The non-intoxicating compound CBD is known to have a variety of beneficial effects, including reduction of pain and inflammation, and relief of anxiety. A single dose of CBD may keep working for several hours, and the cannabinoid may persist in the body for days or weeks. How long CBD effects last depends on several factors, including the user’s metabolism and if they use CBD regularly.
CBD (or cannabidiol) is stored in fat cells in your body, and theoretically can remain detectable for days or even weeks in a blood test. However, research on how long CBD oil stays in the system is spotty, because there’s no real demand for testing. Few employers care if employees consume a non-intoxicating drug that is used mainly to treat pain and anxiety—and commercial testing protocols don’t measure CBD anyway.
The first thing to know is that you need to absorb enough CBD for it to have any effect at all. Depending on how you administer CBD, much of its benefit can be lost. Swallowing it forces the drug to first pass through the liver, and as much as 95 percent never gets into the bloodstream. The highest bioavailability (how much is absorbed and gets into the bloodstream) comes from CBD that’s vaped or smoked, with CBD oil tinctures applied sublingually (under the tongue) finishing second.
Because inhaled CBD reaches the brain rapidly, users may feel a much more immediate and pronounced effect than they would from tinctures or edibles. But the therapeutic effects—reduced inflammation, pain and anxiety—are eventually noticeable from all forms of consumption, assuming you use enough. Proper CBD dosing can require some experimentation.
Generally, the effects of CBD wear off within just a few hours, but that depends on the amount of CBD taken, the method used, and the user’s size, metabolism, and history of use. If you begin to feel the pain or anxiety begin to return, you can simply take more CBD. There is no practical way to overdose on CBD.
CBD disappears from the body relatively quickly. In a study following 14 patients who were each given about 700 mg of CBD a day orally for six weeks, the average plasma level fell to just 1.5 ng/mL a week after the final dose, and was undetectable after that. The authors estimated the CBD half-life to be about 2-5 days.
It generally takes 5.5 half-lives for a drug to be fully eliminated from the system. So CBD taken orally would completely leave the body in about 11-28 days, but it may be impossible to detect on a blood test well before that. The half-life for vaped or smoked CBD in blood plasma is much shorter than for ingested CBD—just a few hours. A regular user may take longer to fully clear CBD from their system than an occasional or new user.
Research showing how long CBD is detectable in urine is rare, but one study showed a single test subject maintained detectable CBD in his urine for only 24 hours. In any case, CBD is almost never included in standard drug tests (like those given by employers).