With 24 million results associated with Google's searchon keywords severe acne, Pr Dreno's team understand better thatthis disease, which affects many French people, is a real concern of Public Health and not a forced evil of the adolescent period, which will eventually resolve itself. Acne does not affect the vital prognosis, but its psychosocial impact is major and should not be underestimated. Paradoxically, despite the high prevalence of acne, few quality epidemiological studies have been published. Physicians are often helpless when faced with patients' questions. They often need a lot of explanations, especially on the factors aggravating this dermatosis, which greatly affects their quality of life. This cohort, the first of its kind in France, will determine the predictive factors of therapeutic response, endogenous and environmental factors impacting on the severity of acne assess the quality of life and psychological impact of acne patients, determine the patient's course of care and the associated costs. Pr Dreno's team will also build up a bio collection (bacteriological samples).