I think part of maintaining that ability to have an erection is trying.
Most of the people Ive seen commenting that cant tend to be severely bottom dysphoric. Not all of us are, nothing wrong with that especially if our partners/sexuallity allows it.
Ive def seen a decrease in it. It goes away when I want it too and and comes back when I want it to, lol.
Viagra could be a bad idea without doctor consult as typical t-blockers lower blood pressure, and so does viagra. It wouldnt be as bad as nitroglycerin and viagra, but still a problematic or fatal combination if you have the right conditions.