Reviewed and updated: August 2026
Inhaled cannabis usually begins working within seconds or minutes and commonly produces noticeable effects for about two to four hours. Edible cannabis may take 30 minutes to two hours to begin, peak after two to four hours and last four to eight hours. Lingering effects or impairment can last 12 to 24 hours or longer.
How long does smoked or vaped cannabis last?
Inhalation delivers THC to the bloodstream quickly. Effects usually begin within seconds to minutes and are commonly felt for two to four hours. Dose, THC concentration, inhalation pattern, tolerance and individual metabolism can extend or shorten that window.
How long do edibles last?
When cannabis is eaten or drunk, it must pass through the digestive system and liver. Effects usually begin in 30 minutes to two hours, may be strongest after two to four hours and can last four to eight hours. Some people experience effects for longer.
Because onset is delayed, taking more before the first dose has fully taken effect is a common cause of cannabis poisoning.
Why can impairment last after the high fades?
Feeling less high is not the same as being unimpaired. Drowsiness and changes in attention, judgment, coordination or reaction time may persist. Health Canada warns that impairment can last for more than 24 hours after cannabis use in some circumstances.
What changes the duration?
- Product type and route of use
- THC and CBD content
- Dose and whether more was taken later
- Frequency of use and tolerance
- Food in the stomach
- Alcohol, medications or other drugs
- Age, health and individual metabolism
Can you drive after waiting six hours?
There is no universal waiting period that guarantees safe driving. Lower-risk guidelines have used at least six hours after cannabis, but impairment can last much longer. If there is any doubt, do not drive or operate equipment.
Frequently asked questions
Why do edibles last longer than smoking?
Edible THC is processed through the liver, producing 11-hydroxy-THC, while inhaled THC reaches the bloodstream through the lungs. The slower process creates later onset and often longer effects.
Does how long a high lasts equal how long cannabis is detectable?
No. Drug tests can detect cannabis metabolites long after noticeable effects and impairment have ended.
What should someone do after taking too much?
Stop consuming, move to a calm safe setting and avoid driving. Seek urgent help for severe symptoms. Call 911 for an emergency or a provincial poison centre for poisoning advice.
Primary sources: Health Canada, “Cannabis impairment”; Health Canada, consumer cannabis information; Health Canada, “Using a cannabis product.”
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