I don't know the medical answer, I only know from my experience.
About a year ago I was drinking a LOT of caffeine in the form of energy shots (not the sugary stuff). Those things are pretty awesome and get me going when I don't feel motivated, but I was drinking so much that I would get angry at very little things... my body and mind were rejecting the levels of stimulants I was taking in and my blood pressure was constantly on the verge of rising.
The two worst experiences I had with DMT were during those times. Once, I could feel my blood pressure rising like I was getting really pissed off at something, except that it was during the buildup phase after I had smoked maybe 20 mg. I saw the color red as it built and I knew I was in for an uncomfortable experience. It was intolerably intense, my head felt like it was going to explode, my "vision" was filled with colorful Aztec type imagery, complete with a very angry god-like being in the center that seemed to hate me to the core. The visuals felt like they were being shoved against me so they would hurt, and they throbbed and shifted, and morphed. But it was painful.
The second related experience involved me feeling like I had been shot in the head. I posted a report about that. In short, it was interesting, fairly painful, very uncomfortable, incredibly confusing, and not something I want to experience again.
Like I said, I don't know about the medical side of things, but experientially, if I feel myself experiencing similar symptoms like I was then (irritability, etc) that tend towards increasing my blood pressure, I won't do anything. I am afraid my brain will explode
