I wasn't really sure where to post this, but here we go....
So yesterday, I ran out of preworkout and decided to pick some up from my local supplement shop (Vitamin). Usually, I'm not too picky on what type I get since most of them are pretty much the same (getting you a little hyped up for lifting). Since there was kind of a sale going on, I picked up a product called Mr. Hyde. Most preworkouts can range from 35-45 USD depending on how fresh it is or how popular it is. In this case, I wanted to pick something as cheap as possible because I don't find preworkouts to be necessary to any lifting.
At this point into my lifting career, my body has developed somewhat of a tolerance to some preworkouts. So like any other preworkout I took in the past, I dumped a scoop and a half in there, and started drinking it to the blasting music in my car.
By the time I got to the gym, I started to notice that the caffeine felt really intense and my heart was beating at an insanely high rate. Everything was shaking and I felt like I was about to black out at any given second. I'm not sure why I just didn't dial 911, but I rushed back to my car and looked at the nutritional facts on the product itself.
It wasn't after until I found out that I actually had somewhere close to 700 mg of caffeine in one drink less than 15 minutes. I felt like I was about to die and my anxiety was actually through the roof. Luckily, I was smart enough to call 911 just in time and have the paramedics monitor/take care of me. My heart rate was pretty high, but was actually still beating very normal from what the doctors told me.
Moral of the story is, if you're going to take a preworkout, read the nutritional label on the back of the product to make sure you're not going to crazy with the caffeine. I'm actually legitimately scared of taking these products and it's definitely not a necessity to become successful.