make sure the robotussin you buy only has dextromethorphan (dxm) in it, if it has other ingredients dont take more than the recomended dose or you could die. You should take like 4 ounces to to have a pretty mild trip, so either take an entire 4 ounce bottle or half of an 8 ounce. warning you proberbly will puke a little but youll survive. 3 times the recomended dose wont do shit you need at least 4 ounces. it tastes nasty so i usually chug it dont take shots. good luck.