Cannabis, often referred to as weed, is a plant containing various chemical compounds known as cannabinoids. The two most well-researched and prominent cannabinoids are tetrahydrocannabinol (THC) and cannabidiol (CBD). These compounds interact with the body’s endocannabinoid system, a complex network that helps maintain balance across various bodily functions, including mood, pain, and immune response. Understanding how THC and CBD affect this system can provide insight into the plant’s physiological impacts.
The Immediate Heart Rate Response
Contrary to what some may assume, cannabis typically leads to an increase in heart rate, a condition known as tachycardia. This rapid increase can begin within minutes of cannabis use, especially when inhaled. The heart rate can rise by 20 to 50 beats per minute, and these effects may persist for up to three hours. While some individuals might experience a feeling of relaxation, physiologically their heart rate is elevated. Studies show acute cannabis use can push heart rates over 100 beats per minute, the threshold for tachycardia, an effect observed across different consumption methods, including smoking and edibles.
How Cannabis Affects the Cardiovascular System
The physiological changes in heart rate following cannabis use are largely mediated by how cannabinoids, particularly THC, interact with the endocannabinoid system, primarily binding to CB1 receptors found in the heart and blood vessels. This interaction activates the sympathetic nervous system, often referred to as the “fight or flight” response, while simultaneously inhibiting the parasympathetic nervous system. The sympathetic nervous system activation contributes directly to the observed increase in heart rate and myocardial oxygen demand. While THC is the primary driver of these heart rate increases, CBD’s role is complex, but it does not typically cause the immediate heart rate increase seen with THC.
Beyond Heart Rate: Other Cardiovascular Considerations
Beyond its impact on heart rate, cannabis can affect other aspects of the cardiovascular system, including an initial, transient drop in blood pressure upon standing (orthostatic hypotension) that can occur, followed by an increase. Some studies indicate that smoking cannabis can cause an immediate increase in blood pressure due to temporary blood vessel constriction. However, cannabis, particularly THC, is also recognized for its vasodilatory properties, meaning it can cause blood vessels to widen, which can improve blood flow. The overall impact on blood pressure can be mixed and may vary. Heavy cannabis use has been linked to risks such as high blood pressure, and the effects of cannabis smoke on endothelial cells, which line blood vessels, are a concern as they may be similar to tobacco smoke and can contribute to coronary artery disease over time.
Factors Influencing Individual Responses
An individual’s cardiovascular response to cannabis can be influenced by several factors, with the dose of THC playing a significant role as higher doses generally lead to more pronounced effects on heart rate and blood pressure. The method of consumption also matters; inhaled cannabis typically produces a faster onset of effects compared to edibles, which can take up to 90 minutes for effects to be felt. Individual tolerance to cannabis can also affect the response, with frequent users potentially experiencing less frequent or less intense heart rate increases over time. Pre-existing cardiovascular conditions, such as heart disease or hypertension, can increase the risk of adverse cardiovascular events. The presence of other cannabinoids and terpenes in the cannabis product can also modify the overall effect.