The process begins when excess oil is produced by the sebaceous glands in the skin. This oil, along with dead skin cells, can block the opening of the hair follicle, creating a plug known as a comedo. When this plug is open at the surface of the skin, it’s called a blackhead. If the plug is closed and not exposed to air, it’s called a whitehead.
Blackheads, also known as open comedones, are a type of acne lesion that forms when hair follicles become clogged with oil, dead skin cells, and other debris. They are a mild form of acne and are characterized by small, dark spots on the skin. Despite their name, blackheads are not caused by dirt; the dark appearance is due to the oxidation of the oil (sebum) in the clogged hair follicle.