Physiological Effects: Heroin



Heroin is an opioid like drug that affects a vast amount of not just the brain, but the body as well. In the 1800’s opium was brought to America by China and became popular quickly. Opium led to the creation of a new drug called morphine. Because of morphine’s ability to block pain, it was widely given out by doctors to those who had just had surgery. When people realized how highly addictive morphine is, they searched for a new drug that has the same affects as morphine, but without the addiction. Scientists then discovered a way to create a new drug from morphine. They did this simply by synthesizing morphine into something entirely new. This was done in the hopes of creating a wonder drug that had all the positives of morphine but none of the negatives. When morphine is synthesized, the result is what is known as heroinHeroin in the Synapse. Heroin became that new drug for doctors. Unfortunately, the addictive qualities of heroin are worse than those of morphine.




Heroin can enter the body in many different ways. The most common form of use is injection. The typically white or brown powdery substance is burned in some way and turned into a black tar like substance; this is where the term “black tar heroin” comes from. That substance is then put into a syringe and injected into the bloodstream. Other than injection, heroin can be inhaled from being smoked, or even insufflated. These methods are not as common as injection but have been reported as being used. It is because of these methods that someone who is using heroin may possess: burnt silver spoons, burnt straws, and needles or syringes for non-medical purposes.



Besides the areas mentioned in the previous section, heroin touches on many other parts of the brain. One area heroin affects is the limbic system. The limbic system deals with basic human emotions. When an individual feels an emotion such as anger, pleasure, happiness, etc. it is because the limbic system is being used. Because heroin is a drug that stops pain and brings immense pleasure, it is not surprising that the limbic system is highly involved in its use. The cerebral cortex is also affected by heroin. This part of the brain deals with consciousness. When heroin is used. The cerebral cortex isn’t able to keep that person as conscious as they should be.

Another key part of the brain that this drug affects is the somatosensory cortex. This system is the reason people are able to feel touch or physical pain. As stated previously, heroin shuts down the part of the brain that senses pain. The way it does this is by making this cortex unable to function the way it is supposed to. This is also why someone who has used heroin is unable to feel not only pain, but touch as well. In addition, the brain stem suffers when heroin is in the body. This is a large problem because the brain stem is responsible for highly important functions. The brain stem controls respiration, arousal, and controlling blood pressure.

Heroin use changes the way the individual breathes by either speeding it up or slowing it down. Rapidly changing the amount of oxygen the brain gets can lead to hypoxia, which can have long term affects including the physical change of the brain or brain damage. Heroin also slows the heart rate, which will lower one’s blood pressure. If one’s blood pressure is too low it could result in unconsciousness or even death. Unfortunately, heroin also makes the user extremely aroused, which is part of that pleasurable rush that a user will feel.



Once heroin enters the body, it has an immediate effect. Those who use heroin are said to experience a rush shortly after the drug has entered their body. This rush is produced because heroin affects several different parts of the brain. Heroin follows the reward pathways. These pathways flow throughout most of the brain, but are abundant in ventral tegmental area, the nucleus accumbens, and the prefrontal cortex. The reward pathway is what allows for pleasure, which is where the rush comes from. Heroin activated these pathways because it has the ability to bind to opioid receptors, which are the body’s natural pain blockers. When opioids produced by the body attach to their receptors, it is to block an individual’s ability to feel pain. Natural opioids are produced when the body is in physical pain. When heroin binds to these receptors, the individual not only will feel no pain, but because there was no pain present when the drug was injected, they also end up receiving pleasure from the drug.



It’s clear that heroin largely affects the brain, but it also affects the body as well. Immediately after use, someone who has used heroin may experience warm or flushed skin, dry mouth, heavy extremities, nausea, vomiting, and itching. Nausea andvomiting may be worse for someone who is using heroin for the first time, because the body is not used to the substance so it will try to reject it. Dry mouth comes from the rapid change in breathing. The most obvious immediate side effect is the heavy extremities because heroin slows heart rate and consciousness, so doing something simple like lifting one’s arm may be quite challenging when the drug is in the body. There are also side effects after heroin has been in the system for a few hours.

As mentioned previously, the heart rate will slow and respiration will change, but these are not the only effects. Many who use heroin will report clouded mental function, drowsiness, and convulsions. Heroin will also have long-term effects on the bodyand the brain. Those who have been using for a long period of time are putting their health and their lives in danger. Deterioration of white matter in the brain occurs after chronic heroin use. The white matter in the brain is involved in decision-making, the ability to regulate behavior, and the ability to respond to stressful situation. The body will also begin to adapt to heroin constantly being in the system, which makes the drug much harder to quit.

Because the body adjusts to the drug, when the drug is no longer there the body begins to go through withdrawal. Another long-term effect is collapsed veins. This means that blood will not be able to circulate through the body the way it is supposed to. This can indirectly lead to infection of the heart lining. Along with these side effects, heroin allows for the possibility of disease. The use syringes can expose an individual to diseases such as HIV and Hepatitis C.



Many times, those who are addicted to drugs would prefer to deal with the long-term effects of heroin as opposed to the withdrawal symptoms. The withdrawal symptoms that come after quitting heroin include cold sweats, nausea, vomiting, depression, anxiety, unstable mood, muscle cramping, and in severe cases seizing. Depression and anxiety can be the result of heroin withdrawal is because the reward pathways are no longer being activated in the way they were before. Heroin over works the reward pathways so when it is not present in the system and the body returns to a state of homeostasis, the individual feels much lower than they are used to, which leads to depression. The same goes for anxiety. Heroin makes the individual feel sedated and calm, so when the drug is no longer present, the individual feels much more on edge than they became used to.


Written and Research Conducted by: Cassandra Griffiths