Topical corticosteroids and vitamin D analogs can be combined with other topical, systemic, and biological agents. The effect of methotrexate can be enhanced with ultraviolet B (UVB) or psoralen ultraviolet A (PUVA). When a biological agent remains insufficient, the first agent to be added to the treatment is methotrexate. The use of acitretin in combination with phototherapy (both UVB and PUVA) has a synergistic effect. A UVB therapy may be combined with topical tar and anthralin as well as with etanercept and adalimumab, which are anti-tumor necrosis factor-alpha therapies.