Controlled medicinal use of sodium oxybate under the supervision of a medical professional differs greatly from microdosing/self-medicating cleaning agents turned into GHB by yourself or your local dealer
But "microdosing" per se isn't the issue.
I once stumbled upon a psychiatry case report about a man with a psychotic illness, who found out by experimentation that taking significantly less of his antipsychotics than prescribed, along with up-titration when he began to notice the prodromal signs of relapse, helped him avoid relapse while also avoiding most of the unpleasant side effects. He did this on his own, only later confided in his psychiatrist he was doing it. Some psychiatrists would have reacted rather negatively, but his (being somewhat influenced by R. D. Laing & friends) actually thought it was smart, and wrote it up.