Do not take 5 alpha Reductase Inhibitors meds such as Propecia aka know as finesteride or dustasteride, you may have permanent ED!!!
Did you use it against hair loss? I read that permanent ED is a known rare side effect by now and the pharma company that produces it, is facing thousands of lawsuits at the moment. I suffer from hair loss too and I read about this being the only drug that helps it. But the side effects are too much of a risk. It's not safe. I'd rather save 10.000 $ and pay for a hair transplantion by a surgeon than gambling with this dangerous drug.
Well, since you likely stopped taking it, you're most likely facing even more hairfall now. Medication is not the way to treat hairfall with any reliability. Not in 2020; maybe by 2030, with current research. Your best option is a hair transplant, which is much less risky, significantly more likely to work and does not build dependency. Your next best option is to get a wig. Or, if you can, as the gentleman above me very aptly suggested- go bald.