Re: Is this dangerous?
I once went for a checkup and the nurse measured me, measured again, got a different cuff and measured me, left the room, came back 5 minutes later, measured me, left, the doctor came in and measured me, and then he asked...."are you feeling all right?"...."Yep, just a little stressed from the day, why?"...."Well, your blood pressure is high"...."oh yeah, how high?"..."well, after resting in the room for a while, 190/140". HOLY COW.
I didn't fight the meds and neither should your friend...that is so high that even if he doesn't have a stroke or heart attack, he could be doing damage to kidneys, etc. Have him measure it several times over a few days to convince him it wasn't a random spike but even with spikes like that, I would be on something.
Tell your friend that he/she needs to heed the doctor's advice.