Fact or fiction: is there such a thing as a cannabis overdose?

Part of the controversy on this issue is likely to stem from a misunderstanding of terminology. So first of all we need to define what exactly is meant by “overdose”. If it is interpreted to mean a set of acute adverse health consequences of taking too much cannabis, then it does occur, and indeed most users will have experienced it at some point in their lives. By contrast, if an overdose is seen as an episode that can result in death from poisoning, then no, this is not the case.

With respect to cannabis, the latter is not possible simply because the fatal dose of THC is higher than a person can realistically consume. Perhaps people who talk about cannabis overdoses do so because they want to add a certain fatalism to cannabis use, but the fact is that in the cannabis-using community the terms for poisoning are different, for example a ‘white-out’, ‘whitey’ or ‘greening out’. In the hospital setting, it is referred to as cannabis intoxication, but more colloquially it can also be called heartburn or indigestion due to excessive cannabis consumption.

In 2019 in Catalonia, a total of 761 people went to hospital as a result of cannabis intoxication, i.e. 4% of all hospital emergencies attended in which the main diagnosis was drug-related. Also in 2019, the main source of poisoning leading to hospitalisation and accounting for 42.8% of admissions was alcohol at more than 8,000 people.

If you consider the most common situations in which cannabis intoxication occurs, there are two classic cases. Firstly, young people smoking after school. Secondly, a party or celebration where there is a delicious space cake, in other words a home-made cake baked with cannabis among other ingredients.

People who are not used to the effects of cannabis, i.e. who have no tolerance to its effects, are the most likely to suffer a cannabis overdose, known as “white-out. The issue of tolerance is discussed later on in this post. Plus, if you eat cannabis and aren’t careful and/or don’t remember what the dosage is (how much and what type of cannabis is in the cake), the chances of ending up with symptoms and needing medical help increase.

The most classic symptoms likely to occur in this unwanted situation include impaired mobility, nausea, vomiting, disorientation, paranoia, anxiety, panic attack, dizziness, delirium, hallucinations and increased heart rate or blood pressure. People may even faint. If this fainting lasts longer than five minutes, professional medical help should be sought.

A number of factors are important to consider in order to avert or reduce the likelihood of cannabis intoxication. It is also essential to find out the concentration of tetrahydrocannabinol (THC), in the product before measuring it out. The higher the concentration of THC in the product, the lower the person’s tolerance to its effects and the greater the possibility of overdosing. Drug tolerance is the body’s ability to cope with the drug’s effects so that it doesn’t affect the nervous system. Tolerance varies from individual to individual, i.e. no two people who take a substance have the same reaction to it. If someone is used to cannabis, their tolerance to high concentrations of THC is much higher than that of a person who consumes it only occasionally.

Furthermore, you need to have at least basic information on the absorption times of the substance depending on the route of consumption. Smoking, vaping, snorting concentrates (‘dabbing’) or ingesting the substance are by no means the same. The inhaled route has immediate effects while the digestive option is much slower, as the active ingredients of cannabis first have to be absorbed in the stomach, then pass through the liver and finally reach the brain. This can take between 60 and 90 minutes depending on whether the person has eaten a lot or a little, their constitution and metabolism and other variables. The effect can last up to 6 to 8 hours, although there are extreme cases in which it has lasted up to 12 to 24 hours. It is also worth noting that, once inhaled, retaining the smoke or vapour in the lungs does not lead to further absorption of THC. This is because THC is absorbed as soon as it enters the lungs through the pulmonary alveoli.

It is essential that at the time of consumption you do not have an empty stomach or have taken other drugs, especially ones that depress the nervous system such as alcohol. All these factors come into play in the equation for cannabis intoxication. In case of fainting, it is important not to give the person affected anything to eat or drink until they have fully recovered.

Of course, if someone in your immediate surroundings is in this situation, you should support them in order to ease their distress. If the person loses consciousness, it is crucial that they are placed in the recovery position so that they can breathe properly.

Turning to oral products containing cannabis, popularly known as cannabis edibles, it is recommended to start with a dosage of 5-10 mg of THC and wait 60-90 minutes before having more. Remember that we are talking about milligrams of THC in edibles that should not be mixed up with the weight of the edibles themselves, which can vary greatly depending on the form: cakes, biscuits, brownies, etc.

Much has been written about the possibility of ingesting certain products in order to counteract a white-out, but very little is known objectively speaking. A 2013 study showed that cannabidiol (CBD) helps to decrease the adverse effects of anxiety and paranoia when consumed at the same time as THC. Yet it is unclear whether it has the same effects if administered after THC. However, taking some CBD oil or a high-CBD strain prior to ingesting THC might be an effective remedy for an unwanted high. There is one important thing to keep in mind when caring for someone who is suffering from a cannabis overdose: under no circumstances should they be given mango juice! Mangoes contain a chemical called myrcene, and the terpenes in them can enhance and prolong the effects of THC.

In 2017, a Drug Enforcement Administration (DEA) publication stated that ‘No deaths from overdose of marijuana have been reported’. Yet it might happen in theory, and in fact has been studied. There is a unit of measurement known as the lethal dose (LD), which applies to any substance that people may consume and is calculated in relation to body weight. This measure is an indication of the lethality of a given substance. For example, for sugar the median LD is 30 g/kg and for table salt it is 12 g/kg. This means that a lethal dose of sugar for an 80 kg person is 2.4 kg, while for salt it is almost 1 kg. Heroin, by contrast, has a median LD (LD50) of 50 mg/kg by inhalation, but only 0.02 g/kg if taken intravenously.

At this point, the famous phrase popularised almost five hundred years ago by Swiss physician and alchemist Paracelsus, which is considered the basic principle of toxicology, comes to mind: ‘All things are poison, and nothing is without poison; the dosage alone makes it so a thing is not a poison’. In fact, you are more likely to remember his condensed principle that says: ‘The dose makes the poison’. Need more examples? The LD50 for water is about 6 litres; for coffee, about 175 espressos, and for 40 proof alcohol, about 13 shots.

For cannabis, the amount needed for a lethal dose is colossal. David Schmader explains in his Weed, The User’s Guide: A 21st Century Handbook for Enjoying Marijuana (2017) that a person weighing about 75 kg would have to consume 750 kilos of cannabis in 15 minutes to overdose lethally. Most cannabis strains contain around 15-20% THC, i.e. 1 g of cannabis contains at most 200 mg of THC. It is virtually impossible to consume such a large volume of THC by inhalation. It is certainly possible to ingest more THC through swallowed edibles, but it should be noted that the most conservative estimates suggest an adult male would have to consume 50 grams of pure THC to have a 50% chance of dying. Even if a person were to ingest the most potent or concentrated cannabis edibles, they would be more likely to die sooner from over-consumption of sugar and salt than from an overdose of THC. To be sure, someone who is very disturbed might consider injecting a lethal amount of pharmaceutical THC, but this is a rather far-fetched scenario.

When someone experiences an overdose or indigestion from excessive cannabis use, it can be physically and emotionally very unpleasant. The treatment for heavy marijuana use is simply to wait until the effects wear off, and this can be a matter of hours. One thing that can really make a difference is the company and setting in which the intoxicated person has the experience. This means going to a quiet, safe space, unbuckling belts or other items of clothing that are tight or uncomfortable, trying to breathe calmly, relaxing, being in the company of a person you trust, and perhaps holding hands to stay connected. It may also be helpful in some cases to drink some water to keep hydrated and to eat something to raise blood sugar levels.

Other types of acute adverse reactions, such as the ones that can happen to young people with pre-existing medical conditions that are triggered by cannabis use, have not been addressed so far. They are rare cases or are not typical reactions to cannabis use. This happens when predisposed individuals experience an acute psychotic episode after cannabis use or in the case of people with cardiovascular problems, who might even have a heart attack. Similarly, overdoses related to the use of synthetic cannabinoids, which have caused fatalities, have not been discussed. This issue will be looked at in other posts on this website.

So now you know: to avoid all risks, it is better not to consume any cannabis at all. To reduce the risks, you should find out what you are using and do it in moderation and in a safe environment. Firstly, it is a good idea to start with a small amount and wait at least 15 minutes if inhaled, or two hours if taken orally. Check how you are moving around before you consider taking more. And if you have overdone it, make a note of what you have consumed, how and when. That way, next time you can do it in moderation. 🙂