Methods and apparatuses for phototherapy to treat skin disorders. In particular, described herein are phototherapy dressings for use with phototherapy UV light applicators (sources) to treat skin disorders such as psoriasis. The dressings described herein may include a support body onto which a medicament formed of a hydrogel and coal tar and/or coal tar extract is held. The dressing may be configured so that at least half (50%) of the UV light within a therapeutic range of wavelengths is through the dressing including the medicament to the patients skin. The dressings may be adapted for use in conjunction with a phototherapy UV light sources.