involves areas of the skin that are transforming from the small vellus type to the larger terminal type. This change normally occurs during adolescence, when vellus hair follicles in the underarms and groin grow into terminal hair follicles. Hypertrichosis involves this same type of switching, but in areas that do not normally produce terminal hair. The mechanisms for this switch are poorly understood. Another mechanism involves a change in the hair cycle. There are three stages of the hair cycle: the anagen phase (hair growth), the catagen phase (hair follicle death), and the telogen phase (hair shedding). If the anagen phase increases beyond what is normal, that region of the body will experience excessive hair growth. Diagnosis Hypertrichosis is diagnosed clinically by the occurrence of hair in excess of what is expected for age, sex, and ethnicity in areas that are not androgen-sensitive. The excess can be in the form of excessive length or density and may consist of any hair type (lanugo, vellus, or terminal). Management There is no cure for any congenital forms of hypertrichosis. The treatment for acquired hypertrichosis is based on attempting to address the underlying cause. Acquired forms of hypertrichosis have a variety of sources, and are usually treated by removing the factor causing hypertrichosis, e.g. a medication with undesired side-effects. All hypertrichosis, congenital or acquired, can be reduced through hair removal. Hair removal treatments are categorized into two principal subdivisions: temporary removal and permanent removal. Treatment may have adverse effects by causing scarring, dermatitis, or hypersensitivity. Temporary hair removal may last from several hours to several weeks, depending on the method used. These procedures are purely cosmetic. Depilation methods, such as trimming, shaving, and depilatories, remove hair to the level of the skin and produce results that last several hours to several days. Epilation methods, such as plucking, electrology, waxing, sugaring, threading remove the entire hair from the root, the results lasting several days to several weeks. Permanent hair removal uses chemicals, energy of various types, or a combination to target the cells that cause hair growth. Laser hair removal is an effective method of hair removal on hairs that have color. Laser cannot treat white hair. The laser targets the melanin color in the lower third of the hair follicle, which is the target zone. Electrolysis (electrology) uses electrical current, and/or localized heating. The U.S. Food and Drug Administration (FDA) allows only electrology