Waxing and waning gynecomastia: an indication of noncompliant use of prescribed medication.

We present two cases of recurrent gynecomastia in men enrolled in a placebo-controlled trial evaluating the efficacy of finasteride in treating benign prostatic hyperplasia. When the pharmacologic records were examined, it was apparent that the breast tissue hyperplasia diminished when the patients become noncompliant with their study medication and then resumed therapy. Because of the difficulty in obtaining accurate data on an individual's ability to maintain a consistent pharmacologic regimen, we believe that observing such "waxing and waning gynecomastia" may provide the physician with a clue regarding a patient's actual compliance with certain medications.