Cannabis
Can Cannabis Cause Seizures? Neurological Risks Explained
Lead Psychologist
Sep 10, 2025
Can cannabis cause seizures, or does it protect against them? The answer is complicated. On one hand, CBD-based medicines have been approved to reduce seizure frequency in epilepsy. On the other hand, clinical reports show cannabis—especially high-THC or synthetic forms—can trigger new-onset seizures, worsen existing epilepsy, or contribute to withdrawal-related seizures.1
This article unpacks the evidence on cannabis, seizures, and brain health—clarifying where risks lie, how dose and product type matter, and what patients and recreational users need to know.
Key Takeaways
Cannabis can cause seizures in certain situations, particularly with high-THC products, synthetic cannabinoids, or heavy long-term use.
Case reports document new seizures in healthy people after concentrated cannabis use.
Children are especially vulnerable to accidental ingestion–induced seizures.
CBD under medical supervision may reduce seizures, but paradoxically, even therapeutic trials report seizures as side effects in some patients.Mechanisms include CB1 overstimulation, altered excitability, and withdrawal-related hyperactivity.
Risk reduction means avoiding synthetic products, monitoring dose, and screening cannabis use when unexplained seizures occur.
When Cannabis Can Trigger Seizures
Clinical research shows that while many people tolerate cannabis without neurological complications, there are documented cases where it can directly trigger seizures, even in individuals with no prior epilepsy history.
One case report described a 20-year-old man who developed acute psychosis and new-onset seizures after smoking “moon rock” cannabis, a high-potency preparation with THC concentrations far beyond those in natural cannabis.2 This highlights a growing issue: modern cannabis products often contain far higher THC levels than in the past, raising neurological risks.
Another report involved a 44-year-old chronic cannabis user who developed late-onset epilepsy after 26 years of heavy marijuana smoking. MRI scans revealed structural brain changes consistent with chronic cannabis-related damage.3 In this case, cannabis did not just trigger seizures—it appeared linked to long-term neurological alterations that contributed to epilepsy development.
Taken together, these cases challenge the common perception of cannabis as harmless for the brain. While not everyone who uses cannabis will experience seizures, these examples show that dose, duration of use, and product potency all play crucial roles in determining risk.
Synthetic Cannabinoids
While natural cannabis carries some seizure risk, synthetic cannabinoids (often sold as “Spice” or “K2”) are far more dangerous. These laboratory-made compounds bind to the CB1 receptor much more strongly than THC, producing unpredictable and often toxic effects.
A case series reported two patients with no prior neurological disease who experienced their first generalised tonic-clonic seizures after smoking Spice.4 Unlike natural cannabis, these synthetic blends are often contaminated, vary widely in potency, and may overwhelm the brain’s endocannabinoid system.
A systematic review confirmed this pattern, showing that seizures occur in 5–15% of emergency department visits linked to synthetic cannabinoid intoxication.5 This rate is dramatically higher than that seen with natural cannabis. The mechanism is thought to involve excessive CB1 receptor activation and potential direct neurotoxicity.
For users who believe cannabis is a “safer alternative” to alcohol or other substances, it’s crucial to distinguish between plant-derived cannabis and synthetic products. The latter are consistently linked with severe neurological outcomes, including seizures, psychosis, and even death.
Table 1. Comparing Seizure Risks
Factor | Natural Cannabis (THC/CBD) | Synthetic Cannabinoids (Spice, K2) |
Seizure incidence | Rare, case reports and limited studies (0.7–1.2%) | Common, 5–15% of ER cases |
Mechanism | Dose-dependent CB1 activation; CBD may offset risks | Potent CB1 overstimulation; unpredictable composition |
Potency | 5–30% THC typical; CBD varies | Often >50× THC potency equivalent |
Population risk | Chronic heavy users, pediatric accidental ingestion | Any user, even healthy adults |
Clinical outcome | Seizures, sometimes reversible with abstinence | Seizures, psychosis, cardiovascular collapse |
Pediatric Cannabis Seizure Cases
One of the most concerning areas of cannabis-related seizure risk involves children. With edibles and high-potency products becoming more widely available, accidental ingestion among children has increased—and seizures are one of the most serious outcomes.
A report documented two paediatric cases where children presented in emergency rooms with new-onset seizures after cannabis ingestion.6 Neither child had a seizure history, underscoring that cannabis itself can act as a neurological trigger in vulnerable populations.
Another case series reinforced these findings, showing that accidental ingestion of cannabis can produce dose-dependent seizure severity in children. At higher THC concentrations, some children developed status epilepticus, a life-threatening condition involving prolonged seizures.7
This is particularly important because children have developing nervous systems. Their brains are more sensitive to chemical interference, meaning the same dose of THC that might make an adult drowsy could provoke seizures in a child.
Clinically, this evidence means that emergency physicians must consider cannabis intoxication in the differential diagnosis of unexplained paediatric seizures. Parents and carers also need to treat cannabis products—especially edibles—with the same caution as prescription medications, storing them securely and out of children’s reach.
Preclinical Evidence of Cannabis as a Proconvulsant
Animal studies give us important clues about how cannabis can trigger seizures at the neurological level. These controlled experiments show that cannabinoids can directly influence brain excitability and seizure thresholds.
One of the earliest studies, conducted in the 1980s, found that intravenous THC in pigeons caused electroencephalogram (EEG) changes that lowered the seizure threshold and increased seizure susceptibility.8 THC disrupted both monosynaptic and polysynaptic reflexes, which play a role in how electrical signals travel through the nervous system. This provided some of the first neurophysiological evidence that cannabis may act as a proconvulsant at certain doses.
More recent work confirmed that these effects are not limited to one species. A 2019 study found that prolonged exposure to THC-containing extracts increased seizure susceptibility in a species-specific way.9 In some animals, seizure risk rose significantly, while others showed less susceptibility. This variability suggests that both genetics and neurobiology influence how cannabis affects seizure activity.
Taken together, these preclinical studies support what clinicians have observed in humans: cannabis has a biphasic effect. At lower doses, some cannabinoids may protect against seizures, but at higher or prolonged exposures, THC in particular can destabilise brain networks and increase seizure risk.
The Cannabis–Epilepsy Paradox
Perhaps the most confusing part of the cannabis–seizure relationship is that cannabinoids can act as both treatments and triggers. Nowhere is this clearer than in epilepsy research.
A landmark clinical trial of CBD in patients with treatment-resistant epilepsy showed a 39% reduction in seizure frequency compared to placebo. This was a breakthrough finding that helped pave the way for Epidiolex, the first FDA-approved CBD-based epilepsy medication.10
However, the same study also reported that 11% of participants developed seizures as adverse events during CBD treatment. In other words, while many patients improved, some paradoxically worsened.
This paradox was reinforced in a Phase III trial studying CBD for Lennox-Gastaut syndrome, a severe childhood epilepsy. While CBD significantly reduced seizure burden overall, 6% of patients experienced status epilepticus, a serious and potentially fatal seizure complication.11
These findings demonstrate that cannabinoids cannot be viewed as uniformly protective against seizures. Instead, their effects depend heavily on dose, individual biology, and seizure type. While carefully prescribed CBD can be life-changing for some epilepsy patients, the very same compound may exacerbate seizures in others.
Mechanisms of Cannabis-Induced Seizures
Cannabis affects brain excitability in a biphasic way—meaning low doses and high doses can have opposite effects.
Preclinical studies in epilepsy models have shown that low doses of THC or CBD may suppress seizure activity, while higher doses can actually precipitate seizures.12 This dual effect helps explain why some people report cannabis reducing seizures, while others experience the opposite.
An expert review summarised this paradox, noting that cannabinoids follow a dose-dependent curve:
Low, controlled doses → may be anticonvulsant
High or uncontrolled doses → may become proconvulsant13
This dose sensitivity is particularly important in recreational use, where high-THC products and inconsistent dosing make seizures more likely compared to medically supervised CBD treatments.
Table 2. Biphasic Effects of Cannabis on Seizure Activity
Dose/Context | Potential Effect on Seizures | Mechanism |
Low-dose CBD (medical) | Reduced seizure frequency | 5-HT1A activation, neuroinflammation modulation |
Low-dose THC | Mixed effects; may be neutral or mildly anticonvulsant | Partial CB1 activation stabilizing excitability |
High-dose THC (recreational) | Increased seizure risk | Excessive CB1 stimulation lowering seizure threshold |
Chronic cannabis use | Neurological changes → possible epilepsy development | Endocannabinoid system dysregulation |
Synthetic cannabinoids | High, unpredictable seizure risk | Potent CB1 overstimulation, neurotoxicity |
This dose-response paradox is central to understanding cannabis’s neurological risks. Medical CBD is carefully dosed to stay on the anticonvulsant side, while recreational or synthetic use often crosses into the proconvulsant zone.
Seizures Linked to Cannabis Withdrawal and Hyperemesis
Most people think seizures occur only during intoxication. But clinical research shows they can also appear when someone stops cannabis after heavy use or during cannabis hyperemesis syndrome (CHS).
A comprehensive review of cannabis withdrawal noted that in chronic users, the brain adapts to constant CB1 receptor stimulation. When cannabis is suddenly stopped, this leads to neural hyperexcitability, sometimes culminating in seizures.14 This is rare but has been documented in heavy, long-term users undergoing abstinence.
Similarly, cannabis hyperemesis syndrome (CHS)—a condition marked by recurrent vomiting and abdominal pain in chronic users—has been associated with seizures in severe cases.15 The combination of electrolyte imbalance, stress on the nervous system, and endocannabinoid disruption can create a seizure-prone state.
Clinical red flags include:
Sudden seizures during cannabis withdrawal
Neurological complications in patients with CHS
Severe dehydration or electrolyte imbalances
Together, these findings show that seizures are not limited to cannabis intoxication—they can also appear during withdrawal syndromes and chronic cannabis complications.
Frequently Asked Questions (FAQs)
1. Can cannabis cause seizures in healthy people?
Yes. While uncommon, case reports indicate that high-potency cannabis can trigger seizures even in individuals without a prior seizure history. The risk is higher with concentrated THC products and synthetic cannabinoids.
2. Does CBD prevent or cause seizures?
CBD (cannabidiol) has been shown in clinical trials to reduce seizures in drug-resistant epilepsy. However, some patients in these same studies experienced seizures as side effects, showing that outcomes depend on dose, medical supervision, and individual vulnerability.
3. Why are synthetic cannabinoids like Spice riskier?
Unlike natural cannabis, synthetic cannabinoids overstimulate CB1 receptors and have unpredictable potency. Emergency studies show seizures in 5–15% of cases, far higher than natural cannabis exposure.
4. Can children have seizures from cannabis?
Yes. Accidental ingestion of cannabis edibles or oils has been linked to seizures in children, even without a prior seizure disorder. Paediatric nervous systems are especially vulnerable to THC toxicity.
5. Can quitting cannabis cause seizures?
In heavy users, sudden withdrawal can lead to neural hyperexcitability and rare seizure cases. This is more likely in individuals with long-term, high-dose cannabis use.
6. What steps can I take to reduce the risk of seizures while using cannabis?
Avoid high-potency THC products and synthetics.
Never exceed medical doses if prescribed CBD.
Seek medical advice if you have a history of seizures.
If you are cutting back on heavy CBD use, keep an eye out for withdrawal symptoms.
Conclusion: Can Cannabis Cause Seizures? Understanding the Risks for Safer Choices
Therefore, can cannabis cause seizures? The evidence shows that, while CBD under medical supervision can help reduce seizure frequency, recreational cannabis—particularly high-THC products, synthetic cannabinoids, and chronic heavy use—can indeed trigger seizures in some people. The risk is not uniform but shaped by dose, product type, genetics, and existing neurological conditions.
For individuals struggling with cannabis use, or those worried about its effects on brain health, the path forward isn’t about fear—it’s about clarity. Knowing your real neurological risks allows you to make informed decisions that prioritise your mental stability and long-term health.
If you’ve experienced cannabis-related seizures, unexplained neurological symptoms, or difficulty quitting, reaching out for professional guidance can be life-changing. Combining medical care with supportive tools like the SunflowerSobriety app helps you track progress, manage cravings, and stay accountable to your recovery journey.
Sobriety isn’t just about saying no — it’s about saying yes to mental clarity, neurological stability, and a safer future.
Author: Nikola Kojcinovic
Psychologist | Specialist Writer in Psychology & Behavioural Science
