Female, 44, scalp psoriasis took antibiotics and prescribed scalp oil but is nizoral shampoo good for avoiding this infection again (besides resisting need to scratch)?

Nizoral shampoo is used to treat dandruff primarily. Daily shampoos otherwise aren't necessary in treatment of scalp psoriasis. In my experience, if you have the thick patches you're better off being treated by a dermatologist to get the best care&follow-up. Daily treatments are often needed and include medicated shampoos,actual medication applied to the scalp,injections, newer biologic medication

Antibiotics, scalp oil and/or antifungals are not agents used in the treatment of psoriasis unless complicated with skin infection. Best would be to see your dermatologist in follow up to clarify diagnosis and get proper treatment as needed.