Psoriasis is a chronic, non-contagious disease characterized by inflamed hyperproliferative lesions covered with silvery-white scabs of dead skin.


Psoriasis, which affects at least four million Americans, is slightly more common in women than in men. Although the disease can develop at any time, 10–15% of all cases are diagnosed in children under 10, and the average age at the onset of symptoms is 28 years of age.

Psoriasis is most common in fair-skinned people and relatively rare in dark-skinned individuals, although the rate among African Americans appears to be slowly rising.

Normal skin cells mature and replace dead skin every 28–30 days. Psoriasis causes skin cells to mature in less than a week. Because the body can’t shed the old skin as rapidly as new cells are rising to the surface, raised patches of dead skin develop on the arms, back, chest, elbows, legs, nails, folds between the buttocks, and scalp.

Psoriasis is considered mild if it affects less than 5% of the surface of the body, moderate if 5–30% of the skin is involved, and severe if the disease affects more than 30% of the body surface.

Types of psoriasis

Dermatologists distinguish different forms of psoriasis according to what part of the body is affected, how severe symptoms are, how long they last, and the pattern formed by the scales.

PLAQUE PSORIASIS. Plaque psoriasis (psoriasis vulgaris), the most common form of the disease, is characterized by small, red bumps that enlarge, become inflamed, and form scales.

The top scales flake off easily and often, but those beneath the surface of the skin clump together. Removing these scales exposes tender skin, which bleeds and causes the plaques (inflamed patches) to grow.

Plaque psoriasis can develop on any part of the body, but most often occurs on the elbows, knees, scalp, and trunk.

SCALP PSORIASIS. At least 50 of every 100 people who have any form of psoriasis have scalp psoriasis. This form of the disease is characterized by scale-capped plaques on the surface of the skull.

NAIL PSORIASIS. The first sign of nail psoriasis is usually pitting of the fingernails or toenails. Size, shape, and depth of the marks vary, and affected nails may thicken, yellow, or crumble. The skin around an affected nail is sometimes inflamed, and the nail may peel away from the nail bed.

GUTTATE PSORIASIS. Named for the Latin word gutta, which means “a drop,” guttate psoriasis is characterized by small, red, drop-like dots that enlarge rapidly and may be somewhat scaly.

Often found on the arms, legs, and trunk and sometimes in the scalp, guttate psoriasis can clear up without treatment or disappear and resurface in the form of plaque psoriasis.

PUSTULAR PSORIASIS. Pustular psoriasis usually occurs in adults. It is characterized by blister-like lesions filled with non-infectious pus and surrounded by reddened skin.

Pustular psoriasis, which can be limited to one part of the body (localized) or can be widespread, may be the first symptom of psoriasis or develop in a patient with chronic plaque psoriasis.

Generalized pustular psoriasis is also known as Von Zumbusch pustular psoriasis. Widespread, acutely painful patches of inflamed skin develop suddenly. Pustules appear within a few hours, then dry and peel within two days.

Generalized pustular psoriasis can make life-threatening demands on the heart and kidneys.

Palomar-plantar pustulosis (PPP) generally appears between the ages of 20 and 60. PPP causes large pustules to form at the base of the thumb or on the sides of the heel. In time, the pustules turn brown and peel. The disease usually becomes much less active for a while after peeling.

Acrodermatitis continua of Hallopeau is a form of PPP characterized by painful, often disabling, lesions on the fingertips or the tips of the toes. The nails may become deformed, and the disease can damage bone in the affected area.

INVERSE PSORIASIS. Inverse psoriasis occurs in the armpits and groin, under the breasts, and in other areas where skin flexes or folds. This disease is characterized by smooth, inflamed lesions and can be debilitating.

ERYTHRODERMIC PSORIASIS. Characterized by severe scaling, itching, and pain that affects most of the body, erythrodermic psoriasis disrupts the body’s chemical balance and can cause severe illness.

This particularly inflammatory form of psoriasis can be the first sign of the disease, but often develops in patients with a history of plaque psoriasis.

PSORIATIC ARTHRITIS. About 10% of patients with psoriasis develop a complication called psoriatic arthritis. This type of arthritis can be slow to develop and mild, or it can develop rapidly. Symptoms of psoriatic arthritis include:
  • joint discomfort, swelling, stiffness, or throbbing
  • swelling in the toes and ankles
  • pain in the digits, lower back, wrists, knees, and ankles
  • eye inflammation

Causes and symptoms

The cause of psoriasis is unknown, but research related to the Human Genome Project is mapping the genetic component of the disease. As of late 2001, accumulated evidence indicates that psoriasis is a multifactorial disorder, which means that it is the end result of a number of different factors.

It appears to be caused by the combined action of multiple disease genes in a single individual that are triggered by irritants in the environment. Factors that increase the risk of developing psoriasis include:
  • blood relatives with psoriasis
  • stress
  • exposure to cold temperatures
  • injury, illness, or infection
  • steroids and other medications
  • mechanical stress (leaning on knees or skin exposure to chemicals, for example)

Trauma and certain bacteria may trigger psoriatic arthritis in patients with psoriasis.


A medical history and physical examination is the basis for a diagnosis of psoriasis. In some cases, a microscopic examination of skin cells is also performed.

Blood tests can distinguish psoriatic arthritis from other types of arthritis.


Psoriasis treatments include:
  • Soaking in warm water and German chamomile (Matricaria recutita) or bathing in warm salt water.
  • Drinking as many as three cups a day of hot tea made with one or a combination of the following herbs: burdock root (Arctium lappa), dandelion (Taraxacum mongolicum) root, Oregon grape root (Mahonia aquifolium), sarsaparilla (Smilax officinalis), and balsam pear (Momardica charantia).
  • Taking two 500-mg capsules of evening primrose oil (Oenothera biennis) a day. Pregnant women should not use evening primrose oil, and patients with liver disease or high cholesterol should use it only under a doctor’s supervision.
  • Eating a diet that includes plenty of fish, turkey, celery (for cleansing the kidneys), parsley, lettuce, lemons (for cleansing the liver), limes, fiber, and fruit and vegetable juices.
  • Eating a diet that eliminates animal products high in saturated and unsaturated fats, such as fried foods, dairy products, and fatty meats, that promote inflammation.
  • Drinking plenty of water (at least eight glasses) each day.
  • Regularly imagining clear, healthy skin.

Other helpful alternative approaches include identifying and eliminating food allergens from the diet; enhancing liver function; augmenting the supply of hydrochloric acid in the stomach; and completing a detoxification program. Constitutional homeopathic treatment, if properly prescribed, can sometimes help resolve psoriasis.

Allopathic treatment

Age, general health, lifestyle, and the severity and location of symptoms influence the type of treatment used to reduce inflammation and decrease the rate at which new skin cells are produced.

Because the course of this disease varies with each individual, doctors must experiment with or combine different treatments to find the most effective therapy for a particular patient.

Mild–moderate psoriasis

Steroid creams and ointments are commonly used to treat mild or moderate psoriasis, and steroids are sometimes injected into the skin of patients with a limited number of lesions.

In mid-1997, the United States Food and Drug Administration (FDA) approved the use of tazarotene (Tazorac) to treat mild-to-moderate plaque psoriasis. This water-based gel has chemical properties similar to Vitamin A.

Brief daily doses of natural sunlight can significantly relieve symptoms. Sunburn, however, has the opposite effect.

Certain moisturizers and bath oils can loosen scales, soften skin, and may eliminate the itch. (Often petroleum-based, coal tar-based, or other greasy ointments are used.)

Adding a cup of oatmeal to a tub of bath water or using Aveeno in the bath can soothe the itch. Dilute, topical salicylic acid (an ingredient in aspirin) can be used to remove dead skin or increase the effectiveness of other therapies.

Moderate psoriasis

Administered under medical supervision, ultraviolet light B (UVB) is used to control psoriasis that covers many areas of the body or that has not responded to other treatment.

Doctors combine UVB treatments with topical medications to treat some patients and sometimes prescribe home phototherapy, in which the patient administers his own UVB treatments.

Photochemotherapy (PUVA) is a medically supervised procedure that combines medication with exposure to ultraviolet light (UVA) to treat localized or widespread psoriasis.

An individual with wide-spread psoriasis that has not responded to treatment may enroll in one of the day treatment programs conducted at special facilities throughout the United States. Psoriasis patients who participate in these intensive sessions are exposed to UVB and given other treatments for six to eight hours a day for two to four weeks.

A newer form of treatment that has several advantages over standard phototherapy is therapy with an excimer laser system. Laser treatment for psoriasis uses a carefully focused beam of ultraviolet light that not only relieves symptoms quickly but also minimizes exposure of healthy skin to the ultraviolet rays.

Severe psoriasis

Methotrexate (MTX) can be given as a pill or as an injection to alleviate symptoms of severe psoriasis or psoriatic arthritis. Patients who take MTX must be carefully monitored by a doctor who checks blood liver enzymes to prevent liver damage.

Psoriatic arthritis can also be treated with nonsteroidal anti-inflammatory drugs (NSAIDs), like acetaminophen (Tylenol) or aspirin. Hot compresses and warm water soaks may also provide some relief for painful joints.

Other medications used to treat severe psoriasis include etrentinate (Tegison) and isotretinoin (Accutane), whose chemical properties are similar to those of Vitamin A.

Most effective in treating pustular or erythrodermic psoriasis, Tegison also relieves some symptoms of plaque psoriasis. Tegison can enhance the effectiveness of UVB or PUVA treatments and reduce the amount of exposure necessary.

Accutane is a less effective psoriasis treatment than Tegison, but can cause many of the same side effects, including nosebleeds, inflammation of the eyes and lips, bone spurs, hair loss, and birth defects.

Tegison is stored in the body for an unknown length of time, and should not be taken by a woman who is pregnant or planning to become pregnant. A woman should use reliable birth control while taking Accutane and for at least one month before and after her course of treatment.

Cyclosporin emulsion (Neoral) is used to treat stubborn cases of severe psoriasis. Cyclosporin is also used to prevent rejection of transplanted organs, and Neoral, approved by the FDA in 1997, should be particularly beneficial to psoriasis patients who are young children or African Americans, or those who have diabetes. The drawback to use of cyclosporin, however, is that it has been implicated in an increased risk of skin cancer for psoriasis patients.

Researchers in Boston reported toward the end of 2001 that psoriasis patients who had been given cyclosporin as part of their treatment developed three times as many squamous cell cancers as those who had not. Patients who had taken cyclosporin for longer than three months were four times as likely to develop skin cancers.

A promising new medication for psoriasis that is in the clinical testing stage as of early 2002 is a drug called Alefacept. Alefacept targets the T-cells that cause psoriasis without suppressing the patient’s immune system. The new drug not only relieves the symptoms of psoriasis more rapidly than current treatments, but patients also remain symptom-free longer.

Other conventional treatments for psoriasis include:
  • Capsaicin (Capsicum frutecens), an ointment that can stop production of the chemical that causes the skin to become inflamed and halts the runaway production of new skin cells. Capsaicin is available without a prescription, but should be used under a doctor’s supervision to prevent burns and skin damage.
  • Hydrocortisone creams, topical ointments containing a form of vitamin D called calcitriol, and coal-tar shampoos and ointments can relieve symptoms but may cause such side effects as folliculitis (inflammation of hair follicles) and heightened risk of skin cancer.

Expected results

Most cases of psoriasis can be managed. However, some people who have psoriasis are so self-conscious and embarrassed about their appearance that they become depressed and withdrawn. The Social Security Administration grants disability benefits to about 400 psoriasis patients each year.


A doctor should be notified if:
  • Psoriasis symptoms appear or reappear after treatment.
  • Pustules erupt on the skin and the patient experiences fatigue, muscle aches, and fever.
  • Unfamiliar, unexplained symptoms appear.