The human body and brain are laden with opioid receptors, which link up biochemically with naturally occurring pain-killing opiates known as endorphins. Endorphins are also produced during vigorous exercise and are known to induce pleasurable feelings. Heroin resembles the body’s natural opioids but is far, far stronger and vastly more toxic. It attaches to the opioid receptors much more rapidly than endorphins and produces immediate and intense feelings of euphoria – a major cause, in fact, of recurrent use and subsequent heroin addiction. Heroin is known to be an especially addictive opiate drug.
The euphoric effects of heroin are considered by many who use it to be one of the most positive effects of the drug. However, it drives an often-compulsive search for repeated pleasure-highs, while simultaneously producing neurochemical changes in the brain that push users to seek higher and higher doses. This ever-increasing tolerance is one of the more toxic effects of heroin addiction and increases the danger of lethal overdose.
The quest for repeat experiences of euphoria becomes a form of malignant seduction, as if the drug is constantly calling the increasingly addicted user to get more and more, higher and higher. Between highs, addicts typically feel physically unwell, despondent, numb and dejected, with the result that the most destructive consequence of heroin addiction is the intensification of the addiction itself and the diminution of pleasure. Addicts frequently find that the over-riding priority of their lives becomes obtaining the next “hit” of heroin, and they become highly vulnerable to recruitment into a life of crime in order to feed the addiction.