Causes and exacerbating factors of psoriasis

Psoriasis is strongly familial; it is polygenically inherited. In many patients, no specific trigger is identified. Many common drugs (eg angiotensin converting enzyme inhibitors [ACEIs], beta blockers, nonsteroidal anti-inflammatory drugs [NSAIDs]) have been reported to trigger or exacerbate psoriasis. Occasionally, psoriasis is triggered and exacerbated by infections (eg streptococcal, viral [including HIV]), skin trauma (eg Köbner phenomenon) or stress. Alcohol can also exacerbate psoriasis.

Sunburn, metabolic factors (eg calcium deficiency) and hormonal factors (eg during pregnancy, postpartum) can cause flares of psoriasis. Severe flares (including pustular psoriasis) can be caused by lithium, hydroxychloroquine, interferon alfa and granulocyte-macrophage colony-stimulating factor (GM-CSF). Severe flares can also be caused by withdrawing systemic or potent topical corticosteroids (used for treating psoriasis or other co-existing conditions).