (NIH), leads the Federal medical research effort in
arthritis and musculoskeletal and skin diseases. The NIAMS supports
research and research training throughout the United States,
as well as on the NIH campus in Bethesda, MD, and disseminates
health and research information. The National Institute of Arthritis
and Musculoskeletal and Skin Diseases Information Clearinghouse
is a public service sponsored by the NIAMS that provides health
information and information sources. Additional information
can be found on the NIAMS Web site at http://www.niams.nih.gov/.
Antibodies: Special proteins, produced
by the body's immune system, that help fight and destroy viruses,
bacteria, and other foreign substances that invade the body.
Autoantibodies: Abnormal antibodies
produced against the body's own tissues.
Autoimmune disease: A disease
in which the immune system destroys or attacks a person's own
Cytokines: Chemical messengers in
the body that help direct and regulate response and are involved
in cell-to-cell communication.
Dermis: The layer of skin beneath the
Emollient: A substance composed of
fat or oil that soothes and softens the skin.
Epidermis: The outermost layer of
A form of psoriasis characterized by widespread reddening and
scaling of the skin often accompanied by itching or pain. Symptoms
may be precipitated by severe sunburn, use of oral steroids,
or a drug-related rash.
Gene: A unit of inheritance that contains
the instructions, or code, that a cell uses to make a specific
product, usually a protein. Genes are made of a substance called
DNA. They govern every body function and determine inherited
traits passed from parent to child.
Genetics: The science of understanding
how diseases, conditions, and traits are inherited.
Guttate psoriasis: A form
of psoriasis characterized by drop-like lesions on the trunk,
limbs, and scalp. Symptoms may be triggered by viral respiratory
infections or certain bacterial (streptococcal) infections.
The study of a tissue specimen by staining it and examining
it under a microscope.
Inflammation: A characteristic
reaction of tissues to injury or disease. It is marked by four
signs: swelling, redness, heat, and pain.
Immune response: The reactions
of the immune system to foreign substances.
Immune system: A complex network
of specialized cells and organs that work together to defend
the body against attacks by foreign substances, such as bacteria
Inverse psoriasis: A form
of psoriasis characterized by large, dry, smooth, vividly red
plaques in the folds of skin.
Keratolytic: A substance that promotes
the softening and peeling of the epidermis.
Phototherapy: Use of natural or
artificial light to treat a disease.
Plaques: Patches of thickened and reddened
skin that are covered by silvery scales.
Psoriasis: A chronic (long-lasting)
skin disease characterized by scaling and inflammation. Scaling
occurs when cells in the outer layer of skin reproduce faster
than normal and pile up on the skin's surface. Possibly a disorder
of the immune system.
Psoriasis vulgaris: The
most common form of psoriasis, characterized by reddened lesions
covered by silvery scales.
Psoriatic arthritis: Joint
inflammation that occurs in about 10 percent of people with
PUVA: A treatment sometimes used for extensive
or severe psoriasis that combines oral or topical administration
of a medicine called psoralen with exposure to ultraviolet A
Systemic treatment: A treatment,
such as a pill, that is taken internally.
Topical agent: A treatment, such
as a cream, salve, or ointment, that is applied to the surface
of the skin.
Toxicity: The potential of a drug
or treatment to cause harmful side effects.
T cell: A type of white blood cell that
is part of the immune system and normally helps protect the
body against infection and disease. In psoriasis, it also can
trigger inflammation and excessive skin cell reproduction.
UVB phototherapy: An artificial
light treatment used for mild psoriasis.
Information provided by:
National Institute of Arthritis and Musculoskeletal and Skin Diseases
Publication Date: September 1999
Last Update: January 2002