Non-inflammatory acne often takes the form of a closed comedo, or whitehead. This occurs when the plugged hair follicle stays beneath the surface of the skin, and appears on the skin as a small whiteish bump.
An open comedo, or blackhead, occurs when the plug enlarges and pushes through the surface of the skin. Its dark appearance is not due to dirt, but rather to a build up of the dark pigment of the skin called melanin. Blackheads are also a type of inflammatory acne.
The mildest form of inflammatory acne is a papule, a small, firm, pink bump appearing on the surface of the skin. These bumps can be tender to the touch, and are often considered an intermediary step between non-inflammatory and inflammatory acne.
Pustules are like papules in that they are small, round lesions. Unlike papules, pustules are clearly inflamed and visibly contain pus. They may appear red at the base with a yellowish or whiteish center. Pustules do not generally contain a great deal of bacteria, but are inflamed due to chemical irritation from sebum components.
Nodular or cystic acne is usually very painful. Nodules are inflamed pus-filled lesions lodged deep within the skin. They develop when the contents of a comedo has spilled into the surrounding skin and immune system responds, producing pus. The most severe form of this type of acne may persist for weeks or even months, eventually hardening into a cyst. Both nodules and cysts often leave deep scars.
Acne conglobata, a rare form of inflammatory acne, forms primarily on the back, buttocks, and chest. It is characterized by pustules and nodules, and severe bacterial infection may ensue.
Acne cosmetica is a relatively mild form of acne caused from topical cosmetic products. It is characterized by small pink bumps, and local inflammation on the cheek, chin, and forehead. It may develop over the course of a few weeks or months, but usually does not cause scarring. Since it can persist indefinitely, it is important to find out which topical products are causing the problem and eliminate their use.
It is important to understand what is causing your acne so a suitable treatment can be found. Before you can solve the problem, you must know its origin.