I can tell you that high doses of DXM tend to cause a rise in blood pressure for me - not too extreme - it has exceeded 170/105 while I felt really anxious but generally it is more like 150-165/90-100 and my pulse does not change much.
Do you take any prescription meds that may interact? Anything with stimulant effects would be bad news. Wellbutrin might even be dangerous with DXM. And if you take an SSRI or SNRI that might cause serotonin syndrome. Serotonin syndrome could cause severe hypertension and tachycardia. There are other meds that could cause serotonin syndrome when mixed with DXM. If you take any prescriptions that may be bad to mix with DXM, post the names and someone could tell you if that could be the culprit. I know mixing with anything that raises serotonin levels can be dangerous and you can die from mixing with stimulants.
The next paragraph is just about what happened when I mixed DXM with ephedra long ago and the one after that explains how that overdose that could have killed me probably saved me from death or disability by getting me to see a doctor for the first time in many years to diagnose my severe hypertension - fucking weird how that turned out.
I did have a severe hypertensive crisis when I was like 22 or 23 years old because I took first just a couple of ephedra pills (ephedrine is a stimulant) and then it seemed as though I was just watching my body do things by itself later as I proceeded to consume probably at least another 20 ephedra pills. This was with pure DXM and it took a lot longer than usual to kick in so I redosed on that and initially took the ephedra to stay awake for the trip. I was not in control when eating the rest of those pills. My blood pressure was 300/200 according to my mom (I would not know as I was having an out of body experience most of the time until right before I went to the ICU but the doctors tried to scare me later by telling me it was even higher - but they were bullshitting me because blood pressure can't get that high and there are no devices to measure it if it did. There have been a few other cases of blood pressures of 300/200 reported by nurses online so that might have been real but the official world record is 300/190 - I want to get my old records if they exist and see if it was really that high, maybe I made a new world record. She probably rounded upward or something though. It would be kind of cool to get in the book of world records if it really did get that high.) and it caused some bleeding on my retinas - did not cause any vision loss though. I remember them asking if I wanted a priest to give me last rites after they got it down enough to move me to the ICU (I was having a really interesting trip before flying through the hall while they pushed me that way, it seemed like I was flying on a UFO or something). I was thinking "Why the fuck are you asking that, I am not sick or anything.". I had no fucking idea how bad I fucked up until later. They would not believe I took DXM and ephedra, they said it would not cause a positive for opiates or amphetamines and they insisted I od'd on ecstasy and heroin. The fucking doctor came in and started talking in a mean voice and telling me I was wasting space that other patients might need while my blood pressure was still going between the 230s and 240s over something and I think it was lower before he came in and started making me feel anxious and like a scumbag. He could have waited until I was more stable to tell me I was a waste of space. And they are doctors, they should know at least that ephedra causes positives for amphetamines - not sure if it would even be a false positive given the structure.
It turned out I had severe hypertension to begin with as it was still really high 3 days later when I was released and when I got in to see the doctor the next week with nothing to make it high it was over 190/120. I had not seen a doctor in 7 or 8 years. He told me I would be dead within two years without treatment for the hypertension and if I had not had that overdose I would have never went to see a doctor. It strangely may have saved my life. That also means my body was accustomed to very high blood pressure so I would be able to survive something like 300/200 far easier than probably 99.5% or more of people, it is rare for someone to have hypertension as bad as mine was undiagnosed.
I am high on meth, excuse the rant but it is weird to think if I had not had that overdose that could have killed me I would have probably either been diagnosed with hypertension after it caused a stroke or heart attack or I would have just straight up and died. Sometimes things work out in really bizarre ways.
