CBD basics
How long does CBD stay in your system?
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It depends on how often it is taken. A systematic review found single oral doses cleared with half-lives of about 1 to 2 hours in blood, while chronic oral dosing produced half-lives of 2 to 5 days. A Phase I trial of daily dosing reported a terminal half-life near 60 hours, so regular users carry CBD for days after stopping.
"How long" has two different answers, because CBD behaves one way after a single serving and another way after weeks of daily use. The molecule is fat-soluble, so it moves into fat tissue and leaks back out slowly. The more of it stored, the longer the tail.
What is the half-life of a single dose?
A half-life is the time for blood concentration to fall by half. A 2018 systematic review in Frontiers in Pharmacology pooled 24 human studies and found the half-life depends heavily on route and duration. For single oral doses of 10 and 20 mg, the reported half-lives were 1.09 and 1.97 hours. Oromucosal spray ran 1.4 to 10.9 hours. After intravenous dosing it was about 24 hours and after smoking about 31 hours.
Those short oral numbers describe the first, fast phase of clearance from blood. They do not mean CBD is gone in a few hours; they mean the blood level drops fast while tissue stores hold on.
Why does daily use change the number?
Because the stores fill up. The same review reports a half-life of 2 to 5 days after chronic oral dosing. A Phase I trial in CNS Drugs gave healthy adults 750 or 1500 mg of purified CBD twice daily for a week and measured a terminal half-life of about 60 hours, with effective half-lives of 10 to 17 hours. Steady state arrived after about 2 days, and blood levels accumulated 1.8- to 2.6-fold compared with the first dose.
Put together: a person taking CBD every day for a few weeks will take several days, and possibly a week or more, to clear it after stopping. A person who took one serving once will clear most of it within a day. Dose size, body fat, food with the dose and the formulation all move the number.
Does "in your system" mean it will show on a test?
Not for CBD itself. Federal workplace panels under the HHS Mandatory Guidelines test for THC metabolites at a 50 ng/mL screen and 15 ng/mL confirmation; CBD is not an analyte. The relevant question for testing is how long the THC in a full-spectrum product stays, and THC metabolites behave like CBD in one respect: they accumulate in fat with repeated use and clear slowly. Isolate and broad-spectrum products with ND THC on the certificate of analysis sidestep that issue.
Is it different for pets?
Yes, and in both directions. The Merck Veterinary Manual reports elimination half-lives of 0.5 to 5.8 hours in dogs and 6.7 to 13.2 hours in cats, with oral bioavailability of 6 to 20 percent. Dogs clear CBD faster than people do, which is why canine studies dose every 12 hours. Cats hold it longer, which is one reason feline dosing is handled more cautiously.
The honest summary, in the words of the Frontiers review authors, is that "robust data from a variety of formulations is required." The ranges above are the best published numbers, not a promise about any one person.
This page is general information, not personalized guidance.
General information, not personalized guidance.
Sources
- A Systematic Review on the Pharmacokinetics of Cannabidiol in Humans Frontiers in Pharmacology, via PubMed Central (accessed 2026-10-13)
- A Phase I, Randomized, Double-Blind, Placebo-Controlled, Single Ascending Dose, Multiple Dose, and Food Effect Trial of the Safety, Tolerability and Pharmacokinetics of Highly Purified Cannabidiol in Healthy Subjects CNS Drugs, via PubMed (accessed 2026-10-13)
- Mandatory Guidelines for Federal Workplace Drug Testing Programs (82 FR 7920) Federal Register, via GovInfo (accessed 2026-10-13)
- Toxicosis in Dogs and Cats From Cannabidiol (CBD) Merck Veterinary Manual (accessed 2026-10-13)
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