Psoriatic Arthritis

What is psoriatic arthritis?

Psoriatic arthritis (PsA) is an autoimmune disease that primarily attacks the joints.

It occurs in people who have psoriasis, a related autoimmune disease. In autoimmune disease the immune system does not work as it should. Normally, the immune system protects the body from infection, but in autoimmune disease it attacks the body instead.

In PsA the joints are attacked, causing stiffness and pain.

Who is affected by psoriatic arthritis?

Approximately 20–40% of people with psoriasis will develop PsA. It usually appears within 10 years of psoriasis being diagnosed, although some people may experience problems with their joints before they notice any symptoms affecting their skin.

The exact amount of people with PsA is unknown, but it is believed to affect 1% of the population worldwide. Men and women are equally likely to have this condition, which usually manifests between the 30 and 50 years of age.1,2

What are the symptoms of psoriatic arthritis?

PsA symptoms can vary from person to person. There may be times when the symptoms get better, and also periods when the condition worsens (known as flares). These can be difficult to predict, and patients suffering with flares may need medication when these relapses occur.

PsA is characterized by the combination of different arthritic and psoriatic symptoms. About 85% of patients have skin alterations before joint disease.3 Patients with psoriasis of the nails are more likely to develop PsA.4,5 PsA can develop in a joint after an injury and may mimic a cartilage tear. Muscle or joint pain can occur without swelling. Tendonitis and bursitis may also occur. PsA can also cause swelling of fingers and toes, known as dactylitis.

These symptoms can affect any joint in the body, especially in the hands, feet, knees, neck, spine and elbows.

Additional information

You can find additional information about PsA by following these links:

NHS Choices:

National Psoriasis Association:

Psoriasis and Psoriatic Arthritis Alliance:

1. Mease PJ, Armstrong AW. Drugs. 2014; 74:423–441.
2. Gladman DD et al. Ann Rheum Dis. 2005; 64(Suppl II):ii14–ii17.
3. PsA. Available from:
4. Azevedo VF, Buiar PG. Ann Bras Dematol. 2013;88(2):233-236.
5. Langley RGB, et al. Ann Rheum Dis. 2005;64(Suppl II):ii18-ii23.