What is it? 

Acne is caused by overactive oil glands in the skin and a buildup of oil, dead skin cells, and bacteria, which leads to inflammation (swelling and redness) in the pores. Oil glands get stimulated when hormones become active during puberty. That’s why people are likely to get acne in their teens.

-An estimated 85% of teens get acne, usually starting at age 11 for girls and a couple of years later for boys. Acne can last through the teen years and into the early 20s. Some older adults may continue to be bothered by it. Many women note that it worsens just before menstruation and disappears during pregnancy.