Acne appears when sebaceous glands within the hair follicles (pores) of the skin become clogged, because emission happens faster than the oil and skin cells can leave the follicle. The plug causes the follicle to bulge (causing whiteheads), and the tip of the plug may darken (causing blackheads). If the plug causes the wall of the follicle to break, the oil, dead skin cells, and microbes found commonly on the surface of the skin can penetrate the skin and create small infected areas known as pustules (also known as pimples or "zits").

The actual pimple is usually the result of microbes entering an open skin pore causing the body to respond with millions of white cells to eliminate the invaders. As the white cells fight and die they create an inflamed area that turns red (pimple) which over time evolves into an even greater mass of dead cells that can form a pus pocket (white head).

Also, open pores can also be blocked with dried oils, external elements or just facial dirt that form what is usually known as a black head. Salt from sweat is another cause of many facial break outs when it dries and blocks pores.

Cysts appear when the infection affects the deeper layers of the skin. A sebaceous cyst appears when the sebaceous gland continues to produce oil. Instead of breaking the follicle wall, the follicle continues to grow and form a soft, pliable lump (called a cyst) beneath the skin. The cyst is commonly not painful or discolored unless it becomes infected.

Acne Scar Causes

Acne scars appear when spots become inflamed or don't heal adequately. While scarring for some people seems to depend on inherited factors or skin color, precautions can be taken to prevent scars and treatments are available to significantly reduce scarred skin's appearance.

In the simple words, scars are the visible reminders of injury and tissue repair. In the case of acne, the injury is caused by the body's inflammatory reaction to sebum, microbes and dead cells in the clogged sebaceous follicle. Two types of true scars exist:

(1) Depressed areas like in pitted acne scarring, and

(2) Raised thickened tissue like in keloids.

When a lesion happens the body sends in the 'troops' to heal the damage. However, when their job is done they may leave behind a mess in the shape of fibrous scar tissue, or eroded tissue. Leukocytes and inflammatory molecules may remain at the site of an active acne lesion for days or even weeks. For those who are prone to scarring the outcome can be an acne scar.