People have their pet theories of what causes acne. Many of these notions have nothing to do with the facts. The causes of acne are not as simple as people often think they are. These causes are steeped in science.
The problem of acne starts with the hormone androgen. It is a male hormone that increases during puberty in both young women and young men. There are other times that androgen is in more plentiful supply than usual, as well. There are many times that women have acne due to changed hormone production.
The androgen stimulates the sebaceous glands. These are ducts in the skin that are right next to the hair follicles. They produce a substance called sebum. Sebum is an oily substance that serves the purpose of keeping the skin moist and smooth when all is going well. It also makes the skin more waterproof.