The cause of psoriasis is unclear. Signals from the immune system may cause the change in skin cells. The cells grow faster than they can be shed and pile up on the skin's surface. This pile up causes the patches.

Risk Factors

Psoriasis usually develops in people under 40 years old. Things that raise the risk are:

  • Family history of psoriasis
  • Cold climates
  • Certain bacterial infections
  • Certain medicines such as beta blockers, tumor necrosis factor-alpha inhibitors, and lithium
  • Smoking
  • Skin injury
  • Weakened immune system



Symptoms of psoriasis are red, thickened, and rough patches on the skin. The patches can happen anywhere on the skin. They are most common on the scalp, elbows, knees, palms, and soles. Other symptoms include:

  • Silvery white scales over the patches
  • Pitted or dented fingernails and/or toenails
  • Red sores or rashes in folds of skin
  • Joint pain (psoriatic arthritis)

The skin may also be sore, burning, or itchy. This depends on the type of psoriasis.

The rashes and lesions may come and go.


The doctor will ask about symptoms and past health. A physical exam will be done. It will focus on the skin and nails. The doctor may make a diagnosis based on how the skin looks. A skin biopsy may confirm the diagnosis.



Treatment will be based on how severe it is and how much skin is involved. Options may include:

Medicines applied to the skin, such as:

  • Corticosteroid creams and ointments (most common treatment)
  • Man-made forms of vitamin D
  • Retinoids
  • Coal tar preparations
  • Bath solutions and moisturizers
  • Tacrolimus and pimecrolimus (especially for inverse psoriasis)
  • Bimekizumab for plaque psoriasis

Photo (Light) Therapy

Psoriasis over large areas can be hard to treat with lotions or creams. Phototherapy may be used instead. It uses medicine and a special light applied to the skin. This treatment makes the body more sensitive to light. It requires many treatments.

Systemic Medicines

More severe psoriasis may need medicine that affects more of the body. Options may be medicines that lower the immune system to:

  • Slow the turnover of cells
  • Ease inflammation
  • Prevention

    There are no guidelines to prevent psoriasis. People who have the condition may be able to reduce flare-ups by avoiding:

  • Trauma to the skin
  • Infections
  • Cold, dry temperatures
  • This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

    Edits to original content made by Denver Health.