Last updated 9 August 2026 · Originally published 28 September 2022
Two different questions get muddled here, and it’s worth separating them before anything else.
How long you feel it is a matter of hours. How long it remains in your body can be a matter of days or longer. And if you’re asking because of a drug test, the real issue usually isn’t CBD at all — it’s any THC that came with it.
One caution before the detail: not feeling CBD doesn’t mean it has cleared. Don’t use sensation alone to decide when to take more — particularly with prescription CBD, where dosing should follow medical advice rather than how you feel.
How quickly it starts working
This depends almost entirely on how you take it, because the route decides how much CBD reaches your bloodstream and how fast.
Inhaled — fastest. CBD crosses from your lungs into your blood almost immediately, so effects arrive within minutes. It’s also the most efficient route: the one human study to measure it put inhaled bioavailability at roughly 31%, against an estimated 6% or so when swallowed on an empty stomach — a figure that has never been directly measured in people and rises several times over when CBD is taken with fatty food. Both numbers come from small studies and vary a good deal with product, dose and study design.[1]
Under the tongue — potentially faster than swallowing, but less predictable than the marketing suggests. Some CBD is absorbed through the lining of the mouth, which avoids the liver on the way in. But ordinary oil is often swallowed before much of that happens. In one small study, drops and capsules produced very similar blood levels, and both peaked at around four hours.[3]
Swallowed — capsules, gummies, drinks, anything you eat. Slowest, because it has to go through your digestive system and then your liver, which breaks most of it down before it reaches circulation. Any noticeable effect may take an hour or two to emerge, sometimes longer — and blood levels can keep rising for several hours after that.
On your skin — ordinary creams and balms are meant to act locally, and little tends to reach the bloodstream. Transdermal patches and purpose-built formulations are a different matter: they’re designed to carry cannabinoids through the skin and into circulation.
One thing worth knowing about swallowing: taking CBD with food, particularly fatty food, significantly increases how much gets absorbed.[1] The same capsule can behave quite differently on an empty stomach.
How long the effects last
This is the vaguest part of the picture, and the least well studied.
Inhaled CBD tends to come on fast and fade sooner; swallowed CBD takes longer to arrive and its effects tend to be more drawn out. But that’s a general pattern rather than a reliable rule — route, dose and formulation all interact.
Where people do notice something, consumer guides commonly put it at several hours, often around two to six. That isn’t an established universal duration, and plenty of people don’t feel a distinct onset or offset at all. CBD frequently produces no obvious acute effect, which is precisely what makes “how long does it last” so hard to answer.
How long it stays in your system
Much longer than you feel it, and this is where people get caught out.
CBD’s half-life — the time for the amount in your blood to halve — varies a lot by route. A systematic review of human studies found roughly 1.4 to 11 hours after an oromucosal spray, about 31 hours after smoking, and two to five days with repeated daily oral use.[2]
That last figure is the important one. CBD is widely distributed through the body and highly fat-soluble, so with repeated dosing it can accumulate — and how quickly people metabolise and eliminate it varies considerably. Someone taking it daily has a very different profile from someone who tried a gummy last Tuesday.
It’s also worth understanding what a half-life actually means, because it’s routinely misread. A half-life of two to five days doesn’t mean CBD is gone in two to five days — it means half of it is. Clearing most of a drug generally takes around five half-lives.
So there’s no dependable point at which you can call CBD “gone.” After a single low dose, blood levels fall substantially over the following days. With repeated high-dose use, CBD and its metabolites may persist considerably longer. And the answer depends on what’s being tested for, how sensitive the test is, and whether “gone” means absent or simply below the detection threshold.
The drug test problem
Worth being blunt about this, because it’s the reason most people ask.
Standard workplace drug tests don’t look for CBD. They look for THC and its metabolites — so the question isn’t how long CBD lasts, it’s whether your product contains THC.
Full-spectrum products contain THC by design. The amount may be small, but repeated use — and sometimes even a single product containing more THC than its label suggests — can produce a positive result. Broad-spectrum and isolate products shouldn’t, though “THC-free” labelling isn’t always accurate.
If you’re subject to testing, our guide to full spectrum, broad spectrum and isolate covers what to look for. No unregulated retail product can guarantee you’ll pass.
Why the numbers are so vague
Because the research is thinner than you’d expect for something this widely used.
The systematic review that produced the half-life figures above sifted 792 papers and found only 24 with usable human pharmacokinetic data — and its authors were explicit about the gaps and inconsistencies.[2] Nobody has properly established the absolute bioavailability of CBD by most routes.
So treat any confident-sounding number, including the ones here, as a rough guide rather than a schedule.
For more, see our guide to CBD and what the research actually shows, or browse Using CBD.
References
- Lucas CJ, Galettis P, Schneider J. The pharmacokinetics and the pharmacodynamics of cannabinoids. British Journal of Clinical Pharmacology. 2018;84(11):2477–2482. doi:10.1111/bcp.13710
- Millar SA, Stone NL, Yates AS, O’Sullivan SE. A systematic review on the pharmacokinetics of cannabidiol in humans. Frontiers in Pharmacology. 2018;9:1365. doi:10.3389/fphar.2018.01365
- Johnson DA, Funnell MP, Heaney LM, et al. Cannabidiol oil ingested as sublingual drops or within gelatin capsules shows similar pharmacokinetic profiles in healthy males. Cannabis and Cannabinoid Research. 2024;9(5):e1423–e1432. doi:10.1089/can.2023.0117
About this article
Substantially rewritten in August 2026. This update separates how long CBD’s effects last from how long it remains in the body, replaces the earlier figures with data from a systematic review of human pharmacokinetic studies, and explains why drug tests look for THC rather than CBD.
