I have been diagnosed with adhd when i was 8, again when i was 16, and again now, when i'm 21. I've been using methylphenidate for about a year now, have never had a problem with abuse before three/four months ago. I had a problem where i would constantly feel dizzy and i couldn't concantrate because of it. I had snorted ritalin before this but i didn't really enjoy it, and didn't do it regularly until i started feeling dizzy and unconcantrated. I started tapering two weeks ago, and got down to 20mg snorted, until i got a refill where i relapsed. I snorted 30mg today, and i have felt fine. I also started taking nac, should i stop? Should i taper off or go cold turkey? Should i start using methylphenidate again after a while?