The skin has tiny holes called pores that can become blocked by oil, dirt, bacteria, and dead skin cells. When this happens, it develops a pimple or zit. If this condition affects the skin frequently enough, it can cause acne.
Each pore of the skin is the opening to a follicle. The follicle is made up of two hairs and a sebaceous (oil) gland. Sebum (oil) is produced by the oil gland and travels up the hair to the skin. The sebum keeps the skin lubricated and soft.
One or more problems in this lubrication process can cause acne. It can occur when:
Too much oil is produced by your follicles. Dead skin cells accumulate in your pores. Bacteria build up in your pores.