Stubborn and extensive dermatoses, such as psoriasis vulgaris or atopic dermatitis (eczema), are indications for phototherapeutic methods. These include UVB phototherapy, UVA photochemotherapy (PUVA), UVA irradiation following prior photosensitization, UVA, treatment and combination treatments. Phototherapy is contraindicated in the case of light-induced dermatoses. Caution must also be exercised in patients receiving photosensitizing medications. When establishing the indication, consideration must be given to the treatment-related increased risk of developing skin cancer. The patient must also be informed of such undesired potential side effects as burns and premature aging of the skin.