Research suggests that marijuana can impact blood pressure in humans. Some studies even indicate that cannabis use could be a helpful way to lower blood pressure and treat conditions like hypertension. Still, other research shows conflicting results — that it could be a risk factor for increased blood pressure. While we don’t yet have enough evidence, scientists continue to study whether and how it could be effective.
How cannabis impacts blood pressure
Cannabis works primarily by modulating a system in the human body known as the endocannabinoid system. This system includes chemicals naturally produced by the human body called endocannabinoids, cannabinoid receptors, which are activated by endocannabinoids, and enzymes which clear the endocannabinoids from the body. This system is believed to be responsible for maintaining homeostasis or balance in a wide range of bodily functions, including mood, sleep, energy, hunger, and pain response.
The chemicals in cannabis, called cannabinoids, are also able to trigger these cannabinoid receptors, and thus modulate many of the functions that the endocannabinoid system is involved in regulating.
Studies have revealed that the endocannabinoid system plays a key role in cardiovascular activity. In animal studies looking at these cardiac factors, researchers have noted that activation of this system can cause significant changes in heart rate, blood vessel constriction, inflammation, oxidation, and blood pressure — both increasing and decreasing blood pressure in different contexts.
In cardiovascular disease states we generally see an upregulation of the endocannabinoid system, so researchers believe that the body’s endocannabinoids play a role in the progression of cardiovascular disease.
In particular, there are studies that show an association between an overactive endocannabinoid system and maladies like arterial, pulmonary and portal hypertension.
Still, researchers aren’t sure whether these elevated endocannabinoid levels are causing these problems with heart health, or if they are being deployed by the body as a counteractive measure to balance out the problems.
When tested in animal studies, endocannabinoids have shown both the potential to widen blood vessels, thereby lowering blood pressure, and to contract blood vessels, thus raising blood pressure.
The evidence cannabis lowers blood pressure
Given what we know about how the endocannabinoid system and how it impacts blood pressure, it’s likely that the cannabinoids present in cannabis will also have some effects. Because of this, there is great interest in the therapeutic potential of cannabis for modulating blood pressure.
Anecdotally, many medical cannabis users report that cannabis has increased their cardiovascular health and well-being. Unfortunately, the actual research on this is somewhat limited and conflicted.
Some studies suggest that cannabis use can lower blood pressure and reduce risk of hypertension. For example, animal studies on rodents with high blood pressure found that activating the endocannabinoid system by adding cannabinoids reduced blood pressure, while blocking cannabinoid receptors increased blood pressure.
In one review of the literature, researchers reported that cannabis doesn’t have an immediate impact, but can lead to longer term lowering of blood pressure. In these studies, while they found increased heart rate with use, they didn’t see immediate changes in blood pressure. Still, this review found that chronic cannabis use was tied to lower blood pressure and heart rate overall.
In another study, researchers found that cannabis withdrawal could lead to spikes in blood pressure. Researchers observed and monitored heavy cannabis users before and after a period of cannabis abstinence. While the cannabis users had normal blood pressure before going cold turkey, abruptly stopping caused some participants’ blood pressure to spike — actually hitting hypertensive ranges.
Since this only impacted 31% of the participants, researchers on this study hypothesised that cannabis might be offering protection from high blood pressure and, when that protection was removed, these patients stopped benefiting from cannabis’ blood pressure lowering effects. For those with heart problems who are already using cannabis, the authors of this study suggest that stopping should only be done under doctor supervision to ensure that blood pressure levels stay in a safe range.
While we might assume that these studies reflect impacts from THC, the primary cannabinoid in cannabis, it’s also important to note that cannabis contains many different compounds. It’s possible some of the research is conflicted because different types of cannabis may have different effects.
For example, research looking at the cannabinoid CBD, while limited, suggests that it can both lower blood pressure directly and reduce stress that can cause increases in blood pressure. Some researchers even suggest CBD may be helpful for treating hypertension. Another study found that blocking endocannabinoid receptor activity reduced blood pressure for obese patients with hypertension. Still this research is in early phases and more needs to be investigated before we can make any firm conclusions.
The evidence cannabis raises blood pressure
The studies above indicate that cannabis may be a helpful treatment for those suffering from high blood pressure. Still, other research suggests the opposite, with findings suggesting that cannabis can actually increase blood pressure. For example, one study on six individuals found that recent cannabis use temporarily increased blood pressure within an hour of taking the medicine.
A review of the literature on cannabis and heart health didn’t find any links between cannabis use and hypertension, but it did find some evidence that suggested cannabis use leads to an increased risk of ischemic stroke — another condition associated with high blood pressure.
Survey based studies have added to this confusing state of affairs. One study looked at the correlation between blood pressure and cannabis and reported that those who had ever used cannabis (even just once) were more than three times more likely to die from high blood pressure. Still, this survey was limited because it did not look at dosing, frequency of use, or chemical profile, and it is unclear whether those surveyed may have used other illicit drugs, and if so, whether those were a factor.
In a later survey study, researchers found no relationship between ongoing cannabis use and high blood pressure. They did find that recent cannabis use led to increased systolic blood pressure, but chronic cannabis use did not seem to impact blood pressure in any way. Even for those who regularly used cannabis throughout their life, there was no association with increased blood pressure.
These studies on cannabis and blood pressure certainly present a confusing picture. And researchers continue to investigate to try to find a way to clarify the role these cannabinoids play.
Risk factors for cannabis and blood pressure
Cannabis and its effects on the cardiovascular system remain unclear. Findings support both an increasing as well as a lowering effect on blood pressure. Randomized prospective trials are needed to answer many questions surrounding the therapeutic use of cannabis.
Those who are already using cannabis should also exercise caution in stopping the medication, as a sudden withdrawal from cannabis use could trigger increased blood pressure in some.
Because of these serious risk factors, anyone considering cannabis — particularly anyone who already has issues with pre-existing cardiovascular conditions — should be cautious and always check with their doctor before starting any cannabis regimen.