Habitual picking or squeezing of moderate acne results in formation of severe acne. The main difference between moderate acne and severe acne is that the amount of inflammation present. Since the amount of inflammation present in severe acne is large, the skin is obviously reddened and inflamed. In this case of severe acne, papules and pustules have developed in greater numbers. The areas which get infected due to severe acne are the neck, chest, shoulders and upper back, as well as the face. As the infection spreads and becomes deeper the chance of scarring becomes higher in case of severe acne. Severe acne should not be treated at home. It should be treated by a dermatologist. Severe acne is usually treated with both topical and systemic therapies available only by prescription. Left untreated severe acne results in cystic acne which is most infected when compared to severe acne. Thus cystic acne is the most severe form of acne.