How often does the drug spironolactone cause breast enlargement in women?

The use of: Spironolactone is not associated with breast enlargement (that I have ever seen or heard) good luck.

Not in women: Spironolactone (aldactone) is an antiandrogen, so it does have an effect to decrease testoterone, and there is an indirect estrogenic effect - which can cause breast enlargement (gynecomastia) and tenderness in men. Breast tenderness is occasionally reported in women, but this is unusual.