Opiate addiction

Respiratory depression is the direct cause of death in opioid overdose and the most immediately life-threatening physiological consequence of opioid exposure. It represents the single greatest acute risk of opioid use.

• Opioids act on mu-opioid receptors in the brain stem’s respiratory control centres (the pre-Bötzinger complex and the nucleus tractus solitarius), reducing the sensitivity of these centres to rising carbon dioxide levels, the primary physiological trigger for breathing. The result is a slowing and shallowing of respiration that, in overdose, progresses to apnoea (complete cessation of breathing) and death.
• The risk of fatal respiratory depression is substantially elevated by the concurrent use of other CNS depressants, particularly benzodiazepines and alcohol, which produce synergistic respiratory suppression through independent mechanisms. This drug combination is responsible for the large majority of opioid overdose deaths.
• Tolerance develops to many of opioids’ effects with chronic use, but tolerance to respiratory depression does not develop at the same rate as tolerance to euphoria and analgesia. This creates a dangerous therapeutic window that narrows with escalating doses, and a period of particularly elevated overdose risk following any reduction in tolerance.
• Inhalation of heroin smoke or fentanyl vapour causes direct airway irritation and has been associated with increased rates of asthma, bronchospasm, and respiratory infection in people who use these routes.

• Opioids reduce heart rate (bradycardia) and lower blood pressure through their CNS depressant actions. In therapeutic doses this is generally manageable, but in overdose or in combination with other depressants, it contributes to cardiovascular collapse.
• Intravenous opioid use introduces the direct risk of infective endocarditis, a serious and frequently fatal infection of the heart valves caused by bacteria introduced through non-sterile injection. Endocarditis rates among people who inject drugs have risen sharply in the UK and represent one of the most medically serious complications of injection opioid use.
• Repeated injection causes progressive venous damage, thrombophlebitis, collapsed veins, and deep vein thrombosis (DVT), forcing users to access increasingly difficult and dangerous injection sites, and raising the risk of pulmonary embolism.
• Certain synthetic opioids (particularly methadone) are associated with cardiac arrhythmia through QTc interval prolongation, a clinically significant effect that requires electrocardiographic monitoring during treatment.

Opioid receptors are among the most densely distributed in the gastrointestinal tract, and opioids’ effects on the gut are among their most consistent, predictable, and clinically burdensome consequences:

• Opioids profoundly slow gastrointestinal motility, producing severe, chronic constipation. Prolonged constipation leads to faecal impaction, haemorrhoids, anal fissures, bowel obstruction, and in severe cases, bowel perforation.
• Opioid-induced bowel dysfunction (OIBD) encompasses a broader spectrum of GI symptoms including nausea, vomiting, gastric reflux, abdominal cramping, and bloating, arising from opioid effects on multiple levels of the enteric nervous system.
• Opioid-induced nausea and vomiting are particularly prominent during initial use and dose escalation, mediated by mu-receptor activation in the chemoreceptor trigger zone of the brain stem and by slowed gastric emptying.
• The severe diarrhoea, cramping, nausea, and vomiting of opioid withdrawal represent the acute rebound of GI motility and secretion following removal of opioid suppression, producing significant fluid and electrolyte loss that can require medical management.

• Opioids exert significant immunosuppressive effects through both direct action on opioid receptors expressed on immune cells (including T-cells, B-cells, and natural killer cells) and through indirect neuroendocrine mechanisms via the HPA axis.
• Chronic opioid use reduces natural killer cell activity, T-cell proliferation, and antibody production, impairing the body’s first-line defences against infection. This contributes to the elevated susceptibility to bacterial infections, respiratory illness, and reactivation of latent infections (such as tuberculosis) seen in people with opioid use disorder.
• For people who inject opioids, the immunological consequences are compounded enormously by direct pathogen introduction: HIV, hepatitis B, and hepatitis C are all transmitted efficiently through shared needles, and the UK’s population of people who inject drugs bears a disproportionate burden of these blood-borne infections.

• Chronic opioid use produces opioid-induced endocrinopathy, a comprehensive disruption of hormonal regulation mediated primarily through suppression of the hypothalamic-pituitary axis. Effects include suppression of gonadotropin-releasing hormone, leading to reduced levels of luteinising hormone and follicle-stimulating hormone, and downstream reduction of testosterone in men and oestrogen in women.
• In men, this hormonal suppression produces hypogonadism: reduced libido, erectile dysfunction, infertility, fatigue, mood disturbance, and loss of muscle mass. These effects are dose-dependent and have been documented with both illicit and long-term prescription opioid use.
• In women, opioid use commonly causes amenorrhoea (cessation of the menstrual cycle), anovulation, and impaired fertility, as well as mood disturbance and reduced bone density.
• Long-term opioid use is associated with significant bone density reduction (osteoporosis) through hormonal suppression and direct effects on osteoblast and osteoclast activity, substantially increasing fracture risk.
• Chronic pain and opioid-induced hyperalgesia interact in a clinically challenging way: the opioids prescribed to manage pain eventually increase pain sensitivity, creating a cycle of escalating opioid use and worsening pain that is difficult to unravel without specialist input.

• Hepatitis C (HCV), transmitted primarily through shared injecting equipment, is the most significant hepatic risk for people who inject opioids. Hepatitis C causes progressive liver inflammation that, if untreated, advances to cirrhosis, liver failure, and hepatocellular carcinoma. It is estimated that around 50% of people who inject drugs in the UK have been infected with hepatitis C at some point.
• Hepatitis B is similarly transmitted parenterally and can cause both acute hepatic injury and chronic liver disease. Vaccination is available and recommended for all people who inject drugs, though uptake remains suboptimal.
• Certain opioids, particularly buprenorphine and methadone in hepatically impaired individuals, require dose adjustment due to altered hepatic metabolism, and tramadol may have increased seizure risk in liver disease.

• Repeated intravenous injection produces characteristic and progressive venous damage: track marks, bruising, scarring, and ultimately complete venous collapse along injection sites, forcing progression to more dangerous injection sites including the neck, groin, and feet.
• Skin and soft tissue infections are among the most common medical complications of injection drug use. Abscesses, cellulitis, and necrotising fasciitis (a rapidly progressive and life-threatening tissue infection) arise from introduction of skin flora and environmental bacteria during injection, particularly with skin-popping or intramuscular injection.
• Wound botulism, caused by Clostridium botulinum spores in contaminated heroin, has been documented in injection drug users in Scotland and England, producing life-threatening neurological paralysis.
• Chronic neglect of personal care, nutrition, and hygiene associated with opioid addiction contributes to poor wound healing, skin breakdown, dental deterioration, and generalised physical deterioration.

A substantial body of clinical and research evidence supports the self-medication hypothesis as a key pathway into opioid addiction, the idea that opioid use begins as an attempt to manage pre-existing emotional pain, trauma, or psychiatric symptoms for which adequate help has not been sought or found. Opioids are extraordinarily effective short-term analgesics not only for physical pain but for psychological pain: they suppress the stress response, blunt emotional reactivity, and produce a temporary state of profound wellbeing and freedom from suffering.

For individuals living with unprocessed trauma, persistent depression, severe anxiety, or the chronic psychological pain of adverse childhood experiences, this effect can feel like the first genuine relief they have ever found. Understanding this does not excuse or minimise the harm of addiction, but it is essential for designing effective treatment, because without addressing the underlying reasons for use, recovery from opioid addiction alone is significantly less likely to be sustained.

Common co-occurring mental health conditions exacerbated or introduced due to opioid addiction are:

Depression

Opioid-induced suppression of the dopamine reward system and depletion of the endogenous opioid system produce a profound and persistent depression that is a near-universal feature of established opioid dependence. The anhedonia, motivational deficit, emotional flatness, and hopelessness of opioid-associated depression can persist for months into abstinence as the brain’s reward chemistry slowly recalibrates. This is one of the most powerful drivers of relapse: using opioids is the fastest and most reliable route back to feeling anything at all.

Post-Traumatic Stress Disorder (PTSD) and trauma

The co-occurrence of opioid use disorder and PTSD is exceptionally high. Traumatic experiences, childhood abuse, sexual violence, domestic violence, combat exposure, bereavement, are significantly overrepresented in the histories of people presenting for opioid treatment. Without treatment of the underlying trauma, the psychological pain that drove opioid use remains present and unresolved, making the prospect of abstinence, and the full felt experience of that pain, feel intolerable. Trauma-informed care is not optional in effective opioid treatment; it is essential.

Anxiety disorders

Opioid withdrawal and PAWS are characterised by profound and often disabling anxiety, a neurochemical rebound driven by locus coeruleus hyperactivity and HPA axis dysregulation. This anxiety frequently exceeds any pre-existing anxiety disorder in severity, making the acute withdrawal period extremely difficult to endure without support and creating a powerful incentive to return to opioid use as an anxiolytic. Generalised anxiety disorder, panic disorder, and social anxiety disorder are all common co-occurring conditions.

Psychosis

While opioids themselves are less directly psychotomimetic than stimulants or cannabis, the chaotic circumstances of severe opioid addiction, sleep deprivation, malnutrition, polysubstance use, and the neurological stress of repeated withdrawal cycles, can precipitate psychotic episodes. Opioid withdrawal delirium, while rare, is a medical emergency. In those with a pre-existing vulnerability to psychotic disorder, the neurobiological stress of opioid dependence may precipitate or accelerate onset.

Increased risk of suicide and self-harm

People with opioid use disorder face a dramatically elevated risk of death by suicide compared to the general population. The combination of profound depression, hopelessness, social isolation, trauma history, chronic pain, and the neurobiological impairment of the prefrontal cortex creates an environment in which suicidal thinking can develop, persist, and go unaddressed. Opioid overdose itself, whether intentional or accidental, is frequently the cause of death, and the distinction between the two is often blurred. Suicide risk assessment and crisis planning are essential components of any opioid treatment programme.

Yes, overdosing on opioids can be fatal, but only if the individual abuses the drug or doesn’t understand the risks of doing so. Misusing opiates carries the chance of overdose and death due to the effects it can have on the body.

Symptoms of opioid overdose include difficulty breathing, slowed or stopped breathing, extreme sleepiness, snoring, clammy skin, confusion and loss of consciousness. If you or someone you know exhibits any of these symptoms while taking opioids, seek immediate medical attention.

Opiate withdrawals typically last about 5 to 10 days, depending on factors such as the specific opiate used, duration of use, and individual physiology. Withdrawal symptoms generally peak within the first few days and gradually subside over a week or two. However, some individuals may experience lingering symptoms like anxiety or insomnia for several weeks or months after detox begins.

During opiate addiction treatment, you can expect a comprehensive approach that addresses both the physical and psychological aspects of addiction. Initially, there may be a detoxification phase to manage withdrawal symptoms. Following detox, treatment often includes behavioural therapies such as cognitive-behavioural therapy to help change addictive behaviours and develop coping strategies.