Seborrheic dermatitis on my scalp for two years

I have been dealing with seborrheic dermatitis on my scalp for two years, and to try to get it under control, Im going to use a shampoo with selenium sulfide and complement it with another one that contains zinc pyrithione. My hair is already quite dry to begin with, so how can I hydrate it properly and prevent these two active ingredients from drying it out even more?