Both blackheads and whiteheads occur as a result of a clogged hair follicle (comedo). What makes them different, however, is the type of comedo and what causes it to be clogged.
These are known as ‘open comedones’ because, although the follicle is blocked, the blockage is open to the air. They occur as a result of excess facial oil and sebum production, dry skin and dirt – which cause the follicle to become blocked – while oxidisation makes them follicle appear brown or black. When a blackhead extraction facial is performed, all oil, sebum, dry skin and dirt is gently squeezed from the follicle.
Whiteheads are known as ‘closed comedones’, as the blocked follicle is closed to the air. Like blackheads, whiteheads are caused by excess facial oil and sebum production, dry skin and dirt. The difference between the two lies in the presence of bacteria that result in whiteheads. Propionibacterium Acnes bacteria multiply in the clogged pore causing redness, infection and the production of pus. As the clogged follicle is closed to the air, the pus stays underneath the skin.