The main event in classic Head & Shoulders is pyrithione zinc. That’s a mouthful, so let’s call it P.Z. for short. This is the bouncer at the club of your scalp, kicking out the party-crashing fungus that causes dandruff. Yes, you have a fungus living on your head right now. Welcome to the human race—we’re all a little moldy up there.
P.Z. works by messing with the fungus’s cell membrane, basically giving it a microscopic eviction notice. It’s not a poison; it’s more like a frenemy that forces the fungus to behave. And because it’s a solid powder, it sticks around on your scalp long after you’ve rinsed. It’s the house guest who refuses to leave, but in a good way.
