Somewhere between 48-72 hours (don't remember, had a psychotic break). I asked to be hospitalized at the 24 hour mark. After that, the doctors tried a medley of sedatives, antihistamines, etc. but nothing would knock me out (and/or I'd vomit it up). It was a bizarre time, and I had mono too, which must have worsened the situation. My BP wasn't diagnosed until a year later, however.