Supplements containing testosterone as a hidden ingredient may potentially reduce or shut down endogenous testosterone production.

“Now, with all of that said, there are some supplements out there that include testosterone as a ingredient that's been snuck in to various formulas that include blends and things of that sort. You want to be aware of that. ... Whether or not they can shut down your own endogenous testosterone production isn't clear. No one's really explored that in detail. But based on everything we just talked about with TRT, it stands to reason that it might either reduce it or shut it down.”