As arule of thumb, it is profoundly unwise to take crack-cocaine. The brain has evolved atruly vicious set of negative feedback mechanisms. Their functional effect is to stop us from being trulyhappy for long. Nature is cruelly parsimonious with pleasure. The initial short-lived euphoria of a reinforcer as uniquely powerful as crack will be followed by a "crash". This involves anxiety, depression, irritability, extreme fatigue and possibly paranoia. Physical health may deteriorate. An intense craving for more cocaine develops. In heavy users, stereotyped compulsive and repetitive patterns of behaviour may occur. So may tactile hallucinations of insects crawling underneath the skin ("formication"). Severe depressive conditions may follow; agitated delirium; and also a syndrome sometimes known as toxic paranoid psychosis. The neural aftereffects of chronic cocaine use include changes in monoamine metabolites and uptake transporters. There is down-regulation of dopamine D2 receptors to compensate for their drug-induced overstimulation. Thus the brain's capacity to experience pleasure is diminished.
The social consequences of heavy cocaine use can be equally unpleasant. Non-recreational users are likely eventually to alienate family and friends. They tend to become isolated and suspicious. Most of their money and time is spent thinking about how to get more of the drug. The compulsion may become utterly obsessive. The illusion of free-will is likely to disappear. During a "mission", essentially a 3-4 day crack-binge, users may consume up to 50 rocks a day. To obtain more, crack addicts will often lie, cheat, steal and commit crimes of violence. Once-loved partners and children may be callously cast aside. Whole communities can be disrupted by crack-abuse. Whereas "empathogens" such as MDMA / Ecstasy - which trigger the release of more serotonin than dopamine - will typically promote empathy, trust, compassionate love and sociability, "dopaminergic" drugs such as cocaine or amphetamines, if taken on their own and to excess, can easily have the reverse effect. This story has complications - cocaine's affinity for the serotonin transporter is actually greater than for the dopamine transporter. But simplistically, cocaine tends to be a "selfish" drug.