Common causes and triggers
While the exact cause of psoriasis is still unknown, genetic and environmental factors seem to play an important role.
Research suggests that the chances of inheriting psoriasis are 10% in an individual with one affected parent, increasing to 50% in someone with two affected parents. However, not everyone who inherits genes for psoriasis will develop the condition. Internal or external factors, called psoriasis ‘triggers’, can also contribute to the development of psoriasis or a flare-up of plaques.
Triggers are different for each person – what sets off psoriasis in one individual may not have any affect in another.
External factors include injuries to the skin, such as sunburn, vaccinations and scratches. This reaction to trauma is called the “Koebner phenomenon’, named after a doctor in the 19th century who recognised that he had developed new psoriasis plaques in areas where he was bitten by his horse.
Other skin injury and skin conditions known to trigger psoriasis include: shaving, bites, bruising, friction or chafing, acupuncture, chemical irritation or adhesive tape on the skin, tattoos, boils, dermatitis, blisters, vitiligo and scabies.
Internal factors include emotional stress and certain medications – such as lithium, beta blockers, corticosteroids and anti-malaria medication. Some infections, particularly bacterial streptococcal infection – can also be a trigger of psoriasis.
Triggers are different for each person – what sets off psoriasis in one individual may not have any affect in another. To find out what is triggering your flare-ups, the best thing to do is to keep track of your symptoms in-relation to things going on in your life and to talk your condition through with your doctor. He or she will be experienced in identifying potential psoriasis triggers and can help you narrow down what may be affecting you.