The stuff inside a blackhead might look like dirt, but it isn’t. Both whiteheads and blackheads form when a pore is blocked by dead skin cells, sebum and bacteria. The difference is that whiteheads exist completely under the surface of the skin, while blackheads are open at the top and exposed to the air. The air oxidizes the melanin in the dead skin cells, turning it black. Your best weapon for getting rid of and preventing blackheads is salicylic acid, which will break up those plugs and unclog the pores.