Why and how psoriasis and psoriatic arthritis are connected isn’t completely clear. What is known is that both conditions are autoiummune. This means they are caused by the body’s own immune system turning itself on automatically as if it is fighting a foreign infection when there is none there. The body’s response to the attack is inflammation or swelling, which results in the red itchy and scaly patches of psoriasis and the joint swelling and pain of PsA.

Up to 30% of people with psoriasis will also develop PsA, though PsA usually doesn’t occur for years after the start of psoriasis. There is no clear link between the severity of psoriasis symptoms a person has and the severity of the symptoms they might have if they develop PsA. However, people whose psoriasis involves scalp lesions, mis-shapen, damaged or infected nails or inflammation of the skin in the buttock area may be at increased risk.

While psoriasis most commonly comes first and usually about ten years before PsA, in some cases, psoriasis and PsA appear at the same time. However, in about 15% of cases, symptoms of arthritis are noticed before psoriasis appears.


A dermatologist will likely discuss the risk of PsA with their psoriasis patients and if certain signs or symptoms arise, they may refer a patient to a rheumatologist for further examination. Keeping an eye out for swollen, tender and painful joints or tendons that might come on suddenly or grow over time, particularly if in more than one place on your body, could help you spot the early signs of PsA. Besides joint pain and swelling, symptoms like fatigue, reduced range of motion, morning stiffness and tiredness are also potential signs of PsA.


Other things to watch for are changes to the fingernails and toenails. It’s not uncommon to see nails separating from the nail bed or becoming pitted similar to a fungal infection. About 40 to 45% of people with psoriasis, who don’t have arthritis, are likely to have nail lesions. Almost 90% of people with PsA will have evidence of the disease in their nails.

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