You may recall from chemistry class the term “half-life”—the time it takes for an element to decay by half its original value. While often utilized in nuclear physics to describe the decay of radioactive atoms, the concept also applies to the metabolization of substances by biological processes in the human body. Alcohol, prescription medications, metals, and even water have biological half-lives and deteriorate at different rates.
In this blog post, we’ll address the following:
CBD is no different. It decays like all other compounds, but that rate of decay varies depending on many factors. A 2014 study titled Cannabidiol: Promise and Pitfalls concluded that the half-life of orally-administered CBD was about 1 to 2 days. In other words, if you were to take 40 mg of CBD, only 20 mg would remain after 1 to 2 days. As noted in a 2012 study, CBD half-life changes based on the method of consumption:
A general rule of thumb in pharmacokinetics, which studies how drugs move throughout the body, is that it takes 4 – 5 half-lives for a drug to be effectively eliminated. The point at which the intake of a drug is at equilibrium with its elimination is known as its “steady state.” In keeping with the previous example, if the half-life of CBD is assumed to be 1 to 2 days, then it would take anywhere between 4 to 10 days for any given dosage of CBD to reach this steady state.
It’s important to note that these are merely ballpark estimates and that multiple other factors contribute to varying rates of CBD decay, including:
Because of this, it can be very difficult to assess exactly how long CBD lingers in the body, and at what concentrations. CBD is fat-soluble and can build up and store in fat cells for quite a while, especially in daily and high-BMI users. Those who live very active lifestyles, on the other hand, will most likely metabolize CBD at a faster rate than even a moderately active person. Likewise, all other things being equal, a younger person will naturally metabolize CBD faster than someone much older.
Arguably, the most crucial factor when it comes to drug elimination is the frequency of use. How much and how often someone uses a substance will have a major and perhaps the most significant effect on how long it takes for that substance—be it CBD or any other drug—to dissipate completely.
Unfortunately, there is no single definitive answer to the question of how long CBD stays in your system; there are just too many different contributing factors. But it’s also essential to address the reasoning behind such an inquiry. Too often, it’s a question pitched by CBD enthusiasts who are worried about testing positive for THC in a drug test as a result of their CBD use, although this is exceptionally rare (as discussed in a separate blog post).
As the market for CBD continues to expand, so will the need for additional clinical trials and another scientific testing. In due time, we may yet gain more detailed insight into the effects—and duration—of CBD in the body.