Effects of Heroin on the Brain

Effects of Heroin on the Brain

The drug impacts a wide range of areas of the human brain, leading to a list of short- and long-term effects that are both shocking and dangerous. Individuals can experience reduced respiratory function, a condition responsible for many overdoses, as a result of the brain not consistently sending signals to other parts of the body. It also leads to digestive problems as signals to the bowels fail to fire, giving rise to constipation. Individuals using heroin often experience severe mood swings, and loss of appetite is common. Brain damage can occur after years of steady consumption.

Opioid Receptors

Opiates such as heroin act on a number of receptors that the human brain uses to recognize and deal with pain. For this reason, this class of drugs has long been a resort for doctors and patients in trying to cope with pain management. Opiates also have a tendency to influence signals that control a variety of involuntary bodily functions, such as breathing, heart rate and sleep cycles.

The brain itself releases a certain amount of natural opiates. One problem that occurs in people with drug habits is that an outside supply of opiates reduces the brain’s need to generate more, leading to an irregular cycle of ups and downs as the body fails to regulate itself properly. This can increase dependency issues as the brain requires outside input in order to achieve the same pain-reducing and function-regulating benefits it was previously able to manage naturally.


As is the case with many types of addictive substances, the brain releases dopamine, a chemical that drives the human impulse to seek anything needed for its survival. Dopamine release regulates a variety of positive sensations from maternal bonding with newborns to the friendship bonds between family members. It also can drive the impulse to eat, drink and do drugs. The release of dopamine that occurs when someone gets a hit of heroin can reinforce the process of becoming dependent upon it.

Brain Damage

Prolonged heroin use is associated with several distinct kinds of brain damage. One of the more disturbing issues arises from types of encephalopathy, diseases where the brain begins to break down at a molecular level. In extreme untreated cases, the user can suffer such a total breakdown of the brain’s integrity that the condition becomes lethal.

The rise of cases of individuals inhaling heroin has led to increased reports of people suffering brain damage. These cases tend to be notably worse than what is seen with individuals who snort or inject the product. Researchers believe that the toxicity of the compound is significantly increased by the molecules being burnt before they enter a person’s system. More concerning, inhaling heroin appears to be the fastest-growing way of doing the drug.

Gray and White Matter

Both white and gray matter areas of the human brain undergo significant alterations when exposed to heroin. White matter influences the way the mind perceives spatial relationships, and gray matter underpins almost all other functions within the brain. There’s still some scientific disagreement about how much destruction is caused in the white and gray matter of the brain, but the consensus is that regardless of the extent of the damage, none of it can be good.

The brains of a number of intravenous heroin and methadone users were examined after they had died. All of the subjects died relatively young, with an average age of 26 years old. The brain damage discovered was considered to be consistent with brains that had aged radically. Individuals were found to have indications of the early onset of Alzheimer’s syndrome. They were also found to be three times more likely than people of similar ages to have brain damage.

Among the more concerning findings is that these people experienced buildup of proteins and low-level inflammation in their brains. Subjects were also found to have indications of breakdowns in nerve cells, suggesting that damage goes far beyond the brain.


An especially insidious aspect of the effect of heroin on brain functions is the tendency of the drug to rewire the human mind. The brain actually begins to form more opioid receptors, giving rise to a cycle where it takes more of the drug to actually interact with the newly generated receptors. This can cause individuals to rapidly develop tolerances. More drug use begets more receptor generation, which begets more drug use, leading to an endless loop of increasingly dangerous self-dosing.

Because dopamine levels spike when heroin is consumed, the process also hijacks the entire reward-seeking system. As tolerances build, the amount of the drug that’s needed to generate a meaningful dopamine release also goes up. This reinforces cravings, and it can make periods without the drug seem especially crushing for people to deal with. Users often report feelings of emptiness and despair when they go without the drug for more than half a day.

One thing that worries drug counselors is that the difficulty in getting a satisfying high that accompanies a developed tolerance can cause people to try more aggressive delivery methods. Someone who was once happy taking a hydrocodone pill might start shooting heroin. As they climb the ladder of tolerance, users may eventually arrive at IV usage or even inhaling heroin.

Effects of using Heroin

An array of sensations accompanies the use of heroin, including feelings of sleepiness, a drop in body temperature and a loss of sex drive. Individuals using the drug will also experience a narrowing of the pupils. The overall feeling is a sense of tranquility alongside a general haziness. A sense of terror can also take hold if it has been several hours since someone has gotten their last fix.

Social withdrawal is especially common among people who use the drug. They often struggle to engage in activities outside of drug use. It’s also normal for them to focus on relationships with individuals who enable or facilitate the acquisition of more opiates. A loss of consciousness is typical, and this can cause individuals to make preparations to be alone or only with people they trust to not interrupt them.

Cognitive function tends to be significantly diminished. This does not appear to be as direct a product of immediate brain interactions as are seen with other drugs such as alcohol. The decline in cognitive ability tends to be the product of the general lethargy that follows when the brain stops aggressively sending signals to other parts of the body. Long-term brain damage will lead to a decline in cognitive capacity, too.

Blood Clots

Although not directly caused by the effects of heroin on brain processes, blood clots can pose major health risks for those who consume heroin. This is a product of the fact that those who shoot up do damage to a number of veins. As veins heal and collapse, this can give rise to clotting around the affected areas. Clots can and do break loose, and this can lead them to travel to the brain with the final result being the onset of a stroke.

Given that the brain of a drug user is already compromised in other ways from interactions with the drug, a stroke poses an elevated risk of leading to brain damage and permanent paralysis. People who are consuming heroin are often in no condition to respond to a stroke occurring, and police frequently report that individuals present at the time a person has a medical emergency will leave them behind in order to avoid potential prosecution. Social isolation also means that more of those who have strokes are alone at the time.

Mixed Drug Use

Researchers face hurdles trying to fully link heroin consumption to certain forms of brain damage because of mixed-used cases, especially with people who take alcohol or cocaine. Cocaine consumption is especially common in heroin users who are attempting to pull themselves out of the depressing and deep lows that opiates often trigger. Both alcohol and cocaine have been linked to brain damage, and they may have compounding effects on the already dire effects of heroin on brain tissues.

The Withdrawal Process

Once an individual has gone off the drug for about 12 to 30 hours, the brain and body will begin to crave it. The two symptoms that people tend to notice the fastest are agitation and insomnia. Anxiety can set in, and many people report feeling muscle aches and even pain down into their bones. They’ll also begin to feel a massive craving for the drug.

A number of neurological responses follow from getting off heroin. The term “kicking the habit,” for example, is believed by some to be related to neurologically triggered leg kicks that occur when people abandon the drug. The return of signals from the brain to other parts of the body can lead to some upsetting effects, such as diarrhea caused by function slowly returning to the digestive tract.

One fortunate aspect of withdrawal among all drugs classed as opiates is that there are no reported cases of direct deaths from going off them. While the sensations of withdrawal can be challenging to cope with and may last for weeks, people who quit heroin don’t face the same lethal risks that those who have stopped using alcohol or benzos do. For individuals who have the capacity to tough it out, quitting cold turkey, while not generally recommended, is a possibility.


Based on the extreme needs that many heroin consumers have to relapse, attempting recovery in the absence of professional support can be difficult. The drug demands a regimented approach to recovery, and this can be complicated by the legitimate pain management concerns of those who moved from opiates to heroin. In light of the radical brain damage that can occur as a result of consuming the drug, the sooner someone initiates the recovery process, the better.

The aggressive rewiring of the brain that occurs during heroin consumption means that those looking to restore their health should not be discouraged by relapses. While many people can be weaned onto other classes of drugs, such as methadone, the call of heroin tends to be strong. The important thing for those looking to support friends or family members in the process is to be understanding of the challenges that come with it.

Arrow Passage Recovery is here to help anyone struggling with heroin addiction. Do not hesitate to call us, we’re available 24/7 to take your call.

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