Does taking propecia (finasteride) lead to a lowered testosterone level?

It doesn't . . .: Finasteride (and dutasteride) will not lower your testosterone level. In fact, studies show that it might increase it. However, these two 5 Alpha reductase inhibitors used for enlarged prostate and in male pattern baldness could also lead to higher Estradiol level which could then cause gynecomastia (nipple sensitivity +/- male breast development), erectile dysfunction, and a reduction in libido.

No: Propecia (finasteride) will not lower testosterone levels. It will, however, lower DHT levels and can raise estradiol levels. Elevated estradiol levels can lead to gynecomastia and/or breast tenderness, and/or decreased libido.