Dopamine is a biochemical,and occurs bodies of living things, dopamine is one of the chemicals responsible forrunner's high.
But you can 'take' dope, by consumption of drugs like marujuana,which make you high by raising your dopamine levels.
Though it is possible to get unadulterated dope,it's very difficult, and worth a fortune, and though it won't harm you.
(1. you won't come across it often enough to get very addicted. 2.Addiction is the only recorded bad side-effect, but too much in one go will probebly kill you, anything can, even air.)
It's probebly illegal because it's urgently needed for treatment of patients in hospital.
If you take dope, your body will not be able to make it anymore,but it's essential to your emotional wellbeing and the workings of your nervous system, so if your quitting please get professional help.