What is acne vulgaris?

What is acne? When we say “acne,” we typically mean “acne vulgaris” and that is the sense in which I will use the word “acne” on this page. There is also another disease called “acne rosacea.” What happens in acne? 1. Excessive amounts of dead skin cells (keratinocytes) block the hair follicle (“pilosebaceous duct”). 2….