Why THC gets you high and CBD doesn't

THC, CBD, cannabinoids, psychoactive effects — you've likely heard at least a couple of these terms if you've been trying to understand THC, CBD, and the differences between them. Maybe you've also encountered the endocannabinoid system, cannabinoid receptors, and even terpenes. But what's it all really about?

If you're looking for a way to understand why THC products get you high and CBD products don't and what they have to do with endocannabinoids, welcome, you're in the right place.

Cannabinoids and the role of the ECS

To understand THC vs CBD and how they affect us, you first need to understand the endocannabinoid system (ECS), which helps the body maintain functional balance through its three main components: “messenger” molecules, or endocannabinoids, that our bodies produce; the receptors these molecules bind to; and the enzymes that break them down. 

Pain, stress, appetite, energy metabolism, cardiovascular function, reward and motivation, reproduction, and sleep are just a few of the body's functions that cannabinoids impact by acting on the ECS. The potential health benefits of cannabinoids are numerous and include inflammation reduction and nausea control.

What THC does

The most abundant and well-known cannabinoid found in the cannabis plant is tetrahydrocannabinol (THC). It activates the CB1 receptor, an ECS component in the brain that governs intoxication. THC intoxication has been shown to increase blood flow to the prefrontal cortex, the region of the brain responsible for decision-making, attention, motor skills, and other executive functions. The exact nature of THC's effects on these functions varies from person to person.

When THC binds to CB1 receptors, it also triggers feelings of euphoria from the brain's reward system. Cannabis activates the brain's reward pathway, which makes us feel good, and increases our likelihood of partaking again in the future. THC's effect on the brain's reward system is a major factor in cannabis' ability to produce feelings of intoxication and euphoria.

What CBD does

THC is far from the only ingredient in cannabis that has a direct impact on brain function. The most notable comparison is with cannabidiol (CBD), which is the second most abundant cannabinoid found in the cannabis plant. CBD is often touted as non-psychoactive but this is misleading since any substance that has a direct effect on the function of the brain is psychoactive. CBD most certainly creates psychoactive effects when it interacts with the brain and central nervous system, as it reportedly has very powerful anti-seizure and anti-anxiety properties. 

So while CBD is indeed psychoactive, it's not intoxicating. That is, it doesn't get you high. That's because CBD is exceedingly bad at activating the CB1 receptor. In fact, evidence suggests that it actually interferes with the activity of the CB1 receptor, especially in the presence of THC. When THC and CBD work together to affect CB1 receptor activity, users tend to feel a more mellow, nuanced high and have a much lower chance of experiencing paranoia compared to the effects felt when CBD is absent. That's because THC activates the CB1 receptor, while CBD inhibits it

How CBD and THC interact with each other

Put simply, CBD may protect against cognitive impairment associated with overexposure to THC. A 2013 study published in the Journal of Psychopharmacology administered THC to participants and found that those who had been given CBD prior to THC administration showed less episodic memory impairment than patients who had been given a placebo — further indicating that CBD may curb THC-induced cognitive deficits.

In fact, a 2013 review of nearly 1,300 studies published in scientific journals found that “CBD can counteract the negative effects of THC.” The review also points out the need for more research and a look at CBD's effects on THC consumption in real-world scenarios. But the existing data is clear enough that CBD is often recommended as an antidote for those who have inadvertently consumed too much THC and find themselves overwhelmed. 

Cannabinoids interact with many systems in the body

THC and CBD bind to several other targets in the body. CBD, for example, has at least 12 sites of action in the brain. And where CBD may balance the effects of THC through inhibiting CB1 receptors, it may have other effects on THC metabolism at different sites of action.

As a result, CBD may not always inhibit or balance THC's effects. It may also directly enhance THC's potential positive medical benefits. CBD may, for example, enhance THC-induced pain relief. THC is potentially both an anti-inflammatory and neuroprotective antioxidant, largely due to its activation of CB1 receptors in the pain-control area of the brain. 

A study from 2012 revealed that CBD interacts with alpha-3 (α3) glycine receptors, a crucial target for pain processing in the spine, to suppress chronic pain and inflammation. It's an example of what's called the entourage effect, in which different cannabis compounds work together as a whole to produce a greater effect than if consumed separately. 

But even this interaction is not entirely clear. In a February 2019 study, researchers found that low doses of CBD actually enhanced the intoxicating effects of THC, while high doses of CBD reduced the intoxicating effects of THC.

Terpenes and the entourage effect

It's entirely possible that some of cannabis' most well-known side effects (such as couch-lock) may have very little to do with THC itself, but rather, the relative contributions of lesser-known molecules. Chemical compounds called terpenes give cannabis plants their unique tastes and aromas. They are found in many plants — like lavender, tree bark, and hops — and provide the scent of essential oils. Terpenes, which are the largest group of known phytochemicals in cannabis, have also proven to be a critical part of the entourage effect. Not only do terpenes give cannabis a distinct flavor and aroma, but they also appear to support other cannabis molecules in producing physiological and cerebral effects.

Bottom line

Cannabis is a complex plant with relatively little available research into its effects on and interactions with the human body — and we're just beginning to learn the many ways THC, CBD, and other cannabis compounds work together and interact with our ECS to change the way we feel.

Major contributions from Dr. Adie Rae.

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The information contained in this site is provided for informational purposes only, and should not be construed as medical or legal advice. This page was last updated on June 20, 2022.