What is the legal THC limit for driving in Canada?

Under the Criminal Code, having 2 to under 5 ng of THC per mL of blood within two hours of driving is an offence with a maximum $1,000 fine, and 5 ng/mL or more is a more serious offence. Being impaired to any degree is also an offence, and many provinces have zero-tolerance rules.

Can I use medical cannabis at work?

Medical cannabis is treated like other prescription medication, and employers have a duty to accommodate up to undue hardship. That does not allow anyone to work while impaired, and smoking or vaping cannabis is prohibited in many workplaces.

Cannabis, driving and work: the basics

Last reviewed October 25, 2026 · Based on official government sources

Driving while impaired by cannabis is a criminal offence across Canada, and many provinces add stricter rules of their own. Workplaces have rules too. This guide explains the basics from official sources. It cannot tell you when it is safe to drive, because, as Ontario notes, there is no way to know exactly how long to wait after using cannabis. If you have used cannabis, do not drive.

Federal impaired driving law

The Criminal Code makes it an offence to drive while your ability is impaired to any degree by alcohol, a drug, or both. It also sets limits on THC in the blood, measured within two hours of driving. According to the Department of Justice:

2 to under 5 ng of THC per mL of blood: a less serious offence, with a maximum fine of $1,000.
5 ng/mL or more: a more serious offence with higher penalties.
Alcohol and THC combined (a blood alcohol concentration of 50 mg per 100 mL plus 2.5 ng/mL of THC or more): a more serious offence.

Police can use approved oral fluid (saliva) screening devices at the roadside, standardized field sobriety tests and drug recognition evaluations, and can demand a blood sample.

Provincial rules are often stricter

Quebec: zero tolerance for every driver. It is prohibited to drive or have care or control of a road vehicle with any detectable cannabis or other drug in your saliva.
Ontario: zero tolerance for drivers 21 and under, novice drivers (G1, G2, M1, M2) and certain commercial drivers. Penalties can include immediate licence suspension, fines and vehicle impoundment.
British Columbia: zero tolerance for new drivers in the Graduated Licensing Program (immediate 12-hour suspension), and immediate 90-day driving prohibitions for drivers over the limits.
Newfoundland and Labrador: zero tolerance for novice drivers, drivers under 22 and commercial drivers.
Saskatchewan: a zero-tolerance approach to drugs and driving.
Manitoba: provincial sanctions including licence suspension, vehicle impoundment and ignition interlock, on top of criminal penalties.

Having a medical authorization does not make it legal to drive impaired.

Carrying cannabis in a vehicle

Using cannabis in a vehicle is prohibited in most provinces, including for passengers. How cannabis must be carried also varies. Ontario requires it to be in its original, unopened package or packed in baggage and not readily available. B.C. and Newfoundland and Labrador require it to be sealed in its original package or out of reach of everyone in the vehicle. Nova Scotia requires a closed, sealed package out of reach. The simplest approach is to keep it sealed and in the trunk.

At work

Employment and Social Development Canada says the Cannabis Act amended the Non-smokers’ Health Act to prohibit smoking and vaping cannabis in federally regulated workplaces. Provinces have similar rules; Ontario, for example, prohibits smoking or vaping cannabis in enclosed workplaces.

Workers have a duty to work safely, and employers have a duty to manage hazards, which can include impairment. The Canadian Centre for Occupational Health and Safety recommends that employers have a clear impairment policy that covers all substances, not only cannabis. Some key points from official sources:

Medical cannabis should be treated like any other prescription medication. An employee with the right authorizations can trigger the employer’s duty to accommodate, to the point of undue hardship. Accommodation does not mean a person may work while impaired.
Drug testing rules come from decisions of courts, arbitrators and human rights bodies. Testing is generally limited to safety-sensitive positions in specific situations.
In Quebec, an employer may regulate or prohibit cannabis use as part of its management rights.
In Yukon, it is illegal to be at work while impaired by cannabis or any other substance.

Ask your employer for its impairment policy. If you have a question about your own situation, speak with your employer, union, or provincial occupational health and safety office.

Frequently asked questions

What is the legal THC limit for driving in Canada?: Under the Criminal Code, having 2 to under 5 ng of THC per mL of blood within two hours of driving is an offence with a maximum $1,000 fine, and 5 ng/mL or more is a more serious offence. Being impaired to any degree is also an offence, and many provinces have zero-tolerance rules.
Can I use medical cannabis at work?: Medical cannabis is treated like other prescription medication, and employers have a duty to accommodate up to undue hardship. That does not allow anyone to work while impaired, and smoking or vaping cannabis is prohibited in many workplaces.

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Sources

Facts in this guide were taken from these official sources, checked October 25, 2026.

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