What does a dandruff shampoo and conditioner do?

If I start to use one, will it take care of the dryness and prevent my scalp from flaking?What does a dandruff shampoo and conditioner do?
My daughter struggles with dryness and dandruff and nothing I could buy in the store helped her. Finally I asked my Dr. about it and he prescribed a dandruff shampoo. She only needed to use it every other day and it cleared her right up. Now she only uses it if she sees signs of dandruff. We have only had to buy one bottle of it. It lasts a long time. I wish I had asked the Dr. long before we purchased tons of different shampoos in the store.What does a dandruff shampoo and conditioner do?
head and shoulders.





and yes it does.