This study will determine if combination of topical calcipotriol and nicotinamide is more effective than calcipotriol alone in treatment of psoriasis.

Current treatment strategies of psoriasis are not completely satisfactorily. By inhibiting inflammatory cytokines, nicotinamide may enhance the effects of current topical treatments. Preliminary studies have shown that nicotinamide, which is a vitamin B derivative, is effective in the treatment of psoriasis. According to lack of data, we will investigate the beneficial effects of adding nicotinamide to calcipotriol for patients with mild to moderate psoriasis.

Inclusion Criteria:

• Men and women of 18 to 65 years old,
• Mild to moderate psoriasis; patients must have had less than 15% of the involved body surface, symmetrical plaques (bilateral lesions) or two plaques at least 5 cm apart on the same side of the body with plaque size greater than 2 × 2 cm, but smaller than 15 × 15 cm.
• Willingness to participate

Exclusion Criteria:

• Those who used any medication or niacin and multi-vitamins two weeks, or anti-psoriatic systemic drugs or beta-blockers one month prior to the study,
• Pregnant women,
• Those with the history of renal, hematologic, liver and major psychiatric diseases,
• Those with only scalp, nail, flexural, palmoplantar, or pustular psoriasis.