Tip: There is such a thing as too much treatment. If you incorporate a new oil, shampoo, and conditioner in one week, how do you know which one is working? There also might be negative interactions between the products. "You want to allow any change you have incorporated, whether that's a new product or style adjustment, a reasonable amount of time," said Phillips.
For your guy: Kiehl's Scalp Purifying Anti-Dandruff Shampoo ($18)