KEY TAKEAWAYS
Heroin addiction:
Defining Heroin Addiction
Physiological Indicators Of Heroin Addiction
Dermatological And Circulatory Systems
Injections of black tar heroin are 7.68 times more likely to result in injection-site abscesses than injecting white powder heroin [2].
Liver damage is evident in active use when skin begins to bruise easily and show discolouration.
Bruising occurs at injection sites when a site is used more than once or the needle has not penetrated the vein correctly, causing it to hit smaller blood vessels surrounding the vein.
Histamines released during active addiction cause itching in 2-10% of opioid users [3].
Respiratory and Ophthalmic Symptoms
0.1mg/kg dose of heroin causes a 30% decrease in blood oxygen from baseline 1 minute after drug administration, resulting in blue lips [4].
Doses of 0.2mg/kg of heroin result in a 50% decrease in blood oxygen and last around 20 minutes, evidencing substantial hypoxia [5].
Injection use of heroin causes shallow breathing and respiratory depression, resulting in hypoxia.
Combining heroin with fentanyl increases the hypoxic effects 5-fold compared with heroin alone, evidencing the danger of mixing heroin with other substances.
Activating peripheral mu receptors in the respiratory network suppresses breathing by decreasing wakefulness.
70-140 neurons in the respiratory centre in the brain are responsible for the 50% reduction in ventilation in heroin use [6].
Typical use causes pinpoint pupils regardless of the route of administration.
Gastrointestinal And Autonomic Nervous System Effects
Heroin injections reduce mast cell counts by 23.1%, resulting in anaphylactic reactions and itching [7].
Heroin use causes the small intestine to thicken, making users 2.77 times more at risk of developing fibrosis [8].
As the substance binds to mu receptors, gastrointestinal motility is inhibited, resulting in mild to severe constipation in opioid-dependent patients.
21 days of use disrupts the gut microbiota, leading to constipation, pain, and an inability to digest food adequately.
Neurological Effects
Over 50% of active heroin use the drug as a sedative as it slows neuronal activity, leading to drowsiness.
Intravenous consumption of heroin converts to 6-monoacetylmorphine (6-MAM), leading to rapid absorption in the brain due to increased permeability (68%) across the blood-brain barrier compared to methadone (42%) [9] [10].
As the substance converts to morphine in the body, sedation occurs due to the inhibitory effect of the GIRK channels (~54%), therefore inhibiting GABA and glutamate [11].
Psychological Indicators Of Heroin Addiction
Mood Disorders And Emotional Dysregulation
The dopamine metabolite homovanillic acid is reduced by 33% in active users, resulting in depression and sleep disturbances [12].
Depression is more likely to occur in female users (35.2%) than male users (17.3%) due to gender differences in emotional processing [13].
Users have less than half the volume of BDNF protein in the brain, resulting in sensitivity to stress-induced anhedonia.
Users show brain volume reductions in the nucleus accumbens in both the shell (39%) and the core (42%) [14].
Reduced functional connectivity in the nucleus accumbens accurately predicts depression in 74.7% of users [15].
Cognitive Impairments And Memory Loss
Self-administration of heroin reduces neurogenesis in the hippocampus by ~42%, leading to brain fog and memory loss [16].
Users show a 17.7% reduction in letter and verbal fluency compared to controls [17].
On spatial memory tasks, users make 94.5% more errors than controls and 13.3% more errors than amphetamine users [17].
Combined use with fentanyl doubles the risk of cognitive impairments.
Distorted Perception and Paranoia
The average user's score for paranoia on the Brief Symptom Rating Scale is 1.7, compared to 0.9 for controls [18].
Paranoia is caused by a 13.4% reduction in dopamine D2 receptor availability during active addiction [19].
Pre-existing psychosis causes a 9.43 times increased risk of consumption, in turn worsening symptoms of paranoia [20].
Behavioural Indicators Of Heroin Addiction
Users will surround themselves with other users and may neglect any previous friendships to hide heroin misuse.
Weekly average use is higher when family members are unaware of drug use, so active avoidance of family members may indicate that opioids are being used.
Users lack personal grooming habits because the sedative effects of the drugs cause users to be unaware of appearance.
The sedative effects cause users to lose track of time and miss necessary appointments, such as medical checkups.
Users are likely to engage in risk-taking behaviours to consume the drug, with 22% sharing syringes for injection.
Cycle Of Heroin Addiction
Stage Of Heroin Addiction | Behaviours |
|---|---|
Initial Use | Drowsiness for 3-5 hours Disorientation |
Increased Use | Itching Skin picking Agitation and irritability |
Cravings | Stealing needles, syringes and tourniquets Needle sharing |
Dependence | Using every 6-12 hours to negate withdrawal symptoms Suppressed appetite and food-avoiding Hiding injection marks from family Keeping heroin-related paraphernalia |
Attempts To Stop | Cravings after 12 hours of non-use Mood swings and active frustration Hyperactivity and restlessness |
Withdrawal Symptoms | Yawning Runny nose and tearing Goosebumps Fever/chills Nausea and vomiting |
Relapse | 80-95% following sobriety |
Health Complications Of Heroin Addiction
Blood Borne Diseases
22% of users share needles, resulting in 40-80% contracting HIV through sharing equipment [21].
15-45% of injection users contract HIV through unprotected sex with other injection drug users [22].
74.5% of users have been exposed to over one risk factor for contracting HIV or Hepatitis B/C, such as not cleaning injection tools and severe dependence [23].
Respiratory Infections
1-3% of active users who overconsume heroin develop noncardiogenic pulmonary oedema, with up to 1% developing pneumonia, both causing death in worst-case scenarios [24].
100mg of the pharmaceutical variant causes blood oxygen levels to decrease to 89.3%, indicating pneumonia [25].
31.3% of hospital admissions for respiratory problems show aspiration of gastric contents, resulting in inflammation and infection of the lungs [24].
Brain Diseases
Leukoencephalopathy has a mortality rate of 25% and is caused by "chasing the dragon", a way of inhaling heroin through vapour heated on aluminium foil.
Ischemic neuronal damage is evident when users have experienced respiratory depression as a result of heroin use.
Cardiac Complaints
Use reduces cardiac output of the heart's right ventricle by 23.1% compared to non-users [26].
The isovolumic acceleration of the left ventricle is 16.4% slower in heroin users than non-users, leading to impaired left ventricular function [26].
10% of injection users develop staphylococcal infections, resulting in endocarditis in 85% of right-sided heart cases [27].
Emboli from injection drug use are caused by vascular damage or contracting Streptococcus.
Liver Disease
Serum levels for the liver enzyme ALT are 46.7% higher on average in users than in non-users [28].
0.5-1 gram of use results in AST liver enzyme levels 43.0 [29].
5-6 grams results in AST liver enzyme levels 108.6 [29].
Misuse for 5-6 years increases the risk of developing liver disease by 148%, compared to using for 1-2 years [29].
Abscesses And Infections
1 in 10 injection users contract staphylococcal infections, resulting in a painful rash and blisters; however, any infections are typically managed with antimicrobial treatment.
Injecting into the neck arteries results in skin abscesses that require soft tissue radiographs to assess damage.
Chronic abscesses are caused by vertebral osteomyelitis following 4+ years of intravenous use.
Overdose
Taking an excess dose leads to respiratory depression and brain damage as tissues become starved of oxygen.
Overdose causes overexcitation of dopamine receptors, resulting in intense euphoria, while the overexcitation of opioid receptors causes the autonomic nervous system to shut down.
As the autonomic nervous system begins to shut down, breathing becomes shallow and less frequent (<12 respirations/minute), resulting in hypoxia.
Injecting leads to a 15.9 times increased risk of intoxication compared to other routes of administration, resulting in fatal respiratory depression occurring quicker [30].
Legal Frameworks Of Heroin Addiction
As a Class A drug, possession, supply, and production are illegal in the UK; however, having an addiction or accessing treatment is not illegal.
Needle exchange programmes reduce the number of infected needles by 21%, making it an effective strategy to reduce HIV transmission.
The UK's first supervised injection room opened in Glasgow in 2023; however, these facilities are not available in every city.
Although injections are supervised in consumption rooms, smoking the drug is not permitted due to anti-smoking legislation and practical difficulties with appropriate ventilation in these facilities.
Vulnerable Groups
Vulnerable Group | More/Less Likely To Develop Heroin Addiction | Why? |
|---|---|---|
18 - 25 years olds | More likely | Risk-taking behaviour Peer pressure |
Homeless Individuals | More likely | |
Offenders | More likely | Heroin availability due to criminal network Heroin use in prison |
Individuals With Chronic Pain | More likely | |
History Of Physical, Emotional Or Sexual Abuse | More likely | Self-medicate trauma with heroin |
What Changes Heroin Addiction
Method Of Usage
Inhaling through chasing results in 26% being detectable in urine compared to only 14% being detectable by smoking [31].
Injection use leads to a 24.7% risk of HIV compared to snorting (12.7%), making it more likely to affect physical health [32].
20% of HIV cases are undiagnosed, making sharing infected needles particularly dangerous in active addiction.
Bipolar Disorder
55.6% of heroin users with co-occurring bipolar disorder self-medicate during depressive episodes [33].
The combination of depressive states and manic states changes addiction from periods of binge use during depression to periods of less frequent use during mania.
Erratic drug use in those with bipolar results in an increased risk of overdosing as tolerance levels fluctuate.
Personality Disorder
Personality disorder sufferers are less likely to access addiction treatment, allowing addiction to continue.
Borderline personality disorder sufferers with opioid addiction are 3.89 times more likely to attempt suicide, so the substance is used as a form of self-medication [34].
Co-occurring borderline personality disorder and addiction cause a 1.92 times increased risk of overdosing, resulting in long-term brain damage from hypoxia [35].
Eating Disorders
Binge eating disorder is 3.1 times more likely to occur in users, resulting in self-isolation that prevents treatment from being sought [36].
7% of opioid users have a lifetime history of anorexia and bulimia, substituting food with substance use [37].
Users with a history of eating disorders use it to suppress appetite and the perceived need for food.
Neglecting food throughout addiction results in long-term changes to health, such as malnutrition and vitamin deficiencies.
A co-occurring eating disorder with addiction intensifies cravings, resulting in more frequent use.
Heroin Being Mixed With Other Drugs
In 52% of concurrent opioid and benzodiazepine users, only one of the drugs was prescribed, and the other was sourced illicitly, evidencing that both act as gateway drugs [38].
Overdose is 1.2 times more likely to occur when benzodiazepines are taken for 5 days over 3 months.
40.3% of deaths relating to combined alcohol use have BAC levels ≥ 0.10 g/dL [39].
Contributing factors to polysubstance overdoses include longer time spent using, strong dependency and alcohol consumption.
The current global 95% reduction in the production and distribution of natural opioids is driving users to try synthetic variants, such as fentanyl, that are more potent and dangerous.
