There isn’t one fixed answer to how long a cannabis high lasts. The timing depends on how cannabis is used, how much THC is taken, and how each person responds. The noticeable feeling may fade before every effect on attention, reaction time, or coordination has passed.
If cannabis is smoked or vaped
Effects can begin within seconds or minutes. Health Canada says it may take 10 to 30 minutes to feel the full effects. Its consumer information chart gives a typical duration of about 2 to 4 hours for inhaled cannabis, while other Health Canada guidance warns that effects may last up to 6 hours. Some effects, including drowsiness or impairment, may linger for 12 to 24 hours.
If cannabis is eaten or taken by mouth
Edibles, drinks, oils, and capsules can take longer to be felt. Effects may begin after 30 minutes to 2 hours, and it can take up to 4 hours to feel the full effect. Health Canada’s consumer chart gives a typical duration of 4 to 8 hours; its lower-risk guidance says effects may last up to 12 hours, with some residual effects lasting as long as 24 hours.
That delay is one reason people can take more before the first dose has fully taken effect. Taking additional cannabis too soon can lead to stronger or more unpleasant effects than intended.
Why the timing varies
Duration can change with the amount and strength of THC, the way it is used, a person’s experience and frequency of use, health and body factors, and whether cannabis is combined with food, alcohol, medications, or other substances. The same person may respond differently from one occasion to another.
Feeling less high doesn’t always mean the effects are gone
Cannabis can affect attention, memory, judgment, and reaction time. Those effects may remain after the most noticeable part of the high has faded. Health Canada says there is no standard waiting time to drive after using cannabis: don’t drive, cycle, or operate machinery while you may be impaired.
A few ways to reduce the chance of an unpleasant experience
- Follow the directions provided by your health care practitioner for medical use.
- Read the product label and keep track of how much THC you use.
- With edibles, allow time for the full effects to develop before considering more; Health Canada says this can take up to 4 hours.
- Avoid combining cannabis with alcohol or other drugs, which can increase impairment and the risk of adverse effects.
- Talk with a health care professional or pharmacist about cannabis and prescription or over-the-counter medications.
If someone has severe confusion, extreme anxiety, paranoia, or hallucinations after using cannabis, Health Canada advises calling the Poison Centre at 1-844-POISON-X (1-800-463-5060 in Quebec), calling 9-1-1, or going to the nearest hospital.
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Sources and further reading
- Health Canada: Consumer information on cannabis
- Health Canada: What you need to know if you choose to consume cannabis
- Health Canada: Cannabis impairment
- Seedsman: “How Long Does a Cannabis High Last?” (topic inspiration)
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