Rogaine the hair grower product for men was originally supposed to be for high blood pressure but they found that when men take it they grow hair so they rebranded it.
Fun fact: They do, in fact, still prescribe it for some blood pressure patients. They just call it Revatio and it's a bit smaller of a dose. (5/10/20mg instead of 50/100mg) However, you don't see it prescribed very often because most insurances won't pay for it.
The same way, Poppers were originally made to cure anginas.