Cannabis contains two primary cannabinoids: tetrahydrocannabinol (THC) and cannabidiol (CBD). These two cannabinoids have different effects and applications – emerging research shows that THC may raise blood pressure, while CBD may have some use in lowering it.
In addition to THC & CBD there are estimated to be 100+ other cannabinoids present within the cannabis plant that are yet to be studied for their impact on the cardiovascular system.
Research is still in the very early stages and medical cannabis isn’t currently prescribed for blood pressure-related concerns, but the positive results so far call for more research into the topic. Some of the terminology around blood pressure and heart health can be complex, so it’s useful first to know exactly what blood pressure is and why monitoring it is so important.
What Is Blood Pressure And Why Is It Important?
Your blood pressure measures the force of your blood against the walls of your arteries. When you get your blood pressure tested, you’ll notice there are two numbers, i.e., 120/80 mmHg (millimetres of mercury). The first of these two numbers refers to your systolic pressure, while the second refers to your diastolic pressure.
Systolic pressure refers to your blood pressure when the heart beats or contracts, pumping blood around the body, and is usually the more important number of the two. Diastolic pressure is your blood pressure in between beats when your heart is at rest. A normal blood pressure reading is typically around 120/80 mmHg.
If your systolic pressure is above 120, your blood pressure is considered ‘elevated.’ If your systolic pressure is between 130 and 139 mmHg and your diastolic pressure is between 80 and 89 mmHg, you may be experiencing hypertension, which means blood pressure that is consistently high. Higher readings than this may indicate stage 2 hypertension and finally hypertensive crisis, which is a medical emergency.
These are general guidelines – ideal blood pressure is often different for one person compared to another. Hypertension also sometimes involves few to no symptoms, so it’s important to have your blood pressure checked regularly, especially if you’re over 40.
Does Medical Cannabis Have Any Positive Effects On Blood Pressure?
A recent randomised, controlled trial found some interesting results when measuring the effects of cannabidiol (CBD) on the blood pressure of 70 adults with hypertension. The researchers administered CBD over 2.5 weeks and found that, compared to the placebo group, the CBD formulation reduced the participants’ systolic and diastolic blood pressure.
In the study, the researchers used a special CBD formulation designed to increase bioavailability, meaning it may have more pronounced effects than other CBD formulations. Whether the potential positive effects on blood pressure also apply to other CBD formulations isn’t clear.
In a similar study from 2019, volunteers were given 600mg of CBD to see how it might affect their blood pressure. The researchers found that CBD may have reduced the participants' mean resting blood pressure after one measured dose, but that the effect didn’t persist with repeated doses.
The volunteers’ blood pressure during stress, however, was reduced with both the initial dose and repeated doses. This study also split participants into a placebo and non-placebo group, but the study is limited by its small sample size of only 26 participants. This means that the results might not apply to the broader population.
While these studies have found some interesting results, more evidence is needed before we can say that CBD is a viable treatment for high blood pressure. Similarly, there is also the potential of medical cannabis products to interact with prescribed anti-hypertensive and other important cardiac medications. It is important to discuss using medical cannabis with your GP before commencing treatment.
Does Medical Cannabis Have Any Negative Effects On Blood Pressure?
Much of the research around the potential risks cannabis might pose for heart health or blood pressure focus on smoking as a method of consumption. Doctors don’t recommend smoking medical cannabis, and instead will direct patients to use their cannabis flower with a medical cannabis vaporiser. This is because of the many well-documented negative health effects of smoke inhalation, which may include cardiovascular risks.
Regardless, it’s important to let your doctor know if you have any blood pressure issues before you start using medical cannabis. Some studies have shown that THC itself may temporarily increase blood pressure regardless of the method of consumption. Despite this, a recent survey found that cannabis use may not be linked to hypertension, but the authors acknowledge that more studies are needed to confirm this.
It is important to note that the TGA advises against THC use for patients experiencing unstable cardiovascular disease. This is due to the potential for THC to cause unwanted or unforeseen side-effects on an already strained cardiovascular system. In addition to this, there are also drug interaction concerns relating to many anti-hypertensive and anti-coagulant medications. It is important to discuss your intention to commence medical cannabis with your treating team before commencing treatment to ensure the risk does not outweigh potential-benefits.
When used with a doctor's guidance, medical cannabis is usually safe and well-tolerated. Serious complications with medical cannabis are very rare, but combining medical cannabis with other medications that alter your blood pressure may pose some risks. Your doctor will assess your current medications and explain to you any risks and interactions there might be with medical cannabis.
Is Medical Cannabis Safe For Me If I Have Blood Pressure Issues?
Current research suggests that CBD-only products may have some use in lowering blood pressure in people with hypertension, but studies are still in the early stages. Medical cannabis that contains THC may not be safe for people with blood pressure issues, but your doctor is the best person to discuss this with.
Medical cannabis affects everyone differently. If you’re interested in medical cannabis you can book an appointment with your healthcare provider or a medical cannabis clinic. A doctor will assess you and your health to determine whether medical cannabis is a safe option for you.