Does CBD Cancel THC? Examining How The Two Cannabinoids Interact

People who enjoy using marijuana recreationally are likely to have felt the effects of a common misstep: smoking or consuming “too much.”

Overindulging in weed can trigger undesired symptoms that include rapid heartbeat and nausea, anxiety and serious mood changes, difficulty focusing, confusion, and racing thoughts. Some users might even experience vomiting, hallucinations, panic attacks, delusions, paranoia, or psychosis.

Common wisdom says there’s not much you can do except try to remain calm, hydrate, and sleep off the troubling symptoms — although some experts have maintained for years that CBD might help “cancel” THC.

Research that received attention in the 2010s supported that theory, implying that taking some fast-acting CBD (in the form of CBD oil dropped under the tongue or a CBD vape) might counteract at least some of THC’s effects by preventing the psychoactive cannabinoid from binding to its targets in the brain.

A 2019 study with rats went even further, reporting that CBD appeared to “balance out” some of THC’s acute cerebral effects by disrupting excitement pathways in the brain and regulating the dopamine system that releases the “feel-good” hormone.

However, more recent research disputes those findings.

One small study at University College London found that regular cannabis users felt no difference in psychoactive effects between low-CBD marijuana and high-CBD weed. And another at Johns Hopkins Medicine reported that users experienced a more intense high when consuming edibles containing both THC and CBD than when using ones with only THC.

The Johns Hopkins researchers conclude that CBD, at high doses, interacts with THC to boost its effects in the body. That would intuitively make sense, since it’s been shown that the small amounts of other plant compounds in cannabis or CBD products — including all of their cannabinoids — work in an “entourage effect” to increase the active ingredient’s effectiveness.

In other words, earlier beliefs that CBD might ameliorate some of THC’s effects have now been called into question, so trying to reverse some of marijuana’s more troubling side effects by using CBD might not be the “magic bullet” that some have believed it to be.

Interesting in learning more? We have the details.

What Are CBD and THC?

Hemp and cannabis plants contain more than 100 plant compounds known as cannabinoids. The two most important are THC (tetrahydrocannabinol) and CBD (cannabidiol).

Both cannabinoids are believed to deliver significant medical benefits, but THC is the psychoactive compound that gets marijuana users high. CBD is non-intoxicating, so it delivers its apparent benefits without impairing users in any way.

Cannabis contains high levels of THC (and low CBD levels), so it’s easy to consume THC; smoking weed, or using marijuana edibles or concentrates, does the job. Hemp is rich in cannabidiol but contains very little THC, but users don’t generally smoke hemp because it doesn’t make them high (and smoking hemp flower is illegal in countries like the UK).

Instead, those who want to enjoy the apparent benefits of CBD generally use the CBD products that were legalised in most Western nations in the late 2010s. CBD oil, CBD capsules, CBD edibles, CBD vapes, and CBD topical products are all readily available in local shops and online in a variety of types and potencies.

How Do THC and CBD Deliver Their Effects?

We’ll be discussing two important similarities in this section.

The first is the similarity between THC and CBD, which have almost the same chemical structures. The only difference between them is the way their atoms are arranged.

That’s why THC and CBD behave in almost identical ways once they’re inside the body. They interact with a huge network of receptors and neurotransmitters known as the endocannabinoid system (ECS). The neurotransmitters act as messengers that shuttle between receptors and the body’s organs to deliver instructions that govern most of the body’s major functions.

The second similarity we’ll consider explains how THC and CBD are able to affect the ECS. Cannabinoids are almost identical to endocannabinoids, the umbrella term used to describe ECS messengers. And the similarity allows THC and CBD to interact with ECS receptors to send their own messages or change the ones that are already in the system.

The slight structural difference between THC and CBD means they head in different directions in the body, though. There are two sets of ECS receptors known as CB1 and CB2 receptors; they’re mostly found in different parts of the body and they control different key functions.

THC binds to the CB1 receptors, which are primarily located in the brain and nervous system. Those receptors govern thought and memory, pain, sleep, body temperature, appetite, and many other functions controlled by different parts of the brain. (Not incidentally, this is why THC intoxicates users, but CBD doesn’t.)

CBD mostly interacts with the CB2 receptors that govern crucial whole-body functions like inflammation and immunity and are largely found in other areas of the body. Cannabidiol does have minor interactions with CB1 receptors, just as THC has minor interactions with CB2 receptors, but the bulk of the cannabinoids’ activity is handled by their “favoured” receptors.

The Entourage Effect

When people use marijuana, they don’t just put THC into their bodies. The other plant compounds in cannabis — flavonoids, terpenes, and other cannabinoids including CBD — come along with the THC.

Similarly, when people use CBD products, they ingest small amounts of the other compounds found in hemp, including its small THC content.

Researchers have found the interaction between those compounds to be important, and they’ve named it the “entourage effect.” They’re still not sure exactly how it works, but the other compounds all work together with the active ingredient being consumed, either THC or CBD, to maximize the effects it delivers.

(CBD products are available with little or no THC content, as either broad-spectrum or CBD isolate products, respectively. They’re designed to help users who are allergic to THC or don’t want to flunk a cannabis drug test, but the elimination of THC reduces or eliminates the entourage effect and makes the products less effective.)

The existence of the entourage effect would seem to imply that CBD doesn’t “cancel” THC — it should theoretically make THC’s high even stronger. Until recently, however, research appeared to contradict that assumption.

CBD’s Interaction with THC

For several decades, most experts and researchers agreed that cannabidiol appeared to lessen some of THC’s psychoactive effects.

Results from just some of the studies:

• 2010 research published in the British Journal of Psychiatry reported that people using potent low-CBD cannabis and potent high-CBD cannabis each experienced the same type of “weed high,” but only those who had ingested low CBD marijuana experienced memory impairment. A similar study at Indiana University, published in the journal Cannabis and Cannabinoid Research a few years later, documented similar results.
• A study published in the Journal of Neuroscience showed evidence that CBD appeared to modulate the “neuropsychiatric side effects” of THC.
• And results of research published in the European Archives of Psychiatry and Clinical Neuroscience found that “low doses of CBD when combined with THC enhanced” the intoxicating effects of CBD, but high doses of CBD reduced them — appearing to confirm the effects of the entourage effect at low doses.

Some researchers concluded that CBD’s minor interaction with the ECS’s CB1 receptors served as an antagonist preventing all of THC’s effects, particularly ones that could potentially affect mental health, from reaching their highest possible levels.

Those involved in one 2019 animal study thought that there was even more involved than just ECS interaction. They believed that CBD disrupted neurological pathways that created excitement in the brain, while also slowing the production of the “feel-good” hormone dopamine stimulated by THC use.

More recently, though, several new studies have emerged showing that those optimistic conclusions might have been hasty.

One was conducted at University College London and published in the journal Addiction. Adolescent and adult cannabis users were given both low-CBD marijuana and high-CBD marijuana to vape. Their blood levels of THC were higher when they used the high CBD weed, possibly because of the entourage effect — but the effects they experienced were the same.

A similar study published by the American Medical Association was conducted at Johns Hopkins Medical. Users were given edibles, some with just THC and some with both THC and high doses of CBD. After consuming the THC/CBD edibles, once again, there was more THC in their blood — but they also reported experiencing an even more intense high than with just THC.

So, does CBD cancel THC?

The jury is still out. Further research is needed to determine why the studies have returned such different findings. Results showing that CBD may cancel THC in some cases, that it may enhance THC’s effects in some cases, or that it may have no effect at all, simply tell us only that the interaction between the two cannabinoids is not yet fully understood.