<p>Canada’s toxic drug crisis continues to worsen in the country’s urban centres, with the unregulated drug supply becoming more deadly and causing life-altering harms. The increasingly toxic mix of substances in the unregulated supply is the primary driver of drug poisoning deaths. We anticipate that the current toxicity of the supply will persist, and may worsen, until people are able to access alternatives to the poisoned supply. As the leaders responsible for public health in the country’s largest urban centres, we understand that harm reduction and addiction treatment services are complementary medically necessary health services that enable people who use substances to survive and work toward their health and wellness goals. Harm reduction and treatment, along with prevention, are pillars of a serious response to the drug toxicity crisis. Neither should be prioritized to the exclusion of the other. In this commentary, we highlight the critical harm reduction measures that are being implemented to save lives and reduce the risks of substance use, and we point to some of the ways that these programs could be expanded to improve the health and well-being of people who use drugs and the capacity of the public health system to respond to the crisis.</p>