Causes and Triggers
The exact cause of psoriasis is not fully understood, although it appears to be the result of a problem with the immune system where white blood cells called T cells, which are normally activated to fight infections, become activated against healthy skin cells instead.
As part of this process the T cells release chemicals called cytokines which stimulate inflammation (redness) and accelerates the growth of skin cellsxii.
The skin cells then build up and cause the typical thickened, scaly patches of psoriasis.
It is not clear what causes the immune system to become activated against healthy skin cells. Psoriasis can run in families so it may have a genetic cause. In fact, around a third of people with psoriasis have a relative who also suffers from the conditionxii.
Although psoriasis plaques may look infected they aren’t, and they are not contagious. Other people cannot ‘catch it’ by touching the affected areas of your skin.
Triggers are factors that lead to a worsening or reappearance of skin symptoms in someone with psoriasis. Triggers are not universal. Triggers that may cause one person’s psoriasis to become active may not affect another. Common triggers areviii:
Stress: Studies have shown that stress can trigger psoriasis or aggravate it.
Injury to the skin: People with psoriasis often notice new lesions 10 to 14 days after the skin is cut, scratched or severely sunburned.
Infection: Some infections, such as a sore throat, may trigger a certain type of psoriasis, known as guttate psoriasis. Inverse psoriasis is often aggravated by thrush.
Medication: Some medications have been found to trigger psoriasis or flare-ups in some people. Examples include anti-malarial drugs; beta-blockers used to treat high blood pressure; heart medication; corticosteroids used to treat psoriasis; Indomethacin used to treat arthritis and other inflammatory conditions; and Lithium used to treat manic depression.
If you think a medication may be affecting your psoriasis, talk to your doctor, nurse practitioner or pharmacist before making any changes.
See Living with Psoriasis for more tips on recognising your triggers and how to deal with them.