Marijuana and "Spice" Can Cause Seizures, Study Says

22. 12. 2025

Research in Japan investigated the effect of high doses of THC and JWH-018 on mice.
It was confirmed that both compounds induce seizures.

While many studies suggest that marijuana may be effective in reducing seizures, new research warns that strong and synthetic forms of the drug have the opposite effect.

Researchers from the University of Tsukuba in Japan found that natural tetrahydrocannabinol (THC) - the psychoactive chemical in marijuana - and the synthetic cannabinoid JWH-018 caused seizures in mice.

Lead study author Olga Malyshevskaya and colleagues say their findings - published in Scientific Reports - should serve as a "public warning" about potential harm caused by high-potency and synthetic marijuana.

While marijuana remains the "most used drug" in the United States, it is becoming increasingly legalized in individual states for medical, recreational, or both purposes.

New Study by Olga Malyshevskaya's Team

The research also found that seizures can be triggered by JWH-018, an artificial cannabinoid that is the primary element of synthetic marijuana known as "Spice". The study suggests that widespread use of high-potency marijuana - containing large amounts of THC - may actually trigger seizures.

Image result for mice and cannabis

Seizure Frequency Higher with JWH-018

Scientists reached their conclusions by analyzing brain activity in male mice after administering THC or JWH-018.

THC was given to rodents at doses of 10 milligrams per kilogram (equivalent to approximately 0.8 milligrams per kilogram in humans) and JWH-018 was administered at 2.5 milligrams per kilogram (equivalent to approximately 0.2 milligrams per kilogram in humans).

The team implanted electroencephalography (EEG) and electromyographic electrodes into the mice's brains, allowing them to monitor any electrical activity related to seizures in response to the compounds.

The movement and behavior of rodents were also monitored by video.

The study showed that mice experienced seizures shortly after administration of both THC and JWH-018, although the frequency of seizures was significantly higher with JWH-018.

Seizure-related brain activity persisted for 4 hours after administration of each compound, the team said, but returned to normal by the next day.

Interestingly, researchers found that pre-treatment of mice with AM-251 - a compound that binds to cannabinoid receptors 1 - prevented seizures in response to THC and JWH-018.

The team suggests that cannabinoid receptor antagonists could be useful for preventing seizures in cases of marijuana overdose

Study Warns of Potential Threats

According to researchers, their results provide "strong evidence" that plant and synthetic cannabinoids have the potential to trigger seizures.

"On the other hand, a significant portion of literature describing cannabinoids in animal models shows predominantly anticonvulsant effects," the authors state.

"However, few of them used EEG recordings to evaluate epileptic events, and many of them induced seizures either electrically or pharmacologically," they add.

The team points out that the THC and JWH-018 doses used in the study were high and may not represent doses commonly encountered in human recreational or medical use.

"In the future, it would be interesting to also test lower doses typically used medicinally or recreationally to determine if this effect is reduced or lost," the scientists claim.

Nevertheless, they believe their findings should be considered a warning about the potential dangers of cannabinoids, especially synthetic marijuana.

"Our study is very important because we are not particularly aware of the effect of cannabinoids. People see marijuana as a soft drug without dangerous health effects."

Source: article, image: themindunleashed.com;zentype.com