Cannabis affects you for anywhere from a few hours to a full day, depending on how you consume it, how much you take, and how often you use it. The psychoactive high from smoking or vaping typically peaks within 10 minutes and fades over two to four hours, while edibles can keep you feeling high for six to eight hours. But the effects that matter, like impaired coordination and foggy thinking, can linger well beyond the point where you stop feeling stoned.
Smoking and Vaping: The Fastest Timeline
When you inhale cannabis, THC crosses from your lungs into your bloodstream almost immediately. Blood levels peak within 6 to 10 minutes, and that’s when the high feels strongest. The intense part usually lasts 30 minutes to an hour, then gradually tapers. Most people feel essentially sober within two to three hours after a moderate dose, though higher doses stretch that window.
The rapid onset also means the effects are somewhat easier to predict and control. You feel what you’re getting in near real-time, which is why smoking and vaping tend to produce shorter, more manageable experiences compared to edibles.
Edibles: A Much Longer Ride
Edibles follow a completely different path through your body. After you swallow a gummy or brownie, your digestive system breaks it down, sends THC to the liver, and only then does it reach your brain. That process takes 30 to 60 minutes, sometimes longer on a full stomach. Peak blood levels don’t arrive until about three hours after you eat the dose, which is why many people make the mistake of taking more before the first dose has fully hit.
Once it does kick in, an edible high generally lasts six to eight hours. The liver converts THC into a metabolite that crosses into the brain more efficiently and produces a more intense, longer-lasting experience than inhaled THC. This is also why edibles are more likely to produce uncomfortable effects if you overshoot your dose. A 5 mg edible and a 20 mg edible aren’t just different in intensity; the higher dose will keep you impaired for significantly longer. Research using oral doses ranging from 5 to 20 mg found dose-dependent impairment lasting over three hours even at moderate levels, with higher doses extending that window further.
How Long You’re Actually Impaired
Here’s where the timeline gets tricky: the period you feel high and the period you’re actually impaired don’t line up perfectly. A randomized clinical trial published in JAMA Psychiatry tested driving performance after smoking cannabis and found that driving ability was significantly worse at 30 minutes and 90 minutes post-use. At 3.5 hours, performance was still borderline impaired. It didn’t fully return to normal until about 4.5 hours.
The more concerning finding was that nearly 69% of participants said they felt ready to drive at the 90-minute mark, even though their actual driving performance hadn’t improved from right after smoking. In other words, people consistently underestimate how long cannabis impairs their coordination and reaction time. The subjective feeling of being “fine” returns well before your motor skills actually do.
For edibles, this gap is even wider. Since the high lasts six to eight hours and the impairment window extends beyond the subjective peak, you can realistically be too impaired to drive safely for most of a day after a moderate edible dose.
Next-Day Effects
Some people report feeling foggy or “off” the morning after using cannabis, and there’s limited evidence to back that up. A systematic review of next-day studies found that most cognitive tests conducted 12 to 24 hours after THC use showed no significant impairment. Out of 345 tests across published studies, only 12 indicated lingering negative effects.
The impairments that did show up in the 8-to-12-hour window involved perception, divided attention, working memory, and time estimation. Two older studies using flight simulators found measurable impairment at the 24-hour mark, though those involved doses around 20 mg, which is higher than what most casual users consume. For most people using moderate amounts, cognitive function returns to baseline by the next morning. But if you used a high-dose edible late in the evening, some residual sluggishness the following day is plausible.
Why Duration Varies So Much Between People
Several factors explain why your friend might feel sober after two hours while you’re still feeling it at four. The biggest ones are dose, body composition, and genetics.
THC is highly fat-soluble, meaning your body quickly stores it in fat tissue. From those fat deposits, THC slowly releases back into the bloodstream. In occasional users, the half-life of THC in blood plasma is one to three days. In chronic users, it stretches to 5 to 13 days. This doesn’t mean you’re high for days, but it does mean trace amounts are circulating in your body long after the psychoactive effects wear off.
Genetics play a surprisingly large role. About 70% of THC clearance depends on a single liver enzyme. Some people carry a genetic variant that reduces this enzyme’s activity to roughly 7% of normal levels. For those individuals, oral THC exposure is about three times higher than in people with the standard version of the gene. That means the same edible produces a stronger, longer-lasting effect purely because of how slowly their body breaks it down. You wouldn’t necessarily know which version you carry, which partly explains why some people have unexpectedly intense or prolonged reactions.
How Tolerance Changes the Timeline
If you use cannabis regularly, the duration and intensity of each session generally decrease over time. Research consistently shows that frequent users experience less prominent subjective, cognitive, and physiological effects compared to occasional users. Cognitive function shows the highest degree of tolerance, with some studies finding a complete absence of acute impairment in heavy daily users performing tasks that clearly affected infrequent users.
The intoxicating and heart-rate effects also blunt with regular use, though to a lesser extent. This means a daily user might feel their high fade in an hour or less from the same dose that keeps an occasional user impaired for three to four hours. Tolerance doesn’t make cannabis harmless or eliminate impairment entirely, but it substantially compresses the timeline of noticeable effects.
Detection vs. Actual Effects
THC remains detectable in your body far longer than it affects your mind. Blood tests can pick up THC for one to two days after a single use and potentially weeks after heavy, prolonged use because of the slow release from fat stores. Urine tests detect THC metabolites for roughly 3 to 30 days depending on use frequency. Hair tests can go back 90 days.
None of these detection windows reflect how long you’re impaired. A positive drug test days or weeks after use doesn’t mean you were still feeling effects. The psychoactive window, even in a worst-case scenario with a high-dose edible in someone who metabolizes THC slowly, tops out at roughly 12 hours. The gap between “detectable in your system” and “actively affecting your brain” is enormous, and it’s worth understanding that distinction if you’re facing a drug test or wondering whether residual THC in your body is doing anything.