When I was 16, I brought some anhydrous caffeine tablets to a party where I was planning on staying awake for a couple days after only sleeping half an hour the night before. This one chick (who would unsurprisingly get addicted to meth about 4-5 months later) asked for one, and then started crushing it up and doing lines of it. And that is how I got half of the grade below me addicted to doing lines of caffeine.
It never really did much for me (luckily), but it is pretty cardiotoxic. A friend of mine (who has some serious issues) crushed up about ~10 200mg caffeine bars the day after we did DXM and started doing lines with this girl we were hanging out with. They couldn't have done more than 800mg between the two of them based on how much was leftover, but he found out a few months later when he ended up in inpatient that he had an irregular heartbeat, which he attributes to the intranasal caffeine.
tl;dr: Don't snort caffeine. If you have to use caffeine powder then take it orally and try to limit yourself to 200mg every 4-6 hours.
