No one has ever died from an overdose of cannabis.
In test animals researchers have tried to induce death with cannabis as a way to determine drug safety, as is standard in all medication. They have been unable to do so.
In theory, the LD-50 is about 1:20,000 to 1:40,000 in order to induce death. This means that a cannabis smoker would have to consume 20,000 to 40,000 times as much marijuana as is contained in one marijuana cigarette. Cannabis cigarettes weigh approximately .9 grams. A smoker would theoretically have to consume nearly 1,500 pounds of marijuana within about fifteen minutes to induce a lethal response.
Perry Solomon, MD
The WHO states that the LD (lethal dose) of Cannabis is 1/20000. So it is almost impossible to dy from overdose / intoxication . However, the THC can a five-fold increase risk of Myocardial Infarctions (MI) in the first hour after cannabis use (Lee & et al).
It is explained by the reduction in coronary blood flow in combination with reduced oxygen carrying capacity and potential systemic and coronary vasoconstriction that lead to an increase in myocardial oxygen supply-demand mismatch, resulting in ischemia. Patients at risk are those who are suffering from preexisting cardiac conditions such as stable angina are especially prone to develop symptoms.
Lee, J., Sharma, N., Kazi, F., Youssef, I., Myers, A., Marmur, J. D., … McFarlane, S. I. (2017). Cannabis and Myocardial Infarction: Risk Factors and Pathogenetic Insights. SciFed journal of cardiology, 1(1), 1000004.