Environmental factors and psoriasis.

Psoriasis is a chronic relapsing disease characterized by variable clinical features. Several factors may exacerbate its manifestations, or even trigger the disease, such as traumatic injury to the skin, physical and psychological stress, cold weather, excessive alcohol intake, and drugs such as lithium and Beta-blockers. We describe the most common features of psoriasis and the exogenous factors that may induce, trigger or exacerbate the disease.