I have been struggling with seborrheic dermatitis since my teenage years (I'm 51 now). In my early twenties, a dermatologist recommended Z Plus to me. This was the best recommendation ever. None of the usual over the counter products worked well for me; either they would not resolve the dandruff issue, or if they did, my hair would be destroyed. Z-Plus walks that fine line of dandruff and itch control, but does not damage your hair. I use it daily when having an issue, and every second or third day once things are under control. Since I have short hair, not much of the product is needed, either, so one bottle can last me 6-8 months. Very highly recommended. (By the way - I'm not sure why, but this product is better than other OTC products that have the same active ingredient - zinc pyrithione. Trust me - I've done MANY comparisons over the decades. This stuff is THE BEST). Note to Dormer: Please NEVER discontinue this product, and if you do - LET ME KNOW IN ADVANCE so I can stock up! Cheers!