Plaque Psoriasis

Psoriasis is a common skin inflammation (irritation and swelling) characterized by frequent episodes of redness; itching; and thick, dry, silvery scales on the skin.

Alternative Names
Plaque psoriasis

Causes, incidence, and risk factors
Psoriasis is a very common condition, with approximately 3 million Americans affected. It can appear suddenly or gradually. In many cases, psoriasis goes away and then flares up again repeatedly over time. The disorder may affect people of any age, but it most commonly begins between ages 15 and 35.

Psoriasis seems to be an inherited disorder, probably related to an inflammatory response in which the immune system accidentally targets the body’s own cells. Evidence of the condition is most commonly seen on the trunk, elbows, knees, scalp, skin folds, or fingernails, but it may affect any or all parts of the skin.

Normally, it takes about a month for new skin cells to move up from the lower layers to the surface. In psoriasis, this process takes only a few days, resulting in a build-up of dead skin cells and formation of thick scales.

Psoriasis may be aggravated by injury or irritation (such as cuts, burns, rashes, insect bites). It may be severe in immunosuppressed people (like those with AIDS or undergoing chemotherapy for cancer), or those who have other autoimmune disorders (such as rheumatoid arthritis).

Medications, viral or bacterial infections, excessive alcohol consumption, obesity, lack of sunlight, sunburn, stress, general poor health, cold climate, and frequent friction on the skin are also associated with psoriasis flare-ups. The condition is not contagious.


  • Skin patches
    • Dry or red
      • Usually covered with silvery scales      
      • Raised patches of skin      
      • Accompanied by red borders      
      • May crack and become painful      
      • Usually discrete, demarcated patches      
      • Usually located on the elbows, knees, trunk, scalp, hands or nails


    • Skin lesions, including pustules, cracking of skin, skin redness or inflammation

    • Itching

    • Small scaling dots on the skin (especially in children)

    • Joint pain or aching, which may be associated with a special type of arthritis (psoriatic arthritis)

    Additional symptoms that may be associated with this disease:

    • Nail abnormalities  
    • Genital lesions in males  
    • Eye burning, itching, and discharge  
    • Increased tearing

    Signs and tests
    The diagnosis is usually based on the appearance of the skin.

    • A skin biopsy, or scraping and culture of skin patches, may be needed to rule out other disorders.  
    • An x-ray may be used to check for psoriatic arthritis if joint pain is present and persistent.

    Treatment is focused on control of the symptoms and prevention of secondary infections. It varies with the extent and severity of the disorder. Severe or resistant cases may require intensive treatment.

    Psoriasis lesions that cover all or most of the body are an emergency symptom that require hospitalization. The disorder may be acutely painful. The body loses vast quantities of fluid and is susceptible to severe secondary infections that can become systemic, involve internal organs and even progress to septic shock and death. Treatment includes analgesics, sedation, intravenous fluids, and antibiotics.

    Mild cases are usually treated at home. Topical medications include:

    • Prescription or nonprescription dandruff shampoos  
    • Shampoos or lotions that contain coal tar  
    • Cortisone or other corticosteroids  
    • Lubricants  
    • Antifungal medications  
    • Antibiotics  
    • Phenol  
    • Sodium chloride  
    • Other ingredients

    Oral or injected immunosuppressive medications (such as corticosteroids or methotrexate) may be prescribed, but only in very severe cases. Other medications may include retinoids or cyclosporine.

    Other treatments may include moderate exposure to sunlight or phototherapy. The skin is sensitized by the application of coal tar ointment or by taking oral psoralens (a medication that causes the skin to become sensitive to light). The person is then exposed to ultraviolet light. Avoid sunburn, which can worsen the condition.

    Psoriatic arthritis, which occurs in a very small percentage of patients with psoriasis, may be treated with non-steroidal analgesics in much the same way as normal arthritis.

    Maintain good general health to reduce the risk of flare-ups. Obtain adequate rest and exercise, eat a well-balanced diet and avoid stress (see stress management). Treat respiratory and other infections promptly.

    Maintain good skin hygiene to prevent secondary infections. Daily baths or showers are recommended. Avoid harsh scrubbing, which can irritate the skin and cause new outbreaks.

    Oatmeal baths may be soothing and may help to loosen scales. Commercial preparations may be used, or mix one cup of oatmeal into a tub of warm water.

    Support Groups
    If having psoriasis is causing significant stress, consider joining a psoriasis support group where members share common experiences and problems.

    Expectations (prognosis)
    Psoriasis is a chronic, lifelong condition that can be controlled with treatment. It usually does not adversely affect general health, unless it is neglected or occurs in the elderly or very young.


    • Complications that result from the treatment itself  
    • Secondary skin infections which spread to internal organs

    Calling your health care provider
    Call for an appointment with your health care provider if symptoms indicate psoriasis. Call for an appointment if psoriasis recurs frequently despite treatment.

    Go to the emergency room or call the local emergency number (such as 911) if there is a severe outbreak which covers all or most of the body.

    Also, seek medical attention if pustules, fever, muscle aches, fatigue or other new or unexplained symptoms develop.

    None is known. Keep flare-ups to a minimum by avoiding anything that aggravates your psoriasis.

    Johns Hopkins patient information

    Last revised:

    Diseases and Conditions Center

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    All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.