Last updated : May 12, 2025
Derived from the long-used narcotic opium, heroin possesses even stronger mind-altering and addictive qualities than its predecessor. Given that this is accomplished by the drug from its interaction with opioid receptors in the body, it can be expected that the drug will physically affect the body. In addition, heroin has secondary means of inflicting physiological effects when it’s discontinued after the body has become accustom to it.
Basic Chemistry
To get an idea of heroin’s potency, it must be remembered that it was originally developed from opium by way of morphine. Opium has been used as a sedative drug for literally thousands of years. During the 19th century, chemists extracted morphine from opium as a pain-relieving medication. After discovering its highly addictive nature, diacetylmorphine or heroin was created as a hopefully non-addictive version of the drug. Instead, heroin proved to be even more addictive due to diacetylmorphine’s ability to pass from the blood stream into the brain faster than straight morphine. When used, the drug breaks down into morphine and 6-monoacetylmorphine, both of which bind to opioid receptors in the brain and elsewhere in the body like the nervous system and the gastrointestinal tract. The drug produces a mentally relaxed state and physical pain relief, but it quickly creates tolerance in the user.
Initial Response
The first physical responses to heroin use include constricted pupils, lower body temperature, dry mouth, and sleepiness. Due to its interaction with the nervous system, the drug also slows breathing and heart rate during which heart rate can also sometimes become erratic. Because of its activity in the gastrointestinal region, heroin also creates a feeling of nausea. With regular use, gastrointestinal interaction results in constipation. After the initial high wears off, a desire for more of the drug ensues due to a large number of opioid receptors being located in the pleasure/reward regions of the brain. In spite of this need, addiction doesn’t necessarily occur after the first use.
The Longer Term
With continual use, heroin can pose a threat through its bodily effects. The body inevitably becomes tolerant to each level of the drug and requires more to produce the same high. Behind the scenes, what’s actually happening is the brain responds to the excessive amounts of opiates by shutting down more and more opioid receptors, thus creating the increasing tolerance. Heavier doses can lower the heart rate to the point of cardiac arrest. In the case of the respiratory system, slower and weaker breathing can increase chances of pneumonia developing. Often, the nausea the drug produces can lead to death through suffocation by inducing vomiting while the user is unconscious, causing the air passages to become blocked.
Withdrawal
Because of the build-up of tolerance in the body’s opioid receptors, refraining from heroin use can cause withdrawal symptoms that center on pain and discomfort. Normally, everyday activities can trigger pain signals in the body. A healthy brain and nervous system can block these very low-level pain signals through the use of naturally-occurring endorphins on the opioid receptors. Since heroin overstimulates these receptors and even eliminates some of them, they won’t function normally when the heroin is taken away. Severe muscle, joint, and even bone pain are the result. With the opioid receptors in the gastrointestinal tract under-stimulated, constipation is replaced with diarrhea. Additional fallout from this process include chills, sweating, and insomnia.
