Key points:
- THC is unlikely to cause seizures.
- THC is even used to manage seizures and may help those living with epilepsy.
- THC content in legal vapes is too little to cause severe issues like seizures.
In short, NO, legal THC vapes cannot cause seizers or seizures, as THC’s dosage is well within legal and safe limits. Moreover, CBD appears to prevent seizures (1).
As a physician, I often encounter questions about the potential neurological risks of cannabis and THC use. One concern that arises is whether vaping THC could trigger seizures.
The answer is not straightforward, as the relationship between THC and seizure activity is complex. While high doses of THC can have profound effects on brain function, it is essential to differentiate between the risks associated with high-potency cannabis and the reality of legally regulated THC vapes in the UK.
Legal THC vape products contain no more than 1 mg of THC per pack, alongside CBD and minor cannabinoids, making their effects vastly different from high-THC cannabis products commonly associated with neurological side effects.
THC, or tetrahydrocannabinol, interacts with the body’s endocannabinoid system, a network of receptors involved in regulating mood, cognition, and neurological stability. It primarily binds to CB1 receptors in the brain, which can influence neurotransmitter activity. In some cases, this interaction may lead to increased excitability in the brain, which has raised concerns about whether THC could act as a seizure trigger. However, research into this topic remains inconclusive.
Some studies suggest that THC has anticonvulsant properties, particularly when combined with other cannabinoids. In fact, cannabis-derived medications like Sativex, which contain both THC and CBD, have been prescribed for neurological conditions such as multiple sclerosis (2).
Seizures can have many triggers, including underlying epilepsy, metabolic imbalances, stress, and sleep deprivation. In some cases, individuals who experience seizures after using cannabis may already have an undiagnosed neurological condition. It is also important to consider the role of illicit and unregulated THC products, which can contain harmful additives or synthetic cannabinoids that pose additional risks.
In contrast, UK-legal THC vapes are subject to strict regulations. These products contain minimal THC, usually no more than 1 mg per cartridge or disposable pen. This amount is so low that it is unlikely to have any psychoactive or excitatory effects on the brain. Furthermore, these vapes often contain CBD, which is well known for its anticonvulsant properties. CBD is the primary active ingredient in Epidiolex, a prescription medication approved for treating epilepsy. Because of its ability to regulate brain activity and counteract some of THC’s more stimulating effects, CBD may actually reduce the likelihood of seizure activity rather than increase it (3).
For individuals with a history of seizures or epilepsy, caution is always warranted when introducing any new substance that affects neurological function. If you have a diagnosed seizure disorder, I would strongly advise consulting with a healthcare professional before using any THC-containing product, even one that meets UK legal standards.
From my perspective as a physician, the current evidence does not support the idea that UK-legal THC vapes pose a significant seizure risk. The minimal THC content, combined with the presence of CBD and strict regulatory oversight, makes these products fundamentally different from high-potency cannabis or illicit vape cartridges. In fact, these products are more likely to suppress or prevent seizures or convulsions.
However, as with any substance that interacts with brain chemistry, individual differences in response should not be ignored.
References
- Medical Marijuana | Seizure Treatment | Epilepsy Foundation [Internet]. [cited 2025 Feb 8]. Available from: https://www.epilepsy.com/treatment/alternative-therapies/medical-marijuana
- Sativex Oromucosal Spray – Summary of Product Characteristics (SmPC) – (emc) [Internet]. [cited 2025 Feb 8]. Available from: https://www.medicines.org.uk/emc/product/602/smpc#gref
- Abu-Sawwa R, Stehling C. Epidiolex (Cannabidiol) Primer: Frequently Asked Questions for Patients and Caregivers. J Pediatr Pharmacol Ther. 2020;25(1):75–7.
