I live in a state where marijuana is legal and recently tried it again for the first time in over a decade. I strolled into a recreational store and asked for a recommendation, specifically requesting a flower with a low THC concentration. They ended up giving me something ("Biker Kush") that had 28% THC, which I had only noticed on the packaging after I left the store. Gee, thanks. Anyway, then I bought supplies to make one marijuana cigarette, sometimes also called a "joint." I did not want to get too high, so I smoked one hit at a time, putting the joint out for breaks of twenty to thirty minutes between attempts. After around four of those hits spread over two hours, I did not really feel anything.
The next day, I bought a one-hit dry herb vaporizer, to be heated with a butane torch. I wanted to feel "high," and the joint had not worked. I used the same approach of waiting twenty to thirty minutes between hits with the vaporizer. In most of these hit attempts, the marijuana ended up combusting instead of vaporizing, as I had heated it up too much. For the first three hits, I did not really feel anything. However, the fourth hit was very rough, burning my throat, and sent me into a coughing fit.
Over a period of about fifteen minutes, the effect began to take hold. I decided to take a shower, and I started freaking out about halfway through, calling out to my wife. I thought I was having a stroke and suddenly felt like I did not have control over my body. I went up to bed and lied down for a long time, where my mind was racing with obsessive, intrusive thoughts. It felt like I was not the person controlling my actions or my thoughts. The feeling that I would be stuck like this forever - that I had lost my mind and entered some state of irreversible psychosis - persisted for at least an hour while I desperately tried to relax myself. After some amount of time, I got out of bed and threw up in the sink and the toilet, then went back to lie down. The entire night, I felt unable to express what I was thinking, but it was filled with the greatest worry that I have ever experienced. (I say this as someone who had actually experienced a couple panic attacks over a decade ago.)
The next day, when I woke up, the effects had subsided, but I was still left with a feeling that I was milliseconds behind the present moment. The worry that I would never feel normal again continued even after the high had diminished. It's a very difficult feeling to explain in hindsight, but after a bit of research, I think I experienced what's called "derealization." This continued into the rest of the day and a bit into the next, and it was a really scary situation for me, since I feel like I always need some amount of control over my mind. (Alcohol has never made me feel this way, though.)
Anyway, the derealization effects were gone after two days, and now, I'm afraid to try marijuana again. I would really like to enjoy the pleasant feelings reported with its use, but I'm worried that my personality is such that I just can't lose control over whatever part of my brain is affected by THC. But I also partly blame the salesperson who sold me something with such a high THC concentration, when I specifically requested something with a low concentration.