Can you overdose on medical cannabis? Here’s what you need to know

Why overdose awareness matters for medical cannabis 

On the 31st of August, International Overdose Awareness Day will be upon us. 

It’s a day of increasing importance with each passing year, as the opioid crisis rages on, and other drug-related harms continue to affect communities not just here in the UK, but globally. A day of remembrance, education, but also compassion. For the people no longer with us, and their families and friends who carry their loss. 

It is also a time to look forward, to have open discussion around the stigma and demonisation of people who use drugs, and to consider how informed, respectful dialogue can prevent harm - and hopefully, reduce the impact of drug-related deaths in the months and years to come. 

Why talk about cannabis overdose for Overdose Awareness Day?

The day addresses the full spectrum of substances, not just those with high fatality risks. 

Cannabis falls into the low-risk category. 

While there are zero confirmed cases of cannabis overdose-related fatalities, taking too much THC can certainly cause uncomfortable, sometimes even alarming side effects. And these side effects can be risky, especially if you have certain underlying health conditions. 

Heavy anxiety to the point of paranoia, confusion, tachycardia, dizziness, and nausea are all reported side effects of the overconsumption of certain cannabis products, and for some people, these symptoms can be severe enough to require medical attention. 

This is why all Releaf patients go through an extensive clinical assessment before starting treatment.

Here at Releaf, patient education is a key tenet of our approach. We believe that presenting both the therapeutic benefits and the potential risks of medical cannabis in an unbiased, scientifically backed way is essential to safe and effective treatment. 

Overdose vs taking too much: what’s the real difference? 

When most people hear the word “overdose”, they picture a life hanging in the balance. 

A frantic 999 call, the wails of an ambulance siren, paramedics trying with all their might to pull someone back from the brink. 

That is what it means in medicine: a level of a drug in the body so high it can shut down essential systems. Some substances can do that frighteningly fast. Cannabis is not one of them. 

There is no confirmed lethal dose for humans, and its active chemicals do not shut down the respiratory and central nervous system in the way opioids or strong sedatives can (or the opposite, when stimulants such as cocaine or amphetamines are taken).

But too much cannabis can still put you through an uncomfortable ride. An edible with more THC than you or your body is used to can take hours to slowly wear off, or a few extra puffs of your THC vape can leave you feeling unsettled, light-headed, and wishing you had stopped just a little sooner.

The effects are almost always non-life-threatening, but the experience can still be quite unpleasant and, for some, worrying enough to seek medical help. 

The trouble is, the term “cannabis overdose” gets thrown about far too often in online debates and articles. The almost 120-year-long campaign of disinformation surrounding the Cannabis sativa L. genus has left deeply held misconceptions that still shape public opinion today.

How does cannabis overconsumption differ from an overdose? 

• An overdose on opioids or stimulants can end a life within minutes if untreated 
• Overconsumption, however rough it feels at the time, will pass

One of the more common causes of taking too much THC is through the recreational use of edibles. 

These unregulated products are regularly mislabelled, and people who are inexperienced with cannabis often see them as an easier, safer way to try it, without realising just how powerful and slow-acting the effects can be.

And slow acting they are, which is an issue in itself. 

You see, it takes anywhere between 60 and 120 minutes for THC to pass through the digestive system and start imparting its effects, and a full three to four hours for those effects to reach their peak. 

So, people new to cannabis, and unaware of this timeline, may assume the dose was too small and take more, only to find themselves far beyond their comfort zone later on.

What happens if you take too much THC? 

You cannot fatally overdose on THC, but you can make yourself thoroughly miserable. It usually starts in the mind with a somewhat sudden jitter in your thoughts, joined by a creeping sense that something is slightly… off. 

And then perhaps your heart joins in with a drum solo you did not expect. That physical cue then adds to the creeping anxiety, causing what can only be described as a feedback loop of unease. This can then bring on feelings of nausea, cold sweats, and more uncomfortable head noise. 

While not life-threatening, these moments can be unsettling enough to send even the most confident cannabis connoisseur seeking clinical reassurance. How unpleasant it becomes depends on your body’s tolerance to THC, the amount of THC ingested, how you took it, and what else is in your system. 

If you are going through this right now, take a few long, deep breaths, try to relax your racing thoughts and heart rate, and take solace in the knowledge that this sort of reaction is not permanent. The intensity will slowly drop off as your body processes the THC, usually within 20 to 30 minutes if it has been inhaled, or an hour or two if you have taken it in edible form.

Cannabinoid hyperemesis syndrome explained (CHS) 

Cannabinoid hyperemesis syndrome, whilst quite rare, is a serious condition that affects some long-term, heavy cannabis users. It was only first described in the early 2000s (with the first diagnostic criteria being published in 2009), but over the past two decades, it has become increasingly recognised as a real health concern. 

What are the symptoms of cannabinoid hyperemesis syndrome?

The symptoms of CHS can mirror those of food poisoning or a regular stomach bug, resulting in it often going undiagnosed (or totally misdiagnosed), sometimes for months or even years. Many people undergo repeated tests, changes in diet, and courses of medication before the real cause is uncovered. 

The main symptoms to look out for are repeated bouts of severe vomiting, abdominal pain, and dehydration - usually setting in within 30 to 60 minutes after consuming THC. Many people also find that a hot shower or bath brings short-lived relief, though symptoms tend to return until cannabis use stops.

How long does it take to recover from cannabinoid hyperemesis syndrome?

Most people going through CHS find that they start to feel better within a day or two of stopping cannabis, but for others, full recovery can take a couple of weeks. 

Can CHS patients ever take THC products again without symptoms recurring?

For most, the answer is no, even after long periods of no THC use. Some people have reported tolerating very small amounts after months or years without symptoms, but the risk of relapse is high and unpredictable. But, it is important to keep in mind that rates of CHS are extremely low, even in recreational cannabis users with zero clinical oversight or guidance. 

All Releaf medical cannabis prescriptions are carefully planned to match the patient’s health needs, with dosing, product choice, and ongoing clinical oversight and guidance designed to minimise any risk of adverse effects.

Why cannabis-related death statistics are often misleading

From the available research, cannabis overdose, to put it quite bluntly, just doesn’t happen. The amount of THC that a person would need to ingest to reach a truly lethal level is so far beyond what any human could reasonably consume that it’s effectively impossible.

That said, official reporting doesn’t always reflect this fact. Not because people are dropping dead after smoking recreational cannabis, having a few too many puffs from a vape, or eating a 500 mg edible, but because of the way deaths have been reported (and sometimes, sensationalised). 

Why correlation isn’t the same as causation in cannabis overdose reporting

In most cases, “cannabis-related” simply means THC showed up in a toxicology screen. It doesn’t prove the substance caused, or even contributed to, the death. THC is a fat-soluble compound, which means it stays in the human system far longer than most intoxicating substances. 

This means that the person who passed away may have used cannabis days, even weeks, before a fatal accident. But cannabis is still listed in official reports, creating a misleading association that can skew statistics and reinforce misconceptions about its actual risk profile.

The same can be said for someone who has overdosed on a different substance. If THC does show up in their system, it is noted in the coroner report, but that doesn’t mean it had any bearing on the cause of death. In many cases, it’s simply recorded as part of the toxicology findings, with no direct link to the fatal event at all.

How does titration help prevent cannabis overdose symptoms?

Titration is just a fancy clinical term for the dosage method we suggest to all of our patients. 

In plainer terms, “Start low and go slow”. 

Over the first few months of treatment, doses and the prescribed medical cannabis products are fine-tuned, with the patient’s own experience guiding the way. 

This can involve balancing THC and CBD in a different ratio, choosing a new format, or changing how often it is taken, which helps ensure that patients find their effective dose size and timetable whilst lowering any risks of side effects or discomfort. 

Expert insight: Dr. Edith Israel on cannabis and overdose risk 

We asked Dr. Edith Israel, one of Releaf’s prescribing specialists, an experienced clinician with many years working in the substance misuse sector, for her thoughts.

“To date, there is no evidence, and no recorded deaths, directly from cannabis or cannabis overdose. Unlike opioids, which are more widely prescribed for pain management, death from cannabis overdose is virtually impossible.

That said, cannabis can be a contributory factor in some cases, including:

• Patients with substance misuse who sometimes combine it with other substances (poly-substance misuse)

• Accidental injuries, such as driving after cannabis use, where cognitive impairment may play a role

• Complications in people with underlying health conditions that can be exacerbated by cannabis use, such as cardiovascular disease

• Worsening of psychosis in individuals already living with severe mental illness that involves psychosis

This is why, at Releaf, every patient is assessed systematically and thoroughly during their initial consultation by a senior doctor. The assessment ensures that we screen for risk factors which may predispose a patient to complications from cannabis use. This allows us to prescribe safely and provide the right support for patients to manage those risks.”

How medical cannabis clinical supervision reduces risks 

There are more than a handful of differences between medical cannabis and its illicit, black market counterpart - not just in the products themselves, but also in their application and administration. 

The UK medical cannabis sector is one of the most highly regulated in the world, and Releaf is leading the way as the most trusted and fastest-growing private medical cannabis clinic. 

From the very start, we have worked hand in hand with the regulatory bodies to ensure that every single Releaf patient has access to not only a world-class clinical team, but also the safeguards, guidance, and follow-up care that make sure treatment is both safe and effective.

Want to learn more about the potential medical cannabis may hold for your health needs? Head over to our medical cannabis eligibility checker. It takes just 20 seconds to complete and is totally free.