Bilateral treatment for alopecia areata.

A 4-year-old, otherwise healthy white girl was referred for a 15-month history of alopecia areata. Anthralin 0.1% cream was prescribed for the left side of the scalp, while corticosteroids for the right side. After 4 months, only the right side of the scalp showed hair regrowth. Half-side strategy, that is, treating one side and managing the other--divided by the mid sagittal suture--as an internal control for no treatment, placebo or other treatment, has been commonly used in clinical studies for decades. In everyday practice, bilateral treatment is useful to evaluate the responsiveness to two topically delivered interventions and diminishes the time necessary to identify an effective one.