Psoriatic arthritis (PsA) is a type of arthritis that is associated with a skin condition known as psoriasis. Psoriasis tends to appear first before the onset of arthritis, though in a small number of people, the joint disease can appear before the psoriasis.

Psoriasis is a long-term skin condition that causes a scaly skin rash. Up to 30% of people with psoriasis will get PsA. The main symptoms of PsA are joint pain, swelling, stiffness, and damage. See "Symptoms of PsA" to learn more about other PsA symptoms.

PsA is considered an inflammatory disease, which means that it can cause joint inflammation and pain. Other examples of inflammatory diseases are rheumatoid arthritis and ankylosing spondylitis.

PsA is also an autoimmune disease, which means that the body’s immune system attacks healthy cells and tissues by mistake. In the case of PsA, cells and tissues of healthy joints and skin are attacked by your own immune system, causing inflammation.

Men and women are equally likely to get PsA. It usually affects people 20 to 50 years of age, but it may strike at any age. PsA and psoriasis tend to run in families. If your parent had psoriasis or PsA, you are more likely to have it, too. You are also more likely to get PsA if you have psoriasis of the nails.

There are 5 subtypes of PsA:

  • Polyarticular, symmetric arthritis is very much like rheumatoid arthritis but with less severe symptoms. It usually affects the same joints on both sides of the body.
  • Oligoarticular, asymmetric arthritis does not occur on the same joints on both sides of the body and can affect a few or many joints.
  • Distal interphalangeal joint predominant usually involves the furthest joint of the fingers and toes and usually nail changes are apparent.
  • Spondylitis predominant involves the spinal column, causing stiffness of the neck, lower back, or spinal joints. It is not the same as ankylosing spondylitis.
  • Arthritis mutilans usually affects the small joints of the hands and feet and can cause severe deformities.

These classifications are used but experts recognize that there is a lot of overlap between these subtypes of PsA. One person may have a mix of several subtypes.

The exact cause of psoriatic arthritis is not known. Psoriatic arthritis can have a major impact on your quality of life. But with proper treatment, you can get back to normal living. You can take control of this disease. Talk to your doctor about how to build your own treatment plan.