Health Canada has amended regulations allowing doctors to prescribe heroin to people who are severely addicted to opioids.
The government says the country is facing an opioid overdose crisis and healthcare providers need help in treating patients suffering from chronic dependency.
The change to the former Conservative government's legislation means pharmaceutical-grade heroin can be prescribed under a special-access program in cases where traditional treatment has failed.
However, Health Canada says that while there is scientific evidence to support emergency access to the drug, the treatment is not an option for most people.
Health Minister Jane Philpott has said the government will hold a summit this fall to address the issue of opioid addiction that has led to hundreds of overdose deaths across Canada.
Supervised heroin therapy is used in several countries, including Switzerland, Germany and the Netherlands, and a clinical trial in Canada has concluded injectable heroin was more effective than standard methadone treatment.