The key thing here is that cannabis is extremely safe to use for most people. In the context of deaths, allergies and risks, cannabis is many times safer than alcohol, our cultural favourite drug, which causes numerous overdoses each year.

Margin of exposure (MOE) is a scale used to classify the relative risk of drugs. It is calculated by a ratio of two different factors: the benchmark dose, which is the amount needed to become harmful; and the amount consumed by the population.

The smaller the MOE number is, the higher risk it carries to society (Dirk W. Lachenmeier and Rehm, 2015).

 A recent study categorised alcohol as a high-risk drug based on the ratio of intake to toxicity. 

Cigarettes fell into the risk category with an MOE of less than 100. 

All other drugs including opiates, cocaine, ecstasy and amphetamines exhibited MOE of greater than 100, safer than alcohol and cigarettes.

Cannabis exhibits an MOE of over 10,000, classifying it as exceptionally low risk in comparison to other commonly consumed drugs (Dirk W Lachenmeier and Rehm, 2015). 

Paracetamol, also known as acetaminophen, can be consumed every 4-6 hours in doses up to 60mg per kilo of body weight (mg/kg), reaching toxicity at 140mg/kg or 10g per day (Ye et al., 2018).

It is the second most common cause of liver transplantation worldwide and responsible for 56,000 emergency department visits and 500 deaths per year in the US (Caparrotta, Antoine and Dear, 2018; Kennon-McGill and McGill, 2018).

The average caffeine consumption is 140-180mg per day (~2mg/kg), with a lethal dose of approximately 367mg/kg in rats and oral doses over 2,000mg requiring hospitalization in humans (Fulgoni, Keast and Lieberman, 2015; Adamson, 2016; Willson, 2018).

Monkeys and dogs demonstrated even higher tolerability, with single doses of THC at concentrations as high as 3,000-9,000mg/kg of body weight proving non-lethal (Thompson et al., 1973). 

This would be comparable to a human who weighs 80kg having to orally consume 250,000mg-720,000mg of concentrated THC in one oral dose; a dose that would equate to between 250-750g of pure THC. 

Studies have highlighted anywhere between 14.6 and 66.3mg of THC being found in each gram of cannabis (Sheehan et al., 2019).

To reach this lethal dose threshold through cannabis smoking, 3,770g of cannabis at once, that is using a high THC estimate of 66.3mg/g of cannabis and 250,000mg as a lethal dose. 

Although it is rare for doses as high as these to be experienced, these are key signs of a THC overdose and the potential side effects which this may cause.



Mild hypothermia


Hyper-reactivity to stimuli


Characteristic huddled posture

Slow movements

Abnormal eating procedures


Table 4. Typical symptoms of cannabis intoxication (Thompson et al., 1973). 


The effects of cannabinoids are typically more potent in females (Thompson et al., 1973). As you can see, phytocannabinoids were proven to be extremely safe compared to other drugs and it would be difficult to overdose on THC.

If you would like to read more please buy your copy of The Cannamanual here.

We also have a course based on The Cannamanual which can be done here

The comparative safety of cannabis

Created On
August 2, 2021

Cannabis industry and energy usage

Chris Tasker

5 ways science can help your business