Heroin, known more formally as Diacetylmorphine, is a semi-synthetic opioid ester derived from morphine which in recent years has played a large role in precipitating the “Opioid Crisis” in America. This is in part due to the large number of highly addictive opioid painkillers which were heavily prescribed beginning in the mid-1990s and early 2000s.
Being cross-tolerant to heroin, any user who was addicted to prescription painkillers could use heroin to produce the same euphoric and analgesic (pain suppression) effects and to stave off withdrawal. This is compounded by the fact that heroin is typically cheaper per dose than any prescribed opioid, prompting a migration from prescription painkillers towards heroin.
Overview of Heroin Effects
Heroin acts a general Central and Peripheral Nervous System depressant. Depending on the route of intake, heroin can have very different and distinct intensities and durations. For example, when eating heroin it will be broken down completely into morphine through first-pass metabolism and will not produce the same intensity or depth of euphoria typically associated with heroin use. This will result in the same effects as if you had taken a pill of morphine. On the other hand, smoking heroin seems to produce the same type and intensity of high as an injection, however, the onset of euphoria is delayed slightly. As far as the effects of snorting heroin, there have not been many controlled studies done with this intake method, but anecdotal evidence seems it is similar in effects to IV use, but much less intense and stretched out over a longer duration.
When you use heroin by shooting it up it will be broken down in the brain, liver, and kidneys into several different metabolites, the most reactive of which are 6-Monoacetylmorphine (6-MAM) and morphine with the conjugates Morphine-6-Glucuronide (M6G) and Morphine-3-Glucuronide (M3G)¹. It should be noted that heroin itself is biologically inactive, and acts as a prodrug delivery system for its more active metabolites like 6-MAM and morphine. Once delivered into the brain, these metabolites bind to opioid receptor sites (most importantly the μ opioid receptors) and this is the primary mechanism of action for the effects produced.
Short Term Effects of Heroin Use
Heroin can be thought of as a supercharged version of morphine. Due to their chemical structure, morphine-derived esters like heroin are able to penetrate the blood-brain barrier much more rapidly (about 10 times faster) than morphine itself and are thus much more immediate and potent in their effects¹. Once in the brain, heroins derivative metabolites bind to the μ (Mu), δ (Delta), and κ (Kappa) opioid receptors and act as an agonist (an activity or function promoter).
To get an idea of what makes heroin so potent, let’s look at the proper name of heroin for some insight: di (2) acetyl (methyl/carbonyl group) morphine (primary drug). This simply means that heroin is morphine with 2 added acetyl groups. Acetylation is commonly used in organic chemistry to increase the penetration capability of a drug across the blood-brain barrier. This means that the acetyl groups allow a large amount of heroin into the brain very quickly. Once heroin is in the brain, metabolism will remove the acetyl groups and morphine (and its metabolites) will be left free to bond to the opioid receptors in the brain. Because of the speed heroin can enter the brain there will be a surge of morphine delivered in a single dose and massive activation of the opioid receptor sites. This is much more powerful than taking morphine alone and has the subjective effect of feeling like an intense rush of euphoria, relaxation and warmth, pain reduction, and a sense of wellbeing.
Heroin produces its effects very quickly regardless of the route it is taken, but for now, we will focus on the IV route. When injecting heroin, the effects felt are almost immediate. Some of the direct physical symptoms that are produced include:
- Slowed Heart Rate
- Depressed Breathing
- Constricted Pupils
- Hoarse Voice (due to dry mouth and throat)
- Pale or Grey Skin
- Nodding Off (brief lapses in consciousness which look like mini naps)
- Clouded or Slow Thinking
- Extreme Itchiness
- Decreased Appetite
- Vomiting (this happens often with some people, and rarely with others)
Someone who has recently used heroin may also be easily agitated or irritable. Heroin users often describe feeling as if someone is “killing their high” when they are interacted with while they are high. A user will also appear very tired or as if they are thinking and moving in slow motion. They may also “nod off” while sitting, standing, or in the middle of performing a simple task. They may awaken after a second or they may slowly relax until they jolt themselves awake by losing their balance.
These effects may last from an hour or two when injected and typically slowly return the user to full consciousness within 4 or 5 hours of use. As tolerance builds with repeated use, the effects felt will weaken as will the length of time the high lasts. Likewise, the feeling of being sober will increasingly feel uncomfortable and unpleasant as the body and brain adapt to the presence of heroin, and withdrawal symptoms begin to manifest.
Long Term Effects of Heroin Use
One of the more dangerous effects of long term heroin use is the buildup of tolerance. This means that the brain and body have adapted to the presence of heroin through a process called downregulation and more heroin is needed to produce the same effects. This begins to happen very early in the stages of heroin use and only escalates as more heroin is used. The development of tolerance also means that someone will feel increasingly uncomfortable without heroin and is on the way to dependence and finally addiction. It is possible that after using heroin for long enough, a user’s body may never return to the tolerance levels they had before using heroin. This means that any opioid painkillers that they may need for serious issues will be less effective.
The effects heroin has on the body and mind are far-reaching and won’t be fully felt until it has been used for extended periods of time. There is, of course, the fact that heroin use will produce physical dependence and addiction if used for an extended period. There are also physical symptoms that will take time to produce consequences, but often by the time the consequences are noticed it is too late to do anything except damage control. Some of the more common symptoms of this type include:
- Chronic Constipation: This is unpleasant on its own and may lead to a prolapse, impacted stool, and other GI issues.
- Tooth Decay: Due to chronic dry mouth as well as decreased focus on personal hygiene.
- Reproductive Dysfunction: In men heroin can interfere with the ability to orgasm and in women, it may cause menstrual abnormalities.
- Malnutrition: Chronic low appetite can lead to a host of other issues precipitated by malnutrition as your body is consistently depleted of resources.
- Insomnia: While “nodding off” is common, actual REM and deep sleep can become difficult after prolonged heroin use.
- Compromised Immune System: Due to malnutrition, decreased metabolism, and repeated injection or snorting wounds.
- Respiratory Disease: Heroin addicts are known to suffer a higher incidence of lung-related health issues such as pneumonia.
- Decreased Ability to Manage Pain: Due to tolerance, other painkillers won’t work as well if and when they are needed for injuries, surgery, etc.
- Increased Anxiety: Many addicts suffer from intense anxiety during periods of unwanted sobriety.
- Increased Depression: An addict’s primary goal is to get high. With this being the only thing to look forward to, motivation for other activities is almost nonexistent.
- Increased Risk of Organ Damage: IV drug use poses a unique risk for many organs such as the heart, lungs, kidney, liver, and brain.