Blackheads are the result of hair follicles being blocked by skin cells and a material called sebum, which is naturally secreted by the sebaceous glands. Sebum is excreted in much larger numbers as kids reach adolescence, accounting for red colored pimples, blackheads and whiteheads. These blockages are very similar to whiteheads, but the main difference lies in the fact that the follicles involved are larger and remain open.
When an open pore becomes blocked with dead skin cells and sebum, this material is exposed to air and begins to oxidize. This causes the material to discolor and turn black, resulting in blackheads. Whiteheads, on the other hand, are covered by a tiny amount of skin that prevents this oxidation, so they remain white in color.
Both blackheads and whiteheads are also called comedones, which are essentially plugs of the hair follicle. They are also called open comedones closed comedones, respectively. They tend to be most prevalent on the skin of the face, neck, and chest, though technically any place where one has hair follicles can yield these blemishes.
Using a good exfoliant, which helps to clean dead skin material out of pores, can often reduce number of blackheads. Also, an astringent may help reduce oil excreted by the pores, which tends to block skin material and form these annoying plugs. Most dermatologists recommend having blockages removed professionally, since improper removal can lead to scarring of the skin. In time, however, most people can remove them merely through use of daily exfoliation and daily application of astringent.
As with all pimples, some blackheads are stubborn, and may not respond to over-the-counter medications or treatments. In these cases, dermatologists can prescribe medications that help slough off dead skin so that fewer plugs form. Teens and adults who have a few blackheads are certainly not alone. About 85% of teens suffer from one form of acne or another.