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Psoriatic Arthritis Causes

The exact cause of psoriatic arthritis isn't fully known, but like psoriasis, it's believed to be a complex interaction between 3 factors:

  • Immune system
  • Genetics
  • Environmental factors

Inflammation Caused by the Immune System

The pain and swelling in your joints is a result of inflammation caused by an abnormal response of your body's immune system. Your immune system mistakenly attacks healthy cells and tissue similar to when fighting off an infection, leading to inflammation in your joints.

Genetics and Environmental Factors

What causes the abnormal response of your immune system isn't entirely clear, but scientists believe that genetics may play a significant role. Many people with PsA have a family history of the disease, and it's been discovered that there are certain genes associated with PsA that may be inherited.

Certain environmental factors, such as an injury or infection, are then believed to "trigger" those inherited PsA genes, causing symptoms of PsA to appear.

Areas PsA Commonly Affects


PsA can cause pain and stiffness in joints on just one side (asymmetric arthritis) or both sides of the body (symmetric arthritis). While PsA can affect any joint in the body, swelling and pain in the fingers and toes is typical. The lower back, wrists, knees, or ankles may also be affected.