We do know that the sebaceous glands secrete an oil that changes to a solid white substance called sebum. This travels to the opening of a hair follicle and erupts on the skins surface. This process may be due to an infection of these glands or to excessive amounts of male hormones called androgens.
Blackheads appear when sebum mixes with skin pigments in plugged pores.
They are a mixture of sebum and skin scales that have closed off a hair follicle. Some teenagers find this condition so distressing that they can develop emotional problems. Three out of four teenagers have acne and about 80 percent of all teenagers will develop it. If you have acne you have a lot of company. Most teens who develop acne have the milder form, called non- inflammatory acne.