Many wonder if it’s safe to smoke weed if you have high blood pressure. Cannabis (also known as marijuana or weed) is being used more often, both medically and recreationally.
Short-Term Effects of Weed on Blood Pressure
Smoking cannabis causes immediate effects on the cardiovascular (heart and blood vessel) system. Shortly after using cannabis, heart rate typically increases, and blood pressure can rise temporarily. For example, tetrahydrocannabinol (THC – the main psychoactive, or mind-altering, chemical in cannabis) can stimulate the “fight or flight” response, causing a burst of adrenaline and a faster heartbeat (tachycardia – an abnormally fast heart rate). This may lead to a brief spike in blood pressure (the pressure of blood against artery walls).
These short-term effects are often more pronounced in people who are new to cannabis or who use high doses. In some cases, after the initial spike, blood pressure might drop as the blood vessels relax; cannabis can cause vasodilation (widening of blood vessels), which sometimes leads to orthostatic hypotension (a drop in blood pressure upon standing up).
However, the immediate effect right after smoking is usually a rise in blood pressure and heart rate. Health authorities note that cannabis can make the heart beat faster and raise blood pressure immediately after use, which could be risky for people with already high blood pressure.
Long-Term Cannabis Use and Hypertension Risk
A key question is whether using cannabis regularly leads to chronic hypertension (long-term high blood pressure). Current research is mixed. Some recent studies in older adults did not find a higher rate of hypertension among regular cannabis users.
Longitudinal studies (those following people over time) reported no clear link between lifetime cannabis use and the development of high blood pressure. In fact, one study of patients over 60 using medical cannabis for three months found a modest reduction in 24-hour blood pressure readings.
Researchers observed that these older adults had slightly lower blood pressure, especially about 3 hours after using cannabis (which was likely for pain management). This suggests that in certain contexts (such as controlled medical use), cannabis might not worsen blood pressure and could even lower it.
That said, cannabis’s long-term impact on blood pressure can depend on the person and use pattern. Frequent cannabis users may develop tolerance to some of its effects. For instance, the rapid heartbeat effect of THC often diminishes with consistent use over days or weeks. This means a regular user might not experience as much of a blood pressure jump as a first-time user.
On the other hand, abruptly stopping heavy cannabis use (cannabis withdrawal) may cause a rebound increase in blood pressure in some cases. Overall, epidemiological studies (population studies) have found mixed results – some show no strong association between cannabis use and sustained high blood pressure, while others note potential risks. More research is needed to fully understand long-term effects, but so far cannabis does not appear to consistently raise blood pressure in the long run. This is in contrast to tobacco, which is firmly linked to chronic hypertension.
Smoking Pure Cannabis vs. Cannabis Mixed with Tobacco
How you smoke cannabis matters. In many places, especially in Europe, people mix tobacco with cannabis in a joint (a hand-rolled cigarette) or blunt. It’s important to separate the effects of cannabis itself from the effects of tobacco (nicotine) when mixed.
When cannabis is smoked without tobacco (pure cannabis), the immediate cardiovascular effects come from cannabis compounds (like THC) and the act of smoking. As noted, THC can cause a temporary rise in heart rate and blood pressure. Smoking also introduces carbon monoxide and other combustion byproducts that can lower the blood’s oxygen, causing the heart to work harder.
Cannabis smoke contains many of the same toxic chemicals as tobacco smoke, such as tar and carbon monoxide. These toxins can irritate blood vessels and may contribute to arterial stiffness (loss of artery flexibility) and endothelial dysfunction (impaired function of the blood vessel lining). Such changes make it harder for arteries to relax and could raise blood pressure.
Acute blood pressure spikes have been observed after smoking cannabis, likely due to these combined effects. However, unlike tobacco, cannabis does not contain nicotine, so it lacks the direct pressor (blood pressure raising) effect that nicotine causes.
When cannabis is mixed with tobacco, the effects on blood pressure and heart rate are amplified. Nicotine from tobacco is a powerful stimulant for the cardiovascular system. It causes the adrenal glands to release adrenaline (epinephrine), a hormone that makes the heart beat faster and blood vessels constrict (narrow) – this raises blood pressure significantly in the short term.
One study found that heart rate was highest when cannabis was used with tobacco, and blood pressure increased more with the combination than with cannabis alone. The researchers noted that mixing tobacco with cannabis could add to the cardiovascular risk of cannabis use. In other words, tobacco intensifies the stress on the heart and blood vessels.
People often add tobacco to cannabis to help it burn or due to habit, but it does not make you “higher” (more intoxicated) according to research. Instead, it just introduces nicotine’s harmful effects. It’s well known that cigarette smoking (because of nicotine) can immediately raise blood pressure and contribute to hypertension over time, so adding that risk on top of cannabis is especially concerning.
Health experts say smoking cannabis is not much different from smoking tobacco in terms of the stress it puts on the cardiovascular system. Therefore, for someone with high blood pressure, combining weed with tobacco is particularly risky. Avoiding tobacco (no nicotine) is crucial to minimize blood pressure spikes.
How Cannabis Influences Blood Pressure (Biological Mechanisms)
Cannabis affects blood pressure through several biological mechanisms involving the endocannabinoid system (the body’s natural system of cannabinoid receptors and signaling molecules). Here’s what happens in the body when cannabis is used:
- THC and Blood Vessels: THC (Δ⁹-tetrahydrocannabinol) binds to cannabinoid receptors (CB1 and CB2) found in the heart, blood vessels, and nervous system. Activation of CB1 receptors by THC can cause blood vessels to relax (dilate) in some parts of the body, which would lower blood pressure by reducing vascular resistance (resistance to blood flow). However, THC’s effects are complex. Research shows THC might also enhance vasoconstriction (blood vessel narrowing) under certain conditions. For example, in lab studies THC sometimes made blood vessels respond more strongly to a constricting signal. This dual action means THC can both lower or raise blood pressure depending on the context (which blood vessels are affected, and whether the person is sitting, standing, stressed, etc.). In the central nervous system, THC can activate the sympathetic nervous system (the “fight or flight” system), leading to the release of catecholamines like norepinephrine. This causes the heart to pump harder and faster, which tends to increase blood pressure. The net result for most users is an initial increase in heart rate and blood pressure, as the sympathetic effect dominates right after use.
- THC and Heart Output: THC also directly impacts the heart. It can increase cardiac contractility (how forcefully the heart squeezes) via CB1 receptors. A stronger heartbeat combined with faster rate pushes blood more forcefully through arteries, raising the systolic pressure (the top blood pressure number during a heartbeat). Over a short period, this increases the workload on the heart.
- CBD and Blood Vessels: Cannabis also contains cannabidiol or CBD, a non-psychoactive compound. CBD has almost the opposite effect of THC in many ways. Studies indicate CBD can cause vasorelaxation (relaxation of blood vessel walls). It helps blood vessels widen by acting on the endothelium (inner lining of vessels) and possibly through interacting with different receptors. CBD also has anxiolytic (anxiety-reducing) properties, which can lead to lower stress hormones and a modest blood pressure reduction in some situations. Some research found that CBD could lower blood pressure slightly, potentially by reducing anxiety and by sympathoinhibition (damping the sympathetic nervous system activity). Unlike THC, CBD doesn’t cause a high or significant heart rate increase. So, if a cannabis strain or product is high in CBD and low in THC, its effect on blood pressure might be minimal or even lowering. However, most people smoking weed recreationally are using high-THC strains, so they experience the THC-driven effects described above.
- Endocannabinoid System Balance: The body’s endocannabinoid system normally helps regulate cardiovascular function. It releases its own cannabinoids (like anandamide) that can influence blood vessel tone and heart rate. When cannabis is consumed, the plant cannabinoids (THC, CBD, etc.) hijack this system. THC’s stimulation of CB1 receptors in the brain can reduce peripheral vascular resistance (how constricted your blood vessels are) and lower blood pressure in some regions, but at the same time it may trigger reflex responses (like baroreceptor reflex, where the body tries to compensate for low pressure by increasing heart rate). This push-and-pull results in the complicated outcome we see: often a transient blood pressure increase followed by a possible decrease. The exact response can vary by individual. For instance, a person in a relaxed setting might mainly see vasodilation and feel lightheaded (lower pressure), whereas someone who becomes anxious after using cannabis might see a bigger jump in heart rate and pressure.
- Withdrawal and Other Factors: If someone uses cannabis very often, their body adapts (tolerance). Then if they suddenly stop, the endocannabinoid system might be temporarily overactive in the opposite way, possibly causing blood pressure to rise during withdrawal. Other factors like dehydration (cannabis can cause dry mouth and slight dehydration) and posture can influence the blood pressure response too.
In summary, tobacco/nicotine reliably raises blood pressure by directly constricting blood vessels and making the heart work harder. This effect is immediate and, with repeated use, contributes to long-lasting hypertension. There is no ambiguity about tobacco’s effect – it is consistently linked to higher blood pressure and cardiovascular risk. That’s why health guidelines universally advise people with high blood pressure not to smoke cigarettes. When considering cannabis use, adding tobacco will only increase the cardiovascular dangers.
What It Means for People with High Blood Pressure
Considering the evidence, what’s the bottom line for someone with hypertension who wants to smoke weed? Overall, caution is advised. Cannabis can cause spikes in blood pressure and heart rate in the short term, which can be risky if your blood pressure is already high. While cannabis might not cause chronic hypertension in the way tobacco does, the immediate effects could still pose a danger – for example, raising blood pressure to a level that could trigger a heart attack or stroke in vulnerable individuals. Health organizations note that smoking cannabis carries similar heart health risks as smoking tobacco. This is partly because of the combustion (smoke) and partly because of THC’s effects on heart rate and blood vessel tone.
For pure cannabis use (without tobacco), if someone with high blood pressure chooses to use it, they should be aware of these potential effects. Methods of consumption matter: smoking (inhaling combusted material) is harshest on the cardiovascular system. Alternatives like vaporizing or edibles might reduce some risks (by avoiding smoke), but THC will still have systemic effects. Any cannabis use should be discussed with a healthcare provider if you have hypertension, especially if you take blood pressure medications. THC can interact with blood pressure by either raising or sometimes unpredictably lowering it, and CBD can interact with drug metabolism.
Sources
- CDC – Cannabis and Heart Health (Centers for Disease Control and Prevention)
- American Heart Association – Marijuana and Heart Disease Risks
