Is Propecia good in solving hair loss problems?

I began losing my hair a few months ago. At first I wasn’t worried, but it is just getting worse day by day. Is this normal? I was looking into using propecia to solve my problem as I have heard excellent reviews of it. But my doctor told me that he won’t prescribe it for women. Why is that? I want to know what it contains that I can’t use it? I don’t have any kind of allergy also.Please help.