Causes.Acne occurs when tiny holes on the surface of the skin become clogged. These holes are called pores.Each pore opens to a follicle. A follicle contains a hair and an oil gland. The oil released by the gland helps remove old skin cells and keeps your skin soft.The glands can become blocked with a mixture of oil and skin cells. The blockage is called a plug or comedone. If the top of the plug is white, it is called a whitehead. It is called a blackhead if the top of the plug is dark.If bacteria become trapped in the plug, the body’s immune system may react to it, causing pimples.Acne that is deep in your skin can cause hard, painful cysts. This is called nodulocystic acne.We’ve all got these tiny openings in our skin for releasing sweat and oil,but for some people, they can be more temperamental than others.Or, rather, clogged pores happen more often to some of us.Acne is most common in teenagers, but anyone can get acne, even babies. The problem tends to run in families.