Dr. Danial Schecter said marijuana can have unwanted effects on the cardiovascular system. One of the most common side effects of cannabis, a spike in heart rate, happens to be one of the scariest and can even turn new users off from the plant. Get the essential information related to CBD and heart arrhythmia. Modern studies and anecdotal reports are included.
Expert cautions people with heart problems about using cannabis
Cannabis can have troublesome effects on people with unstable heart conditions, says physician
Dr. Danial Schecter said marijuana can have unwanted effects on the cardiovascular system. (Submitted)
A medical cannabis expert is cautioning people with heart problems about using marijuana.
Dr. Danial Schecter is one of the keynote speakers at a cardiology symposium today in Sydney, N.S.
Schecter is the co-founder of the Cannabinoid Medical Clinic, which has 20 Canabo Medical Clinic locations across Canada, including one in Halifax.
He said although cannabis is generally safe, it does have side-effects, which have been largely overlooked as Canada moves to legalize its recreational use.
“Cannabis activists have almost taken over the conversation around cannabis, and their message is that cannabis is a harmless drug, it’s never killed anyone in the 5,000 years people have been using it.”
Schecter, who also holds a fellowship in hospital medicine and is an active hospitalist at the Royal Victoria Regional Health Centre in Barrie, Ont., suggests cannabis can have troublesome effects on people with unstable heart conditions.
“It can cause what we call tachycardia, which is an increase in your heart rate. It can also cause peripheral vasodilation, which means your veins and your arteries can dilate and drop your blood pressure,” said Schecter.
“And that means that people who are using cannabis with unstable heart diseases, such as unstable angina or at high risk of having a heart attack or stroke, should really use cannabis with caution.”
Schecter said people with unstable heart diseases or who are at high risk of having a heart attack or stroke should be careful about using cannabis. (Evan Mitsui/CBCNews)
Schecter said like all drugs, cannabis also can produce unwanted side-effects when combined with other medications or alcohol. His presentation is intended to flag potential risks for cardiologists and other medical professionals attending the Sydney event.
Schecter noted that it’s the THC, or tetrahydrocannabinol, in cannabis that produces both the high associated with marijuana and the negative side-effects.
“So if people consume CBD [cannabidiol]-only products, or oils, then they don’t get the same cardiovascular effects, or the other unwanted side-effects.”
Why cannabis can make your heart race
For a healthy individual cannabis-induced tachycardia is usually harmless, and knowing more about what cannabis is doing to your body can make you feel better about the unpleasant feeling. (Shutterstock)
One of the most common unwanted side effects of cannabis, a spike in heart rate, also happens to be one of the most troublesome and can even turn new users off from the plant.
“If you don’t explain that it’s possible that you can have a little acceleration of the heart for maybe 5 or 10 minutes and that it’s nothing to worry about,” said Janosch Kratz, MD, on The Cannabis Enigma podcast, “he gets nervous and says, ‘oh God, why did I take this drug.’”
For a healthy individual cannabis-induced tachycardia is usually harmless, and knowing more about what cannabis is doing to your body can make you feel better about the unpleasant feeling.
So why can cannabis raise your heart rate? Is it dangerous? And what can you do about it? Let’s find out.
How cannabis affects your heart in general
Cannabis has a number of common side effects, ranging from mild ones such as red eyes, dry mouth, or the munchies, to potentially more unpleasant effects such as anxiety, paranoia, and short-term memory difficulties.
These side effects, and how cannabis affects the cardiovascular system, are related to how it modulates what is known as the endocannabinoid system. The endocannabinoid system affects a wide range of bodily functions including hunger, pain, sleep, and energy, to name a few.
The major active chemicals in cannabis — cannabinoids — are able to trigger receptors that control the endocannabinoid system, modifying the function of those receptors and the connected systems, including the cardiovascular system.
“The interactions of the endocannabinoid system with the autonomic nervous system seem to be the driving force behind the reported cardiovascular adverse events [from cannabis],” wrote a group of researchers who recently reviewed years of cannabis studies 1 .
Why cannabis makes your heart race
The main culprit is widely-considered to be tetrahydrocannabinol (THC), the cannabinoid also responsible for the high of marijuana. (Shutterstock
An increased or irregular heart rate, also known as tachycardia, can be a side effect of cannabis use. In fact, smoking cannabis can lead to a 20-100% increase in heart rate for a couple hours or more after consumption 2 . This is believed to be due to a widening of the blood vessels, which is also responsible for those red eyes people get after using cannabis.
In higher doses cannabis can also lead to a drop in blood pressure, resulting in dizziness and lightheadedness.
The main culprit for these effects of cannabis is widely-considered to be tetrahydrocannabinol (THC), the cannabinoid also responsible for the high of marijuana.
One of the more oft-cited, albeit dated reports states that inhaling cannabis smoke and ingesting THC reliably increases the heart rate by 20-50% over baseline. A lab study carried out on rodents in 1985 further showed that THC significantly alters the levels of catecholamine — hormones that are produced by the adrenal glands and are responsible for the body’s “fight or flight” response — in the bloodstream.
Research has also shown that as one’s tolerance to cannabis increases, the severity of side effects often decreases 3 . This means that side effects commonly seen with inhaled cannabis, including increased heart rate and reduced blood pressure, is not as common in regular users.
It should be noted that almost all studies on the risks of cannabis use are based on people who inhaled marijuana smoke, and that with more and more people now preferring other methods and types of cannabis, these risk assessments should be updated. In other words, like with some other cannabis side effects, the effect on heart rate can be partly attributed to the act of smoking itself 4 .
Could lower THC strains affect your heart rate less?
Since THC is often cited as being responsible for the increased heart rate after cannabis use, one might logically conclude that choosing lower-THC strains — or lower doses in general — would help mitigate it. It would also follow that eating edibles high in THC could produce the same side effects.
Dr. Deepak Cyril D’Souza, a professor of psychiatry at the Yale University of Medicine told NBC news in November, 2020 that he has spent 25 years studying the effects of marijuana and THC and that “in our studies on THC, we found a very robust increase in heart rate and an effect on blood pressure that can be quite profound.”
A 1988 trial found that women given very low-THC (1.8%) joints showed “statically significant increases in pulse rate,” and this increase was more pronounced and lasted longer for participants with a past history of intermittent marijuana use 5 . The trial did not include a control population given a lower dose of THC however.
The most well-known and common strains (more correctly referred to as “chemovars”), high in THC and low in cannabidiol (CBD) and often bred for a strong high and medicinal benefits, are increasingly referred to as Type I cannabis. Type II chemovars have more of a balance between CBD and THC, while Type III chemovars are CBD dominant with little-to-no THC.
All types of cannabis can be used therapeutically, but types II and III tend to allow for better control of THC doses and are often preferred by healthcare professionals due to the reduced risk of side effects. Type III cannabis, despite containing small amounts of THC, is generally considered non-intoxicating.
It is increasingly accepted that CBD, which doesn’t cause an intoxicating effect, can counteract some of the effects of THC. (Shutterstock)
What about CBD?
It is increasingly accepted that CBD, which doesn’t cause an intoxicating effect, can counteract some of the effects of THC 6 . This happens because CBD can actually modify THC binding with certain receptors of the endocannabinoid system.
In other words, using a strain that has less THC or more of a CBD-dominant profile, should — by virtue of containing less THC — produce a less powerful high, and may reduce the anxiety that can commonly accompany a THC high.
As far as the effects CBD itself has on the heart, a 2017 trial found that a single dose of CBD reduced resting blood pressure and helped mitigate stress-induced blood pressure and heart-rate increases 7 .
A 2013 comprehensive published in Frontiers in Psychology looked at CBD’s ability to offset the “adverse psychological effects of THC,” and concluded that “the few studies that exist on the effects of CBD show that this cannabinoid can counteract some of the negative effects of THC.”
Is sativa or indica worse for your heart rate?
It’s conventional wisdom in cannabis that sativa strains are upbeat and indica strains are mellow and likely to induce the “couch lock” sensation. Countless cannabis consumers use these characterizations to shape their consumption or purchasing decisions
Unfortunately, there isn’t much scientific evidence to support this notion of indica vs sativa as a method of distinguishing between the effects of different types of cannabis. While there are many factors at play in determining why a cannabis chemovar produces certain effects, calling them indica or sativa is not one.
What does matter is the cannabinoid profile of the chemovar (how much THC, CBD, and other cannabinoids) and its terpene makeup. The various terpenes in cannabis not only determine its flavor and aroma, but may also have a big impact on its effects, including how energetic or sedative the high is.
Also, it’s worth keeping in mind that this can be very individualistic. The right dose for one individual can be very different than the right dose for another person, and a strain that makes one person very upbeat and giggly could induce a couch-lock sensation for someone else. And while a specific strain may be very relaxing to one person, another user could experience anxiety or paranoia, but this would not indicate that this is a universally-experienced effect of the cannabis variety in question. The same could be true for increased heart rate.
Is cannabis dangerous for the heart?
If you are a young, healthy person with no history of cardiac illness, then you probably should not be overly concerned about the cardiovascular side effects of cannabis use.
A 2018 review of existing research into marijuana use and cardiovascular risk factors found that there is “insufficient” evidence about how marijuana affects cardiovascular risk factors including stroke and heart attack 8 . The researchers stated that the current literature on the matter is limited by “recall bias, inadequate exposure assessment, minimal marijuana exposure, and a predominance of low-risk cohorts.”
That doesn’t mean that there may not be cause for concern. In fact, there is a substantial amount of data to suggest cannabis may increase the risk of cardiac disease
Researchers in 2014 examined the reporting of cardiovascular complications related to cannabis use and found that they “indicate cannabis as a possible risk factor for cardiovascular disease in young adults.” 9 More recently, a 2017 review discussed “harmful effects of cannabis use including fatal cardiovascular events that could be related to cannabis use,” including but not limited to increased heart rate and blood pressure and a heightened risk of acute coronary events 10 .
Cardiac-related mortality data from the U.S. National Vital Statistics System for 1990-2014 and showed a statistically significant increase of 2.4% in the rate of cardiac death among men following the passage of medical cannabis programs, as well as 1.3% increase among women 11 .
Other research has found that cannabis use is associated with an increased risk of cardiac dysrhythmia 12 , as well as non-fatal stroke, transient ischemic attack 13 , and acute myocardial infarction 14 . Importantly, cannabis users are more likely to be using tobacco products than non-cannabis users, which may contribute to these negative cardiac outcomes.
In general, if you are considering using cannabis, you may want to speak to your physician about the possible side effects, especially if you have a history of cardiovascular issues.
Can you do anything about increased heart rate from cannabis?
When it comes to cardiovascular health and cannabis, many of the same healthy lifestyle principles apply: Try to limit or cut out smoking as an intake method, exercise regularly, eat healthy, and try to get a full night’s sleep as often as possible.
If you find that you often get anxiety or your mind (along with your heart) races when you get high, then consider trying a lower-THC variety, or one that has more of an even balance between THC and CBD. This will help keep your THC dose lower and reduce the likelihood of a racing heart and racing mind.
And when those intense feelings strike, use some tried and true ways to bring your high down a little bit. First off, don’t panic. Remember that the high will wear off before too long, and this isn’t a permanent condition. Try to focus on your breathing, taking deep breaths to help you relax and bring your anxiety down. You can also try to find something funny on the TV, put on an album you love listening to, and when in doubt, raid the cupboard for snacks.
CBD and Heart Arrhythmia: What We Know So Far
The relationship between CBD and arrhythmia is somewhat complicated.
Contemporary scientific research shows that CBD has a potentially beneficial effect on arrhythmia, and on the cardiovascular system as a whole.
On the other hand, a small percentage of people experience an increased heart rate and heart palpitations when they use CBD, which are known symptoms of arrhythmia.
Before we get into more details of the research, let’s briefly explain arrhythmia.
Cardiac arrhythmia is a group of conditions characterized by an irregular heartbeat, where the heart either beats too rapidly or too slowly.
One of the main symptoms of arrhythmia are heart palpitations, which are characterized by increased awareness of the contraction of the heart, often accompanied by the hard and irregular beating of the heart.
Unlike CBD, which is non-psychoactive, THC (the most abundant psychoactive cannabinoid in the cannabis plant) is known to cause rapid heartbeat and heart palpitations.
This especially happens to novice users, but also if the user consumes too much THC at once.
Smoking Too Much Cannabis? Here’s How to Overcome It
This occurs because THC significantly lowers blood pressure, which causes the heart to pick up the pace and beat faster.
For a very large percentage of users, CBD doesn’t produce this effect but some people do experience irregular heartbeats and heart palpitations from consuming cannabidiol.
A good example of how rarely this happens is this 2019 study, which analyzed the effects of CBD on people suffering from chronic pain.
This research had 97 patients (30 to 65 years old), and only one of them experienced an increased heartbeat from using CBD.
Patients were using two soft gels per day for 8 weeks, and each soft gel contained 15.7mg of CBD, and 0.5mg of THC.
The woman who experienced a rapid heartbeat reported that the treatment “made her heart race”.
The reasons behind this occurrence are still unknown, but if it happens to you, it’s important to understand the difference between CBD products.
Full-spectrum CBD products have a significant amount of THC, and other minor cannabinoids and terpenes are also present in these products.
If you’re especially sensitive to THC, these types of products can definitely induce a rapid heartbeat and palpitations.
Compared to full-spectrum products, broad-spectrum CBD products have a lesser amount of THC in them, and they also contain minor cannabinoids and terpenes.
Broad-spectrum products are far less likely to induce palpitations, although it’s still possible.
Finally, CBD isolates are the third type of CBD products. They only contain CBD, and nothing else. These products are least likely to cause a racing heart or palpitations.
Full Spectrum CBD vs CBD Isolate: Which Should You Choose?
It’s important to mention that CBD isolates are considered the least beneficial type of CBD products because cannabinoids work synergically in the body.
This synergistic cooperation of different cannabinoids is known as the entourage effect, because the presence of THC and other cannabinoids increases the health benefits of CBD.
Even though some users experience arrhythmia-like symptoms from CBD, an animal study from 2010 found that an acute administration of CBD suppressed ischaemia-induced arrhythmia.
Ischaemia is a restriction of blood to tissues, which causes a shortage of oxygen that is necessary for keeping tissues alive.
The researchers also stated that CBD reduced the size of infarction (tissue death), when it was given at reperfusion injury.
A 2013 review mentioned that current evidence suggests CBD has positive effects on the cardiovascular system, but that clinical research on human participants is required to determine if these positive effects will translate to the human cardiovascular system.
Finally, a 2018 review stated that cannabinoids appear as promising therapeutic agents for cardiovascular diseases.
Since the research on the effects of CBD on arrhythmia (and the cardiovascular system in general) is still in its starting phases, it probably isn’t wise to consume it for these purposes until more is known on the subject.
On the other hand, if you’re experiencing heart palpitations from CBD products, make sure to follow our guidelines regarding different types of CBD products.
If these heart-related symptoms persist, you can also consider lowering the dose or perhaps even discontinuing your CBD regimen.