I've had debilitating anxiety and social phobias since puberty, and have been on a slew of medications to combat it since. I'm currently barely functional at the age of 32.
A few years ago I tried a new medication. The first time I took it, I began to feel sick. I want certain it was the pill I took, as I frequently get sick to my stomach anyway. The next night, I was feeling a bit better but decided since there was a strong possibility it wasn't the pill, I took another dose. Again got sick, worse than the day before.
Stupidly, the next night I decided to power through it, figuring I could just let my system acclimate to the new med and I'd end up being fine. Took my third dose, and that's when all hell broke loose.
I got horribly sick. I mean the first couple days sucked but then it was basically just nausea. This was a whole nother world of sick. It started with projectile vomiting. That lasted a few hours, maybe four. By then I was also sweating heavily, felt like I had a very high fever. I was exhausted from all the vomiting, so I tried to get some sleep. Kept a trash can next to me, just in case. Still feverish, sweating and shaking, I managed to get some sleep. Was plagued by vivid, terrifying nightmares.
It got worse. I had a hard time sleeping. Started hallucinating, talking in my sleep. At one point I decided to move to the couch so I wouldn't bother my wife anymore. Everything continued out there, getting gradually worse, until I realized I was having a heart attack. Woke up my wife and had her take me to the emergency room. I had a panic attack in the waiting room. Biggest panic attack of my life.
They performed tests and made sure I was ok. We went home and I slept more, and each time I awoke I felt slightly better. I eventually got back to normal, but it took a few days.
When I was lying on the couch, having my first heart attack, was the scariest moment of my life. Really didn't think I'd make it through that.
I still don't remember much of those three days. I wasn't conscious enough to really be aware of what was happening.