Dr. Danial Schecter said marijuana can have unwanted effects on the cardiovascular system. Does CBD Affect Heart Rate? We Review the Science and Conduct Our Own Experiments to Find Out It’s well known that THC increases heart rate and blood pressure, and that this is likely related to
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.”
Does CBD Affect Heart Rate? We Review the Science and Conduct Our Own Experiments to Find Out
It’s well known that THC increases heart rate and blood pressure, and that this is likely related to THC’s anxiety and psychosis-inducing effect. But what about CBD, THC’s cannabinoid cousin? CBD has an opposite effect on anxiety, psychosis, and brain function as THC: it reduces anxiety, strengthens brain connections, and reduces symptoms of psychosis.
Could it reduce heart rate as well?
There are several studies that explore CBD’s effect on heart rate, and we go over them thoroughly in this article. But we decided that wasn’t enough, and we put the science to the test on our favorite guinea pigs (us).
I tested CBD’s effect on my resting heart rate, my heart rate after cardio, and my heart rate after a (particularly extreme) sauna session. Keep reading to find out the results.
Does CBD affect heart rate?
Yes, CBD may reduce heart rate under stressful conditions, but the evidence is mixed on whether CBD has any effect on heart rate in non-stressful conditions.
What the science says
Here’s a review of all the major studies conducted on CBD and heart rate:
- In one 2009 study published in the British Journal of Pharmacology , rats were subjected to stressful conditions that increased their blood pressure and heart rate. After being given a dose of CBD, their heart rate and blood pressure decreased.
- In this 2017 randomized, double-blind, placed controlled clinical trial published in the Journal of Clinical Investigation ,CBD was found to reduce blood pressure in healthy male participants but increase heart rate compared to the placebo group.
- In a 2011 study published in the Journal of Neuropsychopharmacology , participants were given either a large dose of CBD prior to a public speaking event or a placebo. The researchers reported lower blood pressure, heart rate, and anxiety levels for the CBD group.
So, the two studies which applied CBD in stressful conditions (one in rats and one in humans) both found reduced blood pressure and heart rate, but the study which applied CBD in non-stressful situations found only a reduction in blood pressure and an increase in heart rate.
Does CBD only affect heart rate in stressful conditions?
This suggests that CBD may only reduce heart rate if heart rate has otherwise been increased by stressful conditions. This makes sense because increased heart rate and blood pressure is a result of autonomic arousal, aka the “fight or flight” response that is activated upon stress. Autonomic arousal is also the mechanism behind anxiety and panic attacks, and CBD is well-known as an effective anxiety reliever: one 2019 study in The Permanente Journa l and another in the Journal of Neurotherapeutics both found that CBD reduced anxiety.
So, CBD anxiolytic (anti-anxiety) effects are likely related to its potential ability to reduce heart rate.
CBD and THC: two very different cannabinoids
It’s important to note that, while CBD and THC are both derivatives of cannabis, when it comes to acute cardiovascular function they appear to have opposite effects: THC increases autonomic arousal, whereas CBD reduces it; CBD may reduce heart rate, but THC is known to increase heart rate.
This key difference in the two cannabinoids — in how they affect the nervous system — explains why one, THC, is associated with increased anxiety and psychosis, while the other, CBD, is associated with the opposite.
The difference also provides further reason to believe that CBD and THC may function best in combination, especially given the substantial evidence indicating that CBD may reduce negative side-effects of THC (including on brain function). For instance, in this September 2019 study just conducted by the University of Western Ontario , they found that CBD blocked the psychiatric side-effects of THC. PhD candidate and head researcher Roger Hudson explained that “ CBD was also able to reverse the anxiety-like behaviour and addictive-like behaviour caused by the THC.”
What about CBD’s overall effect on the cardiovascular system?
As with CBD’s effect on heart rate, this is a very open question. Bottom line is: we don’t know, because little research has been done on CBD’s effect on the cardiovascular system.
Large studies on marijuana use and cardiovascular function have found little definitive evidence of a positive or negative effect, and since CBD has much less of an impact on the cardiovascular system than THC it’s reasonable to assume that CBD has minimal impact on cardiovascular health overall.
But there’s more to it than that, and two recent studies have indicated that CBD may in fact have a positive effect on cardiovascular health.
Two studies: CBD reduces heart inflammation
In this 2013 review of several studies published in the British Journal of Clinical Pharmacology , CBD was found to positively influence white blood cell survival and migration related to heart disease. The researchers concluded that “ A common theme throughout these studies is the anti-inflammatory and antioxidant effect of CBD. In the heart, in vivo CBD treatment protects against ischaemia-reperfusion damage and against cardiomyopathy associated with diabetes.”
The second 2016 study published in the Journal of Molecular Medicine CBD reduced markers of inflammation in individuals with autoimmune myocarditis, a condition which causes inflammation of the heart.
So, while it’s far too early to determine how exactly CBD influences cardiovascular function, there is promising evidence that CBD’s known anti-inflammatory properties apply to the heart as well, and that CBD can potentially reduce heart-related inflammation.
The CBD heart rate experiment
So, there’s the hard science on how CBD affects heart rate. Now, for the fun part: I put it to the test. To measure my heart rate I used a FitBit, and for each test I took 40 mg of NuLeaf Naturals organic full-spectrum CBD oil.
Given that the science indicates different results in different conditions, we tested CBD’s effect on my heart rate in three different conditions: resting, during exercise, and after a sauna session.
Test 1: Resting heart rate
This is the simplest test we conducted: each day over a period of three days, at the same time (2:00 PM) each day, we measured my heart rate without CBD, and then I took a 40mg dose of NuLeaf Naturals organic full-spectrum CBD oil, we waited 30 minutes, and we measured my heart rate again. We then took the average of all three measurements. Here are the results:
|Day 1||Day 2||Day 3||Average|
As you can see, I did experience a modest reduction in heart rate after taking the CBD, though the reduction wasn’t consistent and it wasn’t outside the normal variation in my heart rate.
Test 2: Heart rate while exercising
For this test, I ran for 20 minutes on a treadmill at a constant rate (5mph), got off the treadmill and measured my heart rate, then took a dose of CBD, waited 30 minutes, got back on the treadmill at the same rate for the same time (20 mins) and measured my heart rate again. As with the first test, we did this three times over three days and took the average of all three.
|Day 1||Day 2||Day 3||Average|
Again, we found a relatively small reduction in heart rate, though this reduction was consistent across all three days.
Test 3: Heart rate after sauna
This test was a bit more complicated. I’m a regular sauna user, and fewer things jack your heart rate up more than the sauna. I was curious if CBD would have any effect on how quickly my heart rate returned to normal after a sauna session.
Here’s the test: I did a 20 minute sauna session at 200 degrees (brutal) without CBD then measured my heart rate immediately after getting out, and then again every three minutes to determine how long it returned to normal. The next day I repeated the same process but with CBD.
|Immediately after sauna||3 minutes after sauna||6 minutes after||9 minutes after||12 minutes after|
The results for this one are interesting: my heart rate was higher immediately after getting out with CBD, but fell faster with the CBD and reached a lower point 9 minutes after.
None of the results of my experiments were SUPER eye-catching, but as you can see from the charts I did experience a modest but noticeable reduction in heart rate after taking CBD across all three experiments. However, these tests also were all under non-stressful conditions: even the ones involving cardio and sauna ultimately aren’t a great test of the “fight or flight” response. The increased heart rate and blood pressure during physical activity is a physical adaptation that’s different from the increase you’d see with anxiety.
A better test, and one that I will try to conjure up over the next few weeks, is testing my heart rate under anxiety-inducing conditions, and then testing with CBD under the same conditions to see if there’s any difference. Stay tuned, folks!
FAQ on CBD and Heart Rate
Does CBD affect heart rate medication?
Actually, CBD is metabolized by the same liver enzymes as 60% of medications on the market, so it can block these enzymes and allow more of the medication into your system. If you are on any medications, including heart rate medication, discuss CBD with your doctor before using.
Does CBD increase your heart rate?
One study we reviewed did record an increase in heart rate after consumption of CBD (though the blood pressure of the participants was lowered). However, other studies (and our own experiments) indicate that CBD is more likely to decrease heart rate.
Does vaping CBD increase heart rate?
Vaping CBD does allow you to consume more concentrated doses of CBD, which may have more of an affect on heart rate than other methods. But the evidence indicates that even at more potent doses CBD is more likely to decrease than increase your heart rate.