It depends what you area taking it for. For hypertension it can go all the way up to 640mg. That would be pretty dangerous of course if you didn't have really high blood pressure.

I take it for Latuda-induced akathisia. We started at about 20mg and then went up until it worked completely at 80mg. Doctors always compliment me for having such great blood pressure and I feel like I'm cheating. But that dose hasn't lowered my bp too much. If my heart is pounding and I feel shaky and as though I can't catch my breath I take an extra one and it works. My psychiatrist was pretty much "whatever".