To ensure that each patient receives the most effective treatment for his or her individual problems, doctors employ a special scale known as the acne grading scale. The acne grading scale rates the severity of acne on a scale from zero to eight, with zero indicating very mild acne and eight indicating very severe acne. For example, if a patient has a few comedones, he or she is given a zero rating. The rating increases with the number, size, and severity of a person’s lesions. Therefore, a patient with half of his or her face covered with papules, comedones, and a few pustules receives a four rating, which denotes moderate acne. A rating of eight indicates very severe acne, with the patient having acne lesions of all types, including numerous cysts, covering almost all of his or her face. Once a person’s acne has been rated, doctors match the rating to specific treatment plans recommended by the American Academy of Dermatology, an organization that studies skin diseases. At the same time, the doctor makes adjustments in the recommended treatment for individual differences. For example, these differences may include such factors as how dry or oily the patient’s skin may be, the patient’s gender, whether the patient is allergic to any medications, and whether the patient is pregnant or planning to become pregnant soon.