It’s impossible to take a lethal dose of cannabis. Despite unpleasant THC highs and edible freakouts, there have been zero ever documented deaths from weed. But, physiologically speaking, why is cannabis so safe?
The body has both an endogenous network of cannabinoid receptors, called the endocannabinoid system, as well as an endogenous system of opioid receptors. In the case of an opioid overdose, the brain forgets to breathe because the drug depresses the pre-Botzinger complex in the brain stem, which causes breathing to slow down until the person stops breathing altogether and dies of oxygen deprivation. Opioids can also depress the regions of the brain regulating heart and blood circulation, causing blood pressure to drop to dangerous levels. Meanwhile, a deadly alcohol overdose occurs when the body can’t flush the alcohol from the liver and the chemical reaches and disrupts those same regions of the brain that regulate breathing and blood pressure, essentially causing them to shut down.
Cannabis, however, can’t do this. The body’s cannabinoid receptors are not in the brainstem, and so the regions that regulate breathing, blood pressure, or heart rate remain uncompromised by cannabis. Rather, the cannabinoid receptors are mainly in the areas of the brain that manage functions like cognition, movement, memory, and appetite.
Moreover, the brain manufactures pregnenolone, a hormone that negotiates marijuana’s intoxicating effects on the body. According to researcher Dr. Pier Vincenzo Piazza at the University of Bordeaux, when the brain is overstimulated by THC, the main psychoactive compound in cannabis, it also produces extra pregnenolone, which inhibits THC’s impact. The negative feedback loop could keep cannabis users from getting debilitatingly high.
Nonetheless, it’s still possible to get too high — to the point of experiencing psychosis, anxiety, or the inability to operate a car or heavy machinery. If you are too high, don’t freak out. First of all, remember you can’t die. Second of all, keep in mind these tips from Jane to make your trip go more smoothly. And know that it will end… eventually.