Bacteria that normally live on the skin also play a role in acne development. The bacteria known as Propionibacterium acnes are responsible for causing acne. These bacteria produce substances that cause inflammation. These substances also make the inflammation worse. Certain hormones called androgens are an additional factor in causing acne.
Androgens are male hormones that are present in both men and women, but are higher in men.
Androgens surge at puberty, which is why teens develop armpit and pubic hair, and why boys develop facial hair and deeper voices. This hormonal surge also contributes to the development of acne in teens. Estrogens, which are the female hormones, actually can help to improve acne in girls. A woman's monthly menstrual cycle is due to changes in the estrogen levels in her body. This is why acne in a female may get better and then get worse as she goes through her monthly cycle.