Although illegal, heroin use has made a comeback on the heels of the prescription opioid crisis. The National Institute on Drug Abuse (NIDA) advises that heroin is itself an opioid made from morphine, which, in turn, is derived from the opium poppy plant. Once taken, heroin hits the brain quickly and converts back into morphine before binding to opioid receptors that affect, among other things, pain, pleasure, breathing, sleeping and heart rate.

How Does Heroin Alter the Brain? explains that this binding action causes a powerful sense of both pain relief and euphoria. The body produces its own endogenous opioids, including endorphins, that have the same effects, but heroin is much more powerful. The pleasant effects from heroin are likely brought about by a flooding of dopamine that is triggered by the binding, and heroin releases up to 10 times the amount of dopamine released by the body’s own endorphins.

If that was as far as the process went, then perhaps it would be okay. Unfortunately, over time, continued use causes changes in the brain as it tries to adjust to the sudden and dramatic spikes in receptor and dopamine activity. The brain does this, in part, by lowering its threshold for pain tolerance, which means that the user will become less naturally able to handle pain and will need to use ever-increasing doses of the drug to get the same effect or even just feel normal.

Similarly, as explained by, as it gets used to heroin intake, the brain will effectively assume that this intake is the new normal, and it will compensate by cutting production of its own endorphins. This adjustment takes a drastic toll on the brain’s ability to function and experience pleasure normally, thus leading to withdrawal symptoms. These symptoms likewise trigger the user to continue using and increasing dosage, not only to get “high,” but to try to feel normal.

It can take surprisingly little time for these changes to start occurring, as there has been some suggestion that they could begin happening as soon as shortly after the first dose is taken. While heroin can be used by injection, sniffing, snorting or smoking, the drug will affect the brain differently depending on which route of administration is used. Intravenous injection and smoking are the fastest routes to the brain.

How Does Heroin Alter the Brain?

Long-Term Consequences

The Recovery Village notes that heroin impacts the parts of the brain that make up the reward pathways, including the frontal cortex, nucleus accumbens and ventral tegmental area. When people do naturally pleasurable things like have sex or eat a good meal, these are the components that work together to create the sense of pleasure. This process works in a way that is largely similar to using heroin or other illicit drugs but on a smaller scale.

With long-term use, heroin will start to impair the prefrontal cortex and temporal lobes, the parts of the brain that control memory, decision-making, self-control and higher thinking. Accordingly, once the damage has been done in these areas, users will experience problems with remembering, making sound choices, processing emotions, reasoning, solving problems and socializing. The symptoms of this level of brain damage are comparable to the early stages of Alzheimer’s disease, and users may even suffer from such visible problems as tremors. Although these symptoms normally come on with ongoing, chronic use, their onset can happen sooner than people expect and are not easily treated.


NIDA warns that heroin overdose can happen when so much of the drug is used that the reactions in the brain become life-threatening. Because the opioid receptors control such vital functions as breathing and heart rate, heroin or other opioid overdose triggers dangerous declines in the body’s ability to survive. Breathing, for example, can slow down or stop, thereby preventing sufficient oxygen from reaching the brain. Even if the user survives, this condition, known as hypoxia, can cause debilitating long-term effects, including coma and permanent brain damage.

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