Cocaine

How it works:
Blocks dopamine uptake in brain's neurotransmitters, stimulating "pleasure nerves".

How it feels:
Rush of euphoria, energy, confidence, talkativeness, followed by a "low". 
Suppressed pain and appetite.

How it hurts:
Increase heartbeat, respiration, depression, paranoia.
Can induce heart attack, stroke, psychosis, coma.

How to get help:
Psychiatric Institutes of America, 1-800-COCAINE