Adults only (18+)

Can You Overdose on THC?

As cannabis products become more widely available and stronger in potency, more people are asking whether it is possible to overdose on THC. THC, or tetrahydrocannabinol, is the main psychoactive compound in cannabis responsible for the high. While it is often perceived as relatively low-risk, especially compared to substances like alcohol or opioids, high doses of THC can cause unpleasant and even harmful effects.

This article is for new users, people curious about cannabis safety and anyone unsure of how much THC is too much. We will explain what THC overdose looks like, who is most at risk and how to reduce the chances of having a bad experience.

What Does “Overdose” Mean?

The word “overdose” typically suggests a life-threatening event where too much of a drug overwhelms the body, often requiring emergency treatment. In the case of THC, overdose does not usually refer to fatal poisoning, but rather to consuming too much for your body to tolerate, leading to acute symptoms that can be very uncomfortable or distressing.

THC overdose is sometimes referred to as “greening out,” a term used to describe when someone feels unwell after taking more cannabis than their system can handle. This can include physical and psychological symptoms that may last for several hours.

Is It Possible to Die from a THC Overdose?

According to medical research and statements from the NHS and Public Health England, there are no confirmed cases of death solely from THC overdose. The human body has very few cannabinoid receptors in the brainstem, which controls vital functions like breathing and heart rate. This makes fatal overdose from THC alone extremely unlikely.

However, this does not mean THC is risk-free. In very high doses, particularly in edible or concentrated forms, THC can cause severe anxiety, panic attacks, confusion, hallucinations, vomiting or loss of coordination. These symptoms can be frightening, and in rare cases may lead to accidents, hospital visits or harmful behaviour.

How Does THC Overdose Happen?

Most cases of THC overdose occur when people consume more than their body can comfortably process, especially if they are new to cannabis or trying a product that is stronger than expected. This is particularly common with edibles, as they can take one to two hours to produce noticeable effects, leading users to take more before the first dose kicks in.

Other high-risk situations include:

Using high-strength THC concentrates such as oils or dabs
Mixing THC with alcohol or other drugs
Inhaling or ingesting multiple doses in a short period
Using cannabis in unfamiliar settings or under stress
Having a low tolerance, especially among first-time users

Symptoms of Too Much THC

The symptoms of THC overdose can vary based on how much was consumed, how it was taken and the user’s individual tolerance. Common effects include:

Severe anxiety or paranoia
Rapid heart rate or palpitations
Panic attacks
Nausea or vomiting
Dizziness or fainting
Confusion or disorientation
Visual or auditory hallucinations
Shaking or chills
Loss of coordination
Temporary loss of contact with reality

These symptoms are rarely dangerous on their own but can cause significant distress. In some cases, especially among teenagers or those with pre-existing mental health conditions, a high dose of THC may trigger a short-term psychotic episode, which should be assessed by a medical professional.

Who Is Most at Risk?

Certain individuals are more likely to experience strong or unpleasant reactions to THC. These include:

New or infrequent users
Young people, particularly teenagers
Those with anxiety, depression or other mental health issues
People using cannabis products with unknown strength or source
Individuals taking other medications or substances alongside THC

People with underlying heart conditions should also exercise caution, as THC can temporarily raise heart rate and blood pressure.

What Should You Do if You Take Too Much THC?

If you or someone you are with has taken too much THC, the most important thing is to stay calm. While the experience can feel overwhelming, the effects will usually pass within a few hours.

Find a quiet, safe place to rest
Stay hydrated and avoid further THC or other substances
Focus on breathing slowly and staying present
Talk to a trusted person if you are feeling panicked
Avoid driving, walking in busy areas or making big decisions

If symptoms include chest pain, difficulty breathing, hallucinations or signs of psychosis, it is best to seek medical help. NHS 111 can offer advice, or call 999 if someone is at risk of harming themselves or others.

How to Avoid Overconsumption

To reduce the risk of taking too much THC:

Start with low doses, especially with edibles or new products
Wait at least two hours before taking more
Know the THC content of your product and understand your tolerance
Avoid mixing with alcohol or other drugs
Use cannabis in a familiar and safe environment
Read packaging carefully and use products from regulated sources

The UK currently limits legally prescribed cannabis products to controlled doses, and over-the-counter products must contain no more than 1mg of THC per container. Any products exceeding this threshold are considered controlled substances under the Misuse of Drugs Act 1971.

What About CBD and Other Cannabinoids?

CBD, or cannabidiol, is another compound found in cannabis. It is non-intoxicating and has a different effect on the body. In some cases, CBD may help counteract the intensity of THC, though this depends on the ratio and individual response. Products containing both THC and CBD may be more manageable for some users, but medical guidance is always recommended.

Is There a Risk of Dependence?

Although THC does not lead to fatal overdose, it can still be habit-forming. Around 1 in 10 regular cannabis users may develop cannabis use disorder, which involves cravings, tolerance, and withdrawal symptoms. Long-term overuse can also affect mood, memory and motivation.

Being aware of your usage habits and setting limits can help reduce the chance of overconsumption or dependence over time.

Conclusion

While it is unlikely that you could fatally overdose on THC, it is absolutely possible to take too much and have an uncomfortable or frightening experience. Overconsumption can lead to a range of psychological and physical effects that may require support or medical attention. Being informed about your tolerance, using cannabis responsibly and understanding the strength of your product can help you avoid these risks and make safer choices.