How long a high lasts depends almost entirely on what substance you’re talking about and how it enters your body. A cannabis high from smoking typically lasts up to 6 hours, while an edible can stretch to 12. An alcohol buzz peaks within 60 to 90 minutes and fades over several hours. Psychedelics like mushrooms and LSD can keep you altered for 6 to 10 hours. Below is a practical breakdown of the most commonly searched substances, what affects the timeline, and why the same drug can hit two people very differently.
Cannabis: Smoking vs. Edibles
The method of consumption changes everything with cannabis. When you smoke or vape, THC hits your bloodstream through your lungs and you feel effects within seconds to a few minutes. The high peaks around 30 minutes in, then gradually tapers. Total effects last up to 6 hours, though some residual grogginess or mental fog can linger up to 24 hours.
Edibles are a completely different experience. Because THC has to pass through your digestive system and liver before reaching your brain, onset takes anywhere from 30 minutes to 2 hours. This delay is why people often make the mistake of eating more before the first dose kicks in. The high peaks around 4 hours after eating and can last up to 12 hours total, with residual effects stretching to 24 hours. A 10 mg edible and a few puffs of a joint might contain similar amounts of THC, but the edible produces a longer, often more intense experience because your liver converts THC into a more potent form before it reaches your brain.
Alcohol
Alcohol takes 60 to 90 minutes to reach peak levels in your blood after you start drinking. The subjective buzz, that warm, loosened-up feeling, generally tracks with your blood alcohol level as it rises and falls. Your body clears alcohol at a fairly fixed rate, and the half-life is about four to five hours. That means it takes roughly 25 hours for your body to fully eliminate all alcohol from a heavy drinking session, even if you stopped feeling drunk much earlier.
The “high” itself, meaning the period where you feel noticeably intoxicated, depends heavily on how much you drank. A couple of beers might produce a mild buzz lasting an hour or two. A night of heavy drinking can leave you impaired for 6 hours or more, followed by a hangover that’s essentially your body still processing the aftermath.
Psychedelics: Mushrooms and LSD
Psilocybin mushrooms produce a trip that usually wraps up within about 6 hours. Effects typically begin 20 to 40 minutes after eating them, build to a peak over the next couple of hours, then gradually wind down. Most people feel essentially back to normal by hour 6, though some mental and emotional aftereffects can persist into the next day.
LSD lasts significantly longer. A single dose can keep you in an altered state for a full 10 hours, sometimes longer. This is one of the key practical differences between the two: if a mushroom trip goes badly, you’re closer to the exit. An uncomfortable LSD experience has a much longer runway. Both substances can leave you feeling emotionally drained or unusually reflective for a day or two afterward, even after the primary effects wear off.
Caffeine
Caffeine’s effects can last anywhere from 2 to 12 hours, but for most people, half the caffeine clears your system in 4 to 6 hours. That means a coffee at 3 p.m. could still have half its caffeine circulating at 9 p.m. The alertness and energy boost you feel typically peaks within an hour, then gradually fades. Sleep experts generally recommend cutting off caffeine at least 8 hours before bedtime, because even when you no longer feel “wired,” enough caffeine may remain in your system to reduce sleep quality.
Prescription Stimulants
Prescription amphetamines like Adderall come in two forms that produce very different timelines. The immediate-release version kicks in within 30 to 45 minutes and lasts about 4 to 6 hours. The extended-release version starts working just as quickly but uses a two-stage bead system: half the medication dissolves right away, while the other half releases about 4 hours later in your intestines. This gives extended-release versions a total duration of 8 to 12 hours from a single dose.
Why the Same Substance Hits People Differently
Your body’s ability to break down substances is controlled largely by a family of liver enzymes. These enzymes vary significantly from person to person based on genetics, age, liver health, and what other substances are in your system. In older adults, the liver’s processing capacity drops by 30% or more because the liver shrinks and receives less blood flow. This means the same dose can produce a longer, stronger high in a 65-year-old compared to a 25-year-old. Newborns and infants have underdeveloped versions of these same enzyme systems, which is why medications must be carefully dosed for children.
Chronic liver disease, heart failure, and certain medications can all slow down how quickly your body clears a substance, effectively extending the high. Other drugs can speed up or slow down the same liver enzymes, which is why mixing substances produces unpredictable results. Two people taking the same edible at the same party can have wildly different experiences based on their body composition, enzyme activity, and what they ate that day.
How Tolerance Changes the Timeline
If you use a substance repeatedly, your body adapts in two ways. First, your liver enzymes become more active and break the substance down faster, so less of it reaches your brain. Second, the receptors in your brain that the substance targets become less responsive, either decreasing in number or weakening their bond with the drug. The result is that regular users often experience a shorter, weaker high from the same dose.
This is why someone who smokes cannabis daily might feel a high for only an hour or two from the same amount that keeps an occasional user elevated for four or five hours. The metabolic clearance rate hasn’t changed dramatically, but the window where the substance produces noticeable subjective effects shrinks. The classic response to tolerance is taking more, which resets the intensity but also accelerates the cycle. With substances like alcohol and opioids, this pattern carries serious risk because the dose needed to feel high creeps closer to the dose that causes dangerous physical effects.