And for the quote from wikipedia:
"Aside from causing intense pain, the venom of the spider can also cause priapism - uncomfortable erections that can last for many hours and lead to impotence. The venom may eventually be used in erectile dysfunction treatments."
Incase you want to read the full article:
http://en.wikipedia.org/wiki/Phoneutria_nigriventer.
Weather you still have those problems after the antivenom has been administered I don't know. But it sure would suck lying in a hospital with a painful erection for a few hours.