Acne is typically caused by the clogging of hair follicles by debris from skin cells, skin inflammation, oily secretions and certain bacteria.
The American Skin Association identifies these common types of acne and their causes:
- Comedones- These are non-inflammatory acne lesions and may be open or closed. Closed comedones are commonly called whiteheads. Open comedones, also known as blackheads, allow oxidation of debris within the follicle, leading to the black color.
- Inflammatory – When lesions become red and tender, they are called papules. These bumps often fill with pus.
- Nodular- As lesions progress to become larger and more tender, they are referred to as nodules.
- Nodulocystic- Characterized by deep, fluid-filled cysts. When these occur along with nodules, the term nodulocystic acne is used.