The University of Arizona

Health Consequences of Illicit Drug Use
Heroin Overdose

Overdose is a major cause of deaths in heroin users.  In contrast to amphetamines, the doses for recreational heroin use and the doses that cause death by respiratory depression have a small window of difference.  Also, overdose and death are more common with heroin use than any amphetamine use.[1] Risk factors that may instigate an overdose are discussed below.

Coexisting drug use

Using other sedative or stimulant drugs with heroin is associated with overdose mortality among heroin users.  In a study done in New York, the most common drugs that were taken simultaneously were opiates and cocaine according to autopsies.  Alcohol was also found to be widely used with heroin.[2]  By administering another depressant like alcohol with heroin, there is a greater chance of fatal overdose since the depressant effects of heroin can be further exacerbated.[3]

Prior abstinence or reduced use

Fatality due to overdose can result from periods of abstinence prior to the heroin administration; this may be due to reduced opioid tolerance.[2,3]  A study indicated that fatality as a result of overdose is a concern after heroin users are released from prison.  Between 1992 and 1996, 5% of heroin users died soon after release, of whom many died within 24 hours. This can be attributed to the fact that due to abstinence or infrequent use in prison, the opioid tolerance was reduced in prisoners, leading to more overdose fatalities.[3]  The risk of overdose also increased when treatment was stopped by a heroin user.  Adherence to treatment may reduce tolerance and a relapse may increase the risk of overdose.[2]

Systemic dysfunctions

Hepatic disease
Heroin users have a high risk for developing liver disease.  Those who develop liver damage due to chronic heroin use may have reduced opiate metabolism in their liver.  This can increase the period of heavy intoxication, thus increasing the risk of overdose.[3]

Pulmonary disease
Pulmonary dysfunction may also be associated with mortality from heroin overdose since respiratory arrest is the mechanism by which mortality often occurs.  Heroin users with reduced pulmonary function can have greater vulnerability to fatal respiratory depression, thus having an increased risk of overdose.[3]

Smoking tobacco is highly prevalent among heroin users.  Injection drug users are known to have bronchitis and other smoking-related respiratory conditions, suggesting induced pulmonary disease among heroin users, making them more susceptible to overdose.[3]

Respiratory Infection
Malnutrition and poor hygiene are common among heroin users, and this can lead to respiratory infections, which may increase the susceptibility of users to overdose.[3]

Some of the complications that may arise due to heroin overdose are:(3)

  • Pulmonary effects
    • Oedema
    • Pneumonia                                                       
  • Cardiac effects
    • Arrhythmia
    • Acute cardiomyopathy
    • Haemoglobinaemia
  • Muscular effects
    • Rhabdomyolysis
  • Neurological effects
    • Cognitive impairment



  • (1) Iversen L. Speed, Ecstasy, Ritalin: The Science of Amphetamines. 1 ed. London, UK: Oxford University Press; 2006.
  • (2) Theodorou S, Haber PS. The medical complications of heroin use. Current Opinion in Psychiatry 2005;18(3):257-63.
  • (3) Warner-Smith M, Darke S, Lynskey M, Hall W. Heroin overdose: causes and consequences. Addiction 2001 Aug;96(8):1113-25.