Cannabis-infused foods, commonly known as edibles, are a popular method of consumption, but they carry a unique risk profile compared to other forms. Edibles contain the psychoactive compound delta-9-tetrahydrocannabinol (THC) and are processed differently by the body, which can lead to unexpected physiological effects. One potential side effect is a notable drop in blood pressure, medically termed hypotension. A standard blood pressure reading below 90/60 mmHg is generally considered low, and this reduction can cause symptoms ranging from mild dizziness to temporary loss of consciousness. High doses of THC can indeed cause this hypotensive effect, especially in sensitive individuals.
How Cannabis Affects Blood Pressure
The primary mechanism behind the drop in blood pressure relates directly to how THC interacts with the body’s internal communication system. Tetrahydrocannabinol acts by binding to cannabinoid receptors, specifically the CB1 receptors, found throughout the central nervous system and the cardiovascular system. This interaction affects vascular tone.
Once activated, the CB1 receptors in the blood vessels signal for vasodilation, the widening of the blood vessels. When the vessels expand, the total resistance to blood flow decreases significantly. This reduced peripheral resistance means the heart does not have to work as hard, resulting in a decrease in overall blood pressure.
Although some users may experience a temporary increase in heart rate immediately after consumption, a subsequent and more sustained drop in blood pressure often follows. This delayed hypotensive effect is the primary concern, particularly with higher doses.
A direct consequence is the potential for orthostatic hypotension, a sudden drop in blood pressure that occurs when a person quickly changes position. Because the blood vessels are already dilated by the THC, the body’s natural response to compensate for this shift is impaired, leading to a temporary reduction of blood flow to the brain.
Pharmacokinetic Differences of Edibles
Edibles present a distinct risk because the body processes them differently than inhaled cannabis, which affects their potency and duration. When cannabis is eaten, the THC must travel through the digestive system before being absorbed into the bloodstream. This means the onset of effects is significantly delayed, often taking between 30 minutes and two hours to fully manifest.
During the digestive process, the absorbed THC is routed to the liver through first-pass metabolism. Enzymes in the liver, primarily from the cytochrome P450 family, convert delta-9-THC into a metabolite called 11-hydroxy-THC (11-OH-THC). This metabolite is notably more potent and capable of crossing the blood-brain barrier more easily than the original THC compound.
The presence of this potent metabolite contributes to the intense and sometimes overwhelming effects of edibles. Furthermore, the slow absorption and metabolic process result in a prolonged duration of effect, with effects often persisting for four to twelve hours. This extended duration means that if a person experiences a drop in blood pressure, the hypotensive effect is also sustained and cannot be quickly reversed.
The delayed onset is a common cause of accidental overconsumption, as users may mistakenly believe the initial dose was ineffective and take a second one. This “double-dosing” significantly increases the total concentration of THC and 11-OH-THC in the system, amplifying the risk of severe side effects like profound low blood pressure. The slow, erratic absorption and conversion to a more potent form make the physiological response to an edible highly unpredictable.
Recognizing and Addressing Hypotension
Recognizing the signs of a drop in blood pressure is crucial for managing the situation safely. The most common symptoms include feeling dizzy or lightheaded, especially when standing up quickly, which is indicative of orthostatic hypotension. Other typical signs are a sudden onset of fatigue, blurred or “tunnel” vision, and a feeling of paleness or cold sweat.
In more serious instances, the individual may experience syncope, the temporary loss of consciousness or fainting. This occurs because the blood pressure has dropped low enough to briefly restrict oxygenated blood flow to the brain. While a single fainting episode is usually not harmful, the risk of injury from falling is a serious concern.
If symptoms of low blood pressure begin, the immediate management step is to lie down and elevate the legs above the level of the heart. This action uses gravity to redirect blood flow back toward the brain and chest. Increasing fluid intake, especially water or an electrolyte drink, can also help to boost blood volume and gradually raise blood pressure.
Preventing this adverse effect relies on cautious consumption practices due to the unique pharmacokinetics of edibles. Users should always adhere to the principle of “start low and go slow,” beginning with a dose of 2.5 milligrams of THC or less. It is also important to avoid consuming edibles when already dehydrated or when taking other medications that are known to lower blood pressure, such as certain drugs for hypertension. Seek emergency medical attention if confusion is severe, symptoms persist for many hours, or if there is repeated or prolonged fainting.