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Ms. Terrie is a clinical pharmacy writer based in Haymarket, Virginia.
Androgenetic alopecia (commonly known as pattern hereditary hair loss) is the most common type of hair loss, affecting an estimated one third of all men and one sixth of women in the United States.1 Dihydrotestosterone plays a key role in this androgen-dependent hereditary disorder.2 The condition can start at any age, but an estimated two thirds of men will experience some degree of hair loss by age 35; it is estimated that 85% of men will experience significant thinning of the hair by age 50.3 As many as 13% of premenopausal women report some degree of androgenetic alopecia, and the incidence may increase significantly in women after menopause.4
Hair loss also can be nonhereditary. Causes of nonhereditary hair loss include acute or chronic illness, use of certain medications, trauma, dietary changes, endocrine disorders, and hormonal changes during or following a pregnancy.1 Currently, androgenetic alopecia is the only type of hair loss that is effectively treated by OTC hair loss products.1
Among men experiencing androgenetic alopecia, hair loss often begins at the temples and crowns. Some men experience partial or complete baldness.1 Common symptoms for women are thinning of the hair at the front of the hair line, as well as the sides or crown.1
Hydroalcoholic topical solutions of minoxidil 2% and extra strength 5% are the only FDA-approved OTC products available for the treatment of androgenetic alopecia.1 Minoxidil is indicated for the treatment of baldness at the crown of the head in men and for thinning of hair at the frontoparietal region in women.1 Whereas the exact mechanism of action is unknown, minoxidil appears to increase cutaneous blood flow directly to the hair follicles, which then increase in size after treatment. In addition, minoxidil promotes and maintains vascularization of hair follicles in alopecia.1,4,5 Some individuals with other types of hair loss, such as alopecia areata, have reported some success with the use of these products.1 Patients with sudden hair loss or nonpattern hair loss always should be encouraged to seek medical advice before using minoxidil. Table 1 provides examples of those symptoms for which self-treatment is not advised.
Topical minoxidil 2% can be used in both men and women, but the use of 5% topical minoxidil is indicated for men only.1 The use of 5% minoxidil by women is contraindicated due to an increased risk of facial hair growth.1 No known drug interactions are associated with the use of topical minoxidil. It is important to note that the concurrent use of minoxidil with guanethidine may enhance the incidence of orthostatic hypotension, and concurrent use of oral minoxidil may increase systemic concentrations and potentiate its effects.1,4
Because minoxidil is absorbed through the skin in low concentrations, the incidence of systemic adverse effects are rare. The most common adverse effects associated with the long-term use of topical minoxidil are transient hypertrichosis and local itching or irritation.1,2 Minoxidil should only be used by individuals 18 years and older. Table 2 lists examples of OTC topical minoxidil products.
Pharmacists can assist patients experiencing hair loss by reviewing medication profiles and identifying those pharmacologic agents that may be associated with increased risk of hair loss. Prior to recommending the use of topical minoxidil products, it is important to determine if self-treatment is appropriate and if the cause of the hair loss has been identified. Patients always should be referred to their primary care physician for further evaluation if the cause of hair loss is unknown or sudden. It is important for women who experience hair loss to be evaluated by their primary care physician to ascertain possible causes or contributing factors.1
Patients must be counseled on the correct use of minoxidil, as well as the importance of adhering to continuous use of the product to maintain regrowth of hair.1,3 Continuing topical treatment is necessary indefinitely, because discontinuation of treatment produces a rapid reversion to the pretreatment balding pattern.1,4 Patients should be advised not to apply the product more than twice a day and not to apply to damaged or inflamed areas of the skin.1 The product also should not be applied 24 hours before or after the use of hair color, relaxer, or permanent.1 In addition, pharmacists should inform patients that the product may not be effective for everyone and that it is a suppressive therapy and not a cure.1,3 Patients also should be informed that if no sign of new hair growth is apparent 4 to 6 months after initiation of therapy, then use of the product should be discontinued, and consultation with the primary health care provider is recommended.1