Heroin

Any condition reducing baseline respiratory function (COPD, severe asthma, sleep apnoea, obesity hypoventilation syndrome) represents an absolute contraindication to unsupervised opioid use. Respiratory depression is the primary lethal mechanism of heroin overdose.

Sleep apnoea patients face compounded respiratory depression risk as opioid CNS depression overlaps with apnoeic episodes.

Head injury with possible raised intracranial pressure is an absolute contraindication. Opioid effects worsen ICP and obscure clinical monitoring parameters.

Pre-existing psychiatric conditions (depression, PTSD, personality disorders) are major risk factors for rapid transition to heroin dependence. Anxiolytic and euphoric effects serve as reinforcement for psychiatric distress.

Severe hepatic impairment slows morphine clearance and M6G accumulation, effectively increasing opioid exposure from repeated doses.

Heroin use during pregnancy produces 6-fold increased obstetric complications, neonatal withdrawal syndrome, and 74-fold increase in SIDS. Classified as relative because abrupt cessation carries fetal risk; managed OAT is the clinical standard.

Active use of any CNS depressant represents an absolute contraindication due to synergistic respiratory depression — the most common pharmacological contributor to heroin overdose death.

Following incarceration, hospitalization, or voluntary abstinence, tolerance loss makes previously tolerated doses potentially lethal. Overdose deaths increase >7-fold in the first two weeks after prison release.