How does skin oil get blocked?

Skin oil, or sebum, is produced by glands connected to hair follicles. It flows up and out the opening onto the skin surface. It can mix with dead skin cells like a glue and the combination and prevent more sebum from flowing out. To learn more about sebum, watch the animation.

The oil in your skin is called sebum. Your body makes more sebum when your hormones surge. Elevated hormones stimulate the sebaceous glands, which are attached to hair follicles. These glands then produce greater amounts of sebum. An acne lesion or pimple occurs when a hair follicle becomes blocked with sebum and dead cells.