What is acne? NYC New York NY

Human skin, especially on the face, neck, back, and chest is covered in hundreds of thousands of microscopic hair follicles, often called pores.

For reasons no one completely understands, these follicles sometimes overproduce cells and become blocked. Sebum (oil) which normally drains to the surface gets trapped and bacteria begins to grow.2-11

All acne lesions start out as a microcomedone.1,12-13

Normal follicle
Normal follicle
There are two main types of acne

1. Non-inflammatory acne
Microcomedones can spontaneously become unplugged and heal or they become non-inflamed skin blemishes called comedones--either a whitehead or a blackhead:12-13

When the trapped sebum and bacteria stay below the skin surface, a whitehead is formed. Whiteheads may show up as tiny white spots or they may be so small that they are invisible to the naked eye.1,13
A blackhead occurs when the pore opens to the surface and the sebum, which contains the skin pigment melanin, oxidizes and turns a brown/black color. It is not dirt and can not be washed away. Blackheads can last for a long time because the contents very slowly drain to the surface.1,13
2. Inflammatory acne
A blackhead or whitehead can release its contents to the surface and heal or the follicle wall can rupture and inflammatory acne can ensue. This rupture can be caused by random occurrence or by picking or touching the skin. This is why it is important to leave acne prone skin relatively untouched.1,12-13

A papule occurs when there is a break in the follicular wall. White blood cells rush in and the pore becomes inflamed.13
A pustule forms several days later when white blood cells make their way to the surface of the skin. This is what people usually refer to as a "zit" or a "pimple."13
A papule or pustule can completely collapse or explode, severely inflaming the surrounding skin and may engulf neighboring follicles. These lesions are called cysts or nodules:1,13

Sometimes a severe inflammatory reaction can result in very large pus filled lesions.1,13
When a follicle breaks along the bottom, total collapse can occur, causing a large, inflamed bump that can be sore to the touch.13