Phototherapy in the perspective of the chronicity of psoriasis

Abstract According to the guidelines for the treatment of psoriasis, phototherapy is given in courses of UVB exposure starting at 50–70% of the minimal erythema dose, MED , with subsequently incremental dosages, but keeping erythemal skin reactions to a minimum by restraining the dosages when necessary. In this review, this classical principle of short‐term near erythematogenic UVB therapy without further UVB maintenance therapy is challenged as it is evidently not optimal for psoriasis as a chronic condition. There is old experimental evidence supplemented with growing knowledge on the mode of action of phototherapy and more recent data on low‐level UVB regimens as maintenance therapy that should urge us to revisit our guidelines on phototherapy to address psoriasis for what it is: a chronic condition.