There’s something called consensus reality which basically means you’ve gotta ask someone else if it’s true. However, once you take medicine you can sorta tell what’s real or not just by probability or the way they quickly cut out or whatever. Like I had these Asian ladies in kimonos walking around and I turned my head for a split second and they were gone. This was while I was In the psych ward so it was unlikely and the quick vanishing act made it virtually impossible. But at the time it was 100% real. Part of this is that most hallucinations are combined with delusions.