http://articles.mercola.com/sites/articles/archive/2009/06/30/Whats-Your-Best-Advice-for-Dandruff-Heres-Mine.aspx
Two shampoos that work well are Selsun Blue and Head & Shoulders. I’ve used both in the past with good results.
Selsun Blue contains a form of selenium sulfide, whereas Head & Shoulders has zinc as the active ingredient. Both are toxic to the fungus.
The most effective way to use them is to lather your scalp with the shampoo at night before you go to bed, and keep it on overnight. Wear a shower cap so you don’t ruin your pillow case. Then wash it off in the morning.
If needed you can repeat this treatment once a week, but typically you’ll only need one or two treatments to permanently eliminate the fungus. This seems to be a much safer alternative to using the shampoo daily for many years.