Topical Minoxidilfor Hair Loss in Women REQUEST What is the effectiveness of topical minoxidil in treating hair loss in women? RESPONSE Minoxidil, a potent peripheral vasodilator, was first introduced as an oral agent used to treat resistant hypertension. Because one of its side effects was hypertrichosis, minoxidil quickly received attention as a potential treatment for hair loss. In 1980, the reversal of male-pattern baldness in a patient receiving oral minoxidil for hypertension was reported by Zappacosta. 1 Since this report, many studies have been conducted to determine if topical minoxidil is effective in restoring hair. However, most of these investigations have involved men rather than women. The two major types of hair loss are androgenetic alopecia and alopecia areata. Only one study investigated the effectiveness of topical minoxidil in treating women with androgenetic alopecia and several studies have investigated the effectiveness of topical minoxidil in the treatment of both women and men with alopecia areata. Alopecia areata occurs in a wide age range of individuals. Usually it is first seen between 5 and 40 years of age. Complete hair loss occurs in large patches on the scalp or on other areas of the body including eyelashes, eyebrows, beards, and pubic hair. The duration of hair loss is variable and the patient may experience continual cycles of hair loss and regrowth. Alopecia areata is divided into several categories according to the severity of hair loss. Alopecia total is is the loss of all scalp hair. Alopecia universalis is the loss of both scalp and body hair. The pathophysiology is still not understood, but endocrine and immunologic factors are being considered. 1 Androgenetic alopecia is the less extensive of the two disorders. This form of hair loss is commonly seen in middle-aged men where frontotemporal recession occurs to form the typical male-pattern baldness. The Hamilton classification scale is often used to rate the degree of hair loss. It consists of eight groupings where type I denotes a full head of hair and type VIII denotes complete loss of hair on the top of the scalp. Men who are 50 years old or older usually have types V-VII hair loss, whereas women usually do not have hair loss any more severe than type IV. 3 Genetic predisposition and androgen production are necessary factors in both men and women. In women, the age of onset occurs between 26 and 30 years and may be accompanied by acne and hirsutism.• · In 1988, Hordinsky and Shank conducted a study using 3% topical minoxidil to treat androgenetic alopecia in 25 women. The women applied 1 mL of 3% minoxidil to their balding areas every 12 hours for 48 weeks. Photographs and baseline measurements (including hair counts and the average distance between hairs) were taken. In addition, improvement in hair growth was determined by the patient's observations of changes in the amount of hair loss and also the investigators' visual comparison with previous photographs. These observations and hair measurements occurred every four weeks for the first six months and then every eight weeks. The investigators concluded that minoxidil was effective in treating hair loss in a majority of the women. By comparing the patients' hair before and after treatment, statistically significant improvement was seen (p