Study to Test the Effectiveness of a New Treatment for Scalp Psoriasis

Inclusion Criteria: * Male or female of age 18 or older * Patient with a personal history of scalp psoriasis * Patient with treatable lesions * Patient with a TSS score equal or lower than 9. * Patient with a PGA score equal or lower than 5. * Patient with a negative urine pregnancy test at inclusion for women of childbearing potential and using an efficient contraceptive (oral contraceptives, IUD, or tubal ligation) * Patient agreeing to participate to the study and to sign a written informed consent and comply with study requirements. Exclusion Criteria: * Patient treated with topical scalp treatment for scalp psoriasis within two weeks prior to the inclusion in the study (corticoids, retinoids, vitamin D derivatives), * Patient treated with systemic treatment for psoriasis (biologics, methotrexate, cyclosporine, retinoids) within one month prior to the inclusion in the study * Patient taking systemic niacin or multivitamins within past two weeks * Patient who start or modify a treatment with beta-blockers within one month prior to the inclusion in the study * Patient with PEG (Poly Ethylene Glycol) allergy * Pregnant or breast feeding female or female who do not use contraception, * Patient with an history of hypersensitivity to Dovonex/Daivonex * Patient who has participated in a clinical trial within three month prior inclusion, * Patients on Carbamazepine and Primidione (the clearance of Primidione and Carbamazepine may be reduced with the concomitant use of Nicotinamide) * Patient who is under guardianship, or unable to understand the information (for linguistic or mental reason), or unwilling to give her/his informed consent to participate in the study