Acne is a chronic self-limited disease, which affects mostly teenagers, without gender difference. In recent years, the incidence has increased in female adults. The factors involved in this epidemiological observation are still under discussion in the literature. Clinically, acne is characterized by different types of lesions. The disease affects the regions rich in sebaceous glands (face, chest and upper back). The clinical lesions are: open and closed comedones, erythematous papules, pustules, nodules and different types of scars. Taking into consideration the general concept of inflammation (redness, pain, heat and loss of function), acne is traditionally classified as non-inflammatory (open and closed comedones) and inflammatory (other primary lesions). With the knowledge advancement this concept seems to be wrong and therefore acne would be an inflammatory disease even before the onset of their clinical lesions.