If a follicle is plugged, the bacteria grow rapidly inside and turn the trapped sebum into a very irritating substance. Too much sebum Hormone changes often cause certain glands to produce too much sebum. If sticky cells already block the follicles and the excess sebum has no way to escape, the follicles swell and sometimes even burst. Normal skin without acne Human skin normally secretes oil through the sebaceous gland that is connected to a hair-containing canal called a follicle. When the sebaceous gland is unable to effectively release the necessary oils to the skin due to blockage, pores can form blackheads, whiteheads or rupture and develop pimples.
Most people have or have had all of the different forms of acne.
The following is a description of the most common forms. Whiteheads When plugged follicles continue to produce sebum and there's no way for it to escape, the follicle swells and makes a bump on the skin surface. When the sebum forces the plug to the surface of the skin so that the dark tip may be seen, it is called a blackhead or open comedo. Its dark color is caused by increased skin pigment. It is not dirt and cannot be scrubbed away.