What Is Acne?

Acne is the term for a physical change in the skin caused by a disease process in the hair follicles or pores which are blocked and preventing sebum (oil) which is produce by sebaceous glands from draining to the skin surface. It occurs on the face, neck, chest, back, shoulders and even the upper arms.



When that occur a comedo which is a sebaceous follicle plugged with sebum, dead cells from inside the sebaceous follicle, tiny hairs, and sometimes bacteria, is formed, initially as "microcomedone". The picture below is a "microcomedone":



Microcomedones become skin blemishes called comedones--either a whitehead or a blackhead.



Whitehead - When the trapped sebum and bacteria stay below the skin surface, a whitehead is formed.






Blackhead
A blackhead occurs when the trapped sebum and bacteria partially open allowing some of the content to slowly drain to the surface. The "black" color is due to a reaction of the skin's own pigment, melanin, reacting with the oxygen in the air. A blackhead tends to be a stable structure, and can often take a long time to clear.

Neither blackheads nor whiteheads should be squeezed or picked open, unless extracted by a dermatologist under sterile conditions. Tissue injured by squeezing or picking can become infected by staphylococci, streptococci and other skin bacteria.