Can you tell me, When using Propecia (3 months) is it safe to have unpretected sex without dangering female partner?
There is no danger to your partner from finasteride (Propecia) by having unprotected sex while you are taking this drug. Propecia’s manufacturer, Merck, does not warn of problems in this regard.
The question I am often asked is whether unprotected sex and pregnancy could cause problems for a man on Propecia. I believe that the answer to this question is that getting your lady pregnant should not be a problem when on Propecia, but if you are concerned about it, then you might stop taking it during the period when she is most fertile. I’ve written about that previously here and here.