There is a Selsun product that is made especially for dandruff which is good however my dandruff was caused by Psoriasis so these treatments would not work on this.
I always thought dandruff was caused by dry scalp.
Saw a good thing on TV to pre-poo your hair -coconut oi, mashed banana -mix and leave in hair 15 minutes before showering and washing out -supposed to put the moisture back in your hair that shampoo strips -still use conditioner but this apparently makes hair shiny and healthy and should therefore alleviate dry skin causing dandruff.
If it's not psoriasis related, mix apple cider vinegar and water in equal amounts and use in place of conditioner after you've shampooed. Leave it in the hair for 10-15 minutes and then rinse out. The smell of the vinegar will go away once dry.
Don't try this on psoriasis or a scalp with a scratch on it or it will hurt.
There are several ways. #1 is to shampoo your hair daily, dandruff comes from excessive oils in the hair. #2 Switch to a zinc pyrithione based shampoo. #3 you can also use tar shampoo (make sure you rinse your hair with lemon to get it out) #4. You can always use lemons
Take peels of 3-4 lemons and boil them in 4-5 cups of water for approximately 15-20 minutes.
Once it cools down, use this solution to wash your hair, at least once a week.