Pot has the overriding perception as the chill-out drug. In fact, almost a third of marijuana users in the U.S. say the main purpose of it is to reduce anxiety or stress, a recent Marist poll found.
But that’s not always the case—in fact, lighting up leaves lots of people paranoid, anxious, and eager for the high to fade. And that can impact those who are not prone to anxiety.
Turns out, there are several factors that can turn a blissfully mellow high into heart-racing paranoia. Here’s what’s going on.
How Pot Gets You High
The high you experience with marijuana actually mimics a process your body has in place to keep anxiety levels in check, says Gregory Gerdeman, Ph.D., an assistant professor of biology at Eckerd College.
This happens through what’s called your endocannabinoid system: One of its functions is to cool down brain synapses that release stimulating neurotransmitters, the primary “go” signal used in brain circuits, says Gerdeman. The endocannabinoid system helps pump the brakes by triggering the release of cannabinoids, chemical compounds that bind to cannabinoid receptors throughout your brain and body. That sends the signal to chill out when we’re wired.
“These receptors are expressed at high levels in areas of the brain that have to do with mood regulation,” says Steven Kinsey, Ph.D., an associate professor of psychology and coordinator of the Behavioral Neuroscience Training Program at West Virginia University. In 2014, a study from Vanderbilt University found that many of these cannabinoid receptors are found in the amygdala, a part of the brain that regulates anxiety and the fight-or-flight response.
Marijuana contains plant-based cannabinoids, too. So when you smoke, vape, or otherwise consume weed, the cannabinoids bind to the same receptors in your body. And that triggers the same relaxing feeling as the release and binding of your body’s own cannabinoids does.
But the truth is, this system doesn’t always go according to plan. There are some factors that can make your hit more likely you to tweak you out than bliss you out.
Higher Levels Of THC Can Make You More Anxious
THC, short for tetrahydrocannabinol, is the psychoactive compound of cannabis, which binds directly to the cannabinoid receptors, says Kinsey. At lower doses this tends to be pretty relaxing. However, the higher the dosage, the more likely it is to spark an anxious reaction.
It’s called a biphasic response, says Gerdeman. As you start to take in small amounts of THC, it can cause a therapeutic effect. But the higher you go, the more likely you are to trigger the opposite effect.
Controlled research here is limited and individual tolerance varies, says Gerdeman, but a recent study provides a benchmark. Researchers from the University of Chicago tested how THC amounts influenced 42 pot users under stressful conditions. Those who took in 7.5 milligrams (mg) of THC felt less stressed by a mock interview than participants given a placebo, and their stress levels went down faster, too.
But those who took in 12.5 mg of THC reported negative emotions during the mock interview, and were more likely to rate the task as “challenging” or “threatening.”
For reference, Gerdeman says that a joint with about one gram of cannabis flower that has a 15 percent THC content would contain about 150 mg of THC. (Of course, the THC content could be much higher and the joint could be fatter than a single gram, so this isn’t a guarantee.) Some of that THC gets destroyed in the burn, and how much you inhale and your lungs absorb varies widely based on your smoking technique. So if you were to say, smoke a whole joint (not advisable), you’d probably go way beyond that 12.5 mg of THC and straight into the stress zone.
Researchers aren’t exactly clear why more pot leads to the opposite response of lower doses. But like with any drug, it might have to do with differing thresholds, explains Kinsey.
“Some people have a very broad tolerance to the drug, and this is true of sugar and tobacco and alcohol,” he says. “And there can become a point where it’s no longer fun. For example, I enjoy gummy bears. But there are only so many I can eat before I feel sick.”
Tolerance likely depends on a number of factors, including genetics, the makeup of your own neural network in your brain, and how much you’ve used the drug, Kinsey says.
But Another Pot Compound Can Counteract THC
THC is just one piece of the puzzle, though—there are more than 60 other cannabinoids that have been identified in marijuana, including cannabidiol, or CBD. And it seems like CBD actually lessens the stress-promoting consequences of too much THC.
It’s possible that CBD may tone down the receptors that THC binds to by blocking endocannabinoid metabolism, so the effect of the THC may not be as intense—and therefore less likely to steer you into anxiety, says Gerdeman. It’s also possible that CBD also acts on the receptor for serotonin in your brain, which can turn down your stress response.
Overall, lighting up a joint with more THC and less CBD is far more likely to stress you out, says Kinsey.
So if you don’t want to get paranoid, just pick a strain that has more CBD, right?
Well, it’s not so easy. While different strains of cannabis have different levels of THC and CBD, you don’t really know how much of each cannabinoid you’re getting—no matter what your dispensary says.
For example, strains like ACDC, Cannatonic, and Harlequin are touted for their low THC and high CBD content, and pretty much everything else, like OG Kush, is said to be high in THC. But experts say that this is largely, well, BS.
“Just somebody saying, ‘this Blue Dream,’ or ‘this is a heavy sativa,’ or ‘this is a heavy indica’ is practically meaningless these days,” says Gerdeman. “There’s so much misinformation that sometimes breeders don’t even know.”
Researchers have proven this point by purchasing different samples of the same strain in the same city and using advanced testing methods to see what’s really in there, says Dr. Kinsey. Oftentimes, they’re completely different from each other (and different from what the person selling it claims).
Edibles Are Particularly Tricky
Your high depends mainly on the levels of THC and CBD—not necessarily the method you use to consume it, says Kinsey.
However, edibles in particular are much more likely to have high levels of THC in them, which makes them more likely to cause paranoia. Many of them also have very little CBD and other cannabinoids, so you’re losing out on some of the offsetting compounds as well. Plus, ingesting your drugs, rather than smoking, delays the high. Impatient users often consume too many edibles, which can lead to a bad trip.
A reasonable dose of a single-serving edible should generally have about 10 mg of THC, says Gerdeman, which falls in between the calming 7.5 mg and the stress-inducing 12.5 mg pinpointed in the University of Chicago study (so your reaction really will depend on your personal tolerance). But many products that dispensaries sell are much higher, and thus more likely to cause anxiety.
“For most people, if they eat 30 mg of THC in an edible dose, there are going to be a lot of psychoactive side effects that they don’t want,” says Gerdeman. In addition to anxiety and paranoia, Gerdeman says this can also cause sedation, delirium, and dizziness upon standing. Not fun. (Here’s what happened when one man ate too many edibles.)
Even though individual tolerance levels differ, any product with between 30 to 40 mg of THC without much CBD present is pretty likely to stress you out—though the most tolerant and accustomed users may be exempt, says Gerdeman.
Again, though, a package stating a dosage may not be that reliable. Many edibles are mislabeled, says Gerdeman, and there’s pretty much no regulation—plus, if a batch hasn’t been very thoroughly mixed, you may end up with a part that has way more (or less) THC than a label says.
Your Age and Your Mood Can Affect Your High, Too
Your brain changes as you age, and so does your endocannabinoid system, says Gerdeman. For instance, receptor density gets lower as you get age.
“If somebody smoked robustly in their 20s and picked it back up in their 30s, their brain’s endocannabinoid system may not be at the same set point,” says Gerdeman. That’s why you may notice getting paranoid when you smoke now, whereas pot may have mellowed you out when you were in college.
It’s not just you, though—there’s another way time affects your high. Over the past several decades, marijuana has been bred to have way higher levels of THC than it did in the good old days, says Kinsey.
According to Gerdeman, experts say that the percentage of THC in cannabis was about 7 percent in the 70s, while it’s often about 20 percent these days and often much higher. (Remember, as a middle ground, 15 percent THC content in one gram of cannabis flower would shake out to about 150 mg.) However, Gerdeman stresses that these estimates aren’t necessarily that accurate because the old data may not be reliable as what’s out there now.
Even so, if you think you’re smoking the same amount that you used to—say, you always cut yourself off after one joint shared between a handful of buddies—the THC may be off the charts compared to what you used to buy.
What’s more, how you’re feeling can affect your tolerance too. When life is stressing you out, you might be more susceptible to the anxiety-inducing effects of pot. There’s a bit of emotional release that happens when you get high, and if you’re barely controlling your emotions without weed, adding a joint or edible into the mix could give your subconscious mind permission to, well, freak out, says Gerdeman. This isn’t true for everyone, of course—some people find it useful to let go a little bit when they’re dealing with a particularly tough or vulnerable time.
Setting is also important, too, Gerdeman adds: If you’re already super paranoid about where you are or having your wife walk in when you’re smoking up, for example, you may be more likely to feel more paranoid when you’re actually high.
If anxiety hits during your next high, the best thing you can take a time out. Go for a breather, but don’t drive anywhere.
“Your liver will help clear it out, but the more THC you have on board the longer that will take,” Kinsey says. How long are we talking? Depending on how much you consumed and your own body chemistry, it could take a couple hours (or more), says Gerdeman—but it will pass, he assures.
Still, if pot continues to make you feel crappy, that might be a sign to put down the joint. Plus, while the climate around recreational pot use is changing, and it’s now legal in several states, no one knows how it affects your health down the line.