Risk level of Rogaine with cats

[Brendan]

I'm hoping to begin treating my thinning hair with Rogaine, but I've read the active ingredient, Minoxidil, is quite toxic for cats. The thing I can't discern is if this is just if they accidentally consume it, or if its even dangerous to share an environment. As a precaution my plan would be to ensure he doesn't have access to my bedroom or the bathroom, but would this be enough to ensure I'm not putting him at risk?