This question is pedantic but I’ll ask it anyways: is it actually illegal to take an unapproved drug? Sale of, marketing for, distribution, etc. all might be (are?) illegal but is TAKING an unapproved drug illegal? I can’t believe it is, there’s an entire industry that peddles nootropics and supplements. My understanding has always been that if you can get it (however that is), you can take it without issue (although you obviously might have broken a possession law at some point).
Depending on the drug, it can be illegal for certain professionals to create, procure or otherwise transfer possession or sell it to you. It's not even illegal to consume heroin or crack in normal circumstances, it's only the possession itself which is illegal.
Depends on the state, but unscheduled drugs don't typically have possession laws. However, if you use an illegal method to acquire them, and in some case all realistic methods are illegal, you can get in trouble for that.
Isn't the FDAs rule it becomes controlled once the active ingredient in the supplement is proven to have significant pharmacological effects on health conditions? So you can take it up to and until it becomes clear it has a benefit to you, the you can only take the FDA approved version.