i have smoked this many times and not had any problems but one day friend came over and we rolled a joint of it i felt fine usualy how i do after feels like smoking bud but little more intense. then i remembered i had a blunt in my room so rolled that up. 10 minutes later had worst anxiety attack of my life i started freaking out every time my friends mentioned word k2 i would go nuts and freak out so eventually he left me alone then i spent 3 hours curled up in bed hyperventeling. i know story sounds ridicoulus but the messege is just dont over due i smoked more in the morning and it was fine and have been doing ever since. its great if wanna get stoned and have to pass urines. its more potent then alot of bud and small amounts go a long way