Illicit opioid information
What Is Heroin?
Heroin is an opioid made from morphine and is used non-medically. It can cause physical dependence and opioid use disorder, and overdose can be fatal, particularly when the illegal supply contains fentanyl or other potent opioids.
Overview
What is Heroin?
Heroin is an opioid made from morphine and is used non-medically. It can cause physical dependence and opioid use disorder, and overdose can be fatal, particularly when the illegal supply contains fentanyl or other potent opioids.
How it can affect the body
Heroin depresses the central nervous system. Effects may include euphoria, drowsiness, slowed breathing, nausea and reduced alertness. Potency and contamination in the illegal supply are unpredictable.
Dependence vs. addiction
Repeated opioid exposure can lead to tolerance and physical dependence. Opioid use disorder is diagnosed clinically based on the overall pattern of use and its consequences.
Signs of problematic use
- Difficulty reducing or controlling heroin use
- Withdrawal or strong cravings
- Using despite known harms
- Spending increasing time obtaining, using or recovering from opioids
Important health risks
- Fatal opioid overdose
- Fentanyl contamination in the illegal drug supply
- Respiratory depression
- Infections and other harms associated with injection
When emergency care is needed
If someone is unresponsive or breathing slowly after opioid use, call 911 immediately and give naloxone if available.
How addiction is medically assessed
A clinician can assess opioid-use patterns, withdrawal, health risks, prior treatment and goals before discussing treatment options.
Treatment options
Physician-led opioid agonist treatment may include Methadone, Suboxone or SROM/Kadian when clinically appropriate, together with ongoing monitoring and pharmacy support.
Treatment pathway
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Editorial transparency
Medical sources & review status
Prepared by the TSCP editorial team using Canadian public-health and clinical sources. A named medical reviewer is not displayed until TSCP confirms the reviewer and credentials.
Content updated: 2026-09-10