I would look for trial sizes, some of these get expensive. My oldest DS has dandruff and when we found out, we started checking out shampoos. We started with Neutrogena T something with tar in it, with little effect. We then went to Selsun Blue, I got a phone call from the school nurse that he was in there and that his scalp was itching so bad that it was red. He was checked for lice, didn't find any but the red scalp was very evident. We then tried Head & Shoulders, this works for him. I've never heard of the Listerine treatment, I would be willing to try if he didn't already have a bad reaction while trying to treat this. I guess we stick with what works for him.