For civil aviation? I’ve yet to see one.
The usual suspects are safe for the average, healthy individual. Protein powders, BCAAs, creatine, etc. When you start getting into things like fat burners, pre-workout, testosterone boosters, etc—use caution. Make sure all of your supplements have been tested by a reputable, independent lab (USP, etc). I personally know of someone who popped positive for amphetamines after using a pre-workout he bought off the internet. Whatever was in it was close enough to an amphetamine to cause a positive result. Woof.
I don’t buy my stuff from a brick and mortar store like a GNC, but if GNC doesn’t sell it (IOW, internet only) I would be wary.
He did say it was the best PWO he ever used, though! Personally, I stick to Monster or black coffee for PWO.
The Navy classifies workout supplements, and I typically abide by their chart and recommendations. Well, with the exception of caffeine—for me, breakfast consists of caffeine and hatred.