Plaque psoriasis


Psoriasis is a common skin condition that causes skin redness and irritation. Most people with psoriasis have thick, red skin with flaky, silver-white patches called scales.

See also: Guttate psoriasis

Causes, incidence, and risk factors

Psoriasis is very common. Anyone can get it,  but it most commonly begins between ages 15 and 35.

It is not contagious. You cannot spread it to others.

Psoriasis seems to be passed down through families. Doctors think it probably occurs when the body's immune system mistakes healthy cells for dangerous substances. See also: Inflammatory response

Usually, skin cells grow deep in the skin and rise to the surface about once a month. In persons with psoriasis, this process is too fast. Dead skin cells build up on the skin's surface.

The following may trigger an attack of psoriasis or make the condition more difficult to treat:

Bacteria or viral infections, including strep throat and upper respiratory infections

Dry air or dry skin

Injury to the skin, including cuts, burns, and insect bites

Some medicines, including antimalaria drugs, beta-blockers, and lithium


Too little sunlight

Too much sunlight (sunburn)

Too much alcohol

In general, psoriasis may be severe in people who have a weakened immune system. This may include persons who have:


Autoimmune disorders (such as rheumatoid arthritis)

Cancer chemotherapy

Some people with psoriasis may also have arthritis, a condition known as psoriatic arthritis.


Psoriasis can appear suddenly or slowly. Many times, it goes away and then comes back again and again.

Symptoms include:

Irritated, red, flaky patches of skin

Most often seen on the elbows, knees, and middle of the body

Red patches may appear anywhere on the body, including the scalp

The skin may be:


Dry and covered with silver, flaky skin (scales)

Pink-red in color (like the color of salmon)

Raised and thick

Other symptoms may include:

Genital lesions in males

Joint pain or aching

Nail changes, including thick nails, yellow-brown nails, dents in the nail, and nail lifts off from the skin underneath

Severe dandruff on the scalp

Psoriasis may affect any or all parts of the skin. There are five main types of psoriasis:

Erythrodermic -- The skin redness is very intense and covers a large area.

Guttate -- Small, pink-red spots appear on the skin.

Inverse -- Skin redness and irritation occurs in the armpits, groin, and in between overlapping skin.

Plaque -- Thick, red patches of skin are covered by flaky, silver-white scales. This is the most common type of psoriasis.

Pustular -- White blisters are surrounded by red, irritated skin.

Signs and tests

Your doctor or nurse can usually diagnose this condition by looking at your skin.

Sometimes, a skin biopsy is done to rule out other possible conditions. If you have joint pain, your doctor may order x-rays.


The goal of treatment is to control your symptoms and prevent infection.

Three treatment options are available:

Skin lotions, ointments, creams, and shampoos. These are called topical treatments.

Pills or injections that affect the body's immune response, not just the skin. There are called systemic, or body-wide, treatments.

Phototherapy, which uses light to treat psoriasis.


Most of the time, psoriasis is treated with medications that are placed directly on the skin or scalp. This may include:

Cortisone creams and ointments

Creams or ointments that contain coal tar or anthralin

Creams to remove the scaling (usually salicylic acid or lactic acid)

Dandruff shampoos (over-the-counter or prescription)


Prescription medicines containing vitamin D or vitamin A (retinoids)


If you have very severe psoriasis, your doctor will likely recommend medicines that suppress the immune system's faulty response. These medicines include methotrexate or cyclosporine. Retinoids such as acitretin can also be used.

Newer drugs called biologics are used when other treatments do not work. Biologics approved for the treatment of psoriasis include:

Adalimumab (Humira)

Alefacept (Amevive)

Etanercept (Enbrel)

Infliximab (Remicade)



Some people may choose to have phototherapy.

Phototherapy is a medical treatment in which your skin is carefully exposed to ultraviolet light.

Phototherapy may be given alone or after you take a drug that makes the skin sensitive to light.

Phototherapy for psoriasis can be given as ultraviolet A (UVA) or ultraviolet B (UVB) light.


If you have an infection, your doctor will prescribe antibiotics.


Follow these tips at home:

Oatmeal baths may be soothing and may help to loosen scales. You can use over-the-counter oatmeal bath products. Or, you can mix 1 cup of oatmeal into a tub of warm water.

Sunlight may help your symptoms go away. Be careful not to get sunburned.

Relaxation and antistress techniques may be helpful. The link between stress and flares of psoriasis is not well understood, however.

Support Groups

See: Psoriasis support group

Expectations (prognosis)

Psoriasis is a life-long condition that can be controlled with treatment. It may go away for a long time and then return. With appropriate treatment, it usually does not affect your general physical health.




Severe itching

Secondary skin infections

Side effects from medicines used to treat psoriasis

Skin cancer from light therapy

Calling your health care provider

Call your health care provider if you have symptoms of psoriasis or if the skin irritation continues despite treatment.

Tell your doctor if you have joint pain or fever with your psoriasis attacks.

If you have symptoms of arthritis, talk to your dermatologist or rheumatologist.

Go to the emergency room or call the local emergency number (such as 911) if you have a severe outbreak that covers all or most of your body.


There is no known way to prevent psoriasis. Keeping the skin clean and moist and avoiding your specific psoriasis triggers may help reduce the number of flare-ups.

Doctors recommend daily baths or showers for persons with psoriasis. Avoid scrubbing too hard, because this can irritate the skin and trigger an attack.