150 mgs is not a lethal dose barring pre existing heart issues. I regularly dose that much and above at one time when I use adderall, sometimes use 300+ mgs a day, but the first time i did 90 mgs over 6 hours I was convinced I was dying because of the side effects and not knowing what to expect threw me into complete panic which made it so much worse. It can just feel extremely unpleasant if you're not used to it especially on the come down. Force yourself to lay down and Remind yourself to breathe and stop googling adderall overdose symptoms and the like cuz it will just make the panic worse and you'll convince yourself you're dying. Put on music or a movie, something to take your mind off of it. DO NOT drink caffeine it makes the jittery panic feeling so much worse. If you have access to clonidine or gapabentin or a muscle relaxer take those to smooth the side effects out. Opiates and benzos are great too but if you don't have a tolerance those can get tricky, so start with something safer if you can. I love gabapentin for this it works wonders and is easy enough to get a hold of And pretty safe.