No idea what paracetem does...
Amphetamines are great until you get a heartattack or go batshit crazy. Not worth the risk. Ok for weightloss but way too dangerous in my opinion. Quit it and you'll be down for what seems forever. I put phentermine in the same class
Beta blockers, now that's a first... Always thought they're boring blood pressure drugs or something...
Ritalin is OK, but you can get habituated, not entirely sure there aren't any negative side effects (certainly not as creative on Ritalin).
IMHO Best cognitive enhancer with few side effects: Exercise! Read "Spark", tried the 80% of max heartrate for 30 mins a day and boom! It works! Good ol BDNF. Better concentration, creativity & less depression. Also helps create new brain cells... I hate exercising, but now I pop in a audible & take the much needed 45min refresher every day. Haven't tried with any combination of enhancers, though beta blockers are probably not a good fit right off the bat & I wonder if Amphetamines wouldn't make you heart just want to explode...