More Research on Cannabidiol & Seizures

flaskSeveral new studies provide encouraging results about the use of cannabidiol (CBD) oil to treat seizure disorders that are not controlled by other medications. Research also, however, points toward important cautions.

Already in 2016,at least nine studies have been published on CBD and seizures. Two 2016 studies, one from Israel (Tzadok et al.,, 2016) and one the United States (Devinsky et al., 2016) are generally reporting particularly encouraging results. This is not to say the others are negative, just less relevant. The two discussed here are important because they include some results from fairly large samples of human participants, and help clarify a more realistic picture of potential risks and benefits. The American study included 214 children, and the Israeli study included 74. Both studies only included patients whose seizures were not adequately controlled by other anticonvulsant medications.

It is important to remember that neither study included a control group of similar patients that did not receive CBD and that those involved in the study were aware of when the patient received the CBD. As a result, these studies do not meet the strictest scientific standards for testing the effectiveness of drugs. Future studies might adopt stronger designs such as a matched control group, double-blinded study or a time series or multiple-baseline design that would eliminate the need to establish a matched control group. Nevertheless, measures such as the frequency of seizures are fairly objective and somewhat resistant to placebo effects.

In any case, here are some findings from these studies:

Overall, the safety of the CBD looked very good, but it was not problem free. Most side effects were minor, but a small number of patients had more serious problems while taking CBD. The studies’ designs didn’t really allow a determination if these serious health problems were caused by CBD or just happened by random coincidence. This is where a control group may have been useful, because it would have allowed the researchers to compare the problems encountered by those receiving CBD with problems encountered by similar participants who did not recieve CBD.

Previous studies have reported that CBD can interact with other medications, for example Clobazam. As a result, observed side effects were not directly caused by CBD but rather because CBD increased Clobozam levels and that caused side effects.

In my opinion, the important point here is that CBD is a drug that has great potential but needs to be taken seriously as a drug. If families are using it with a medically fragile child or adult, it is important that they do so under medical supervision or at least in close cooperation with the patient’s doctor. Testing to determine to what extent, if any, the CBD may be affecting other medications is one important reason for this, but there are also others.

Another important point for families is that many sources of CDB that are commercially available cannot be trusted to provide the amount of CBD advertised or to be free of other substances that may raise safety concerns. As Devinsky pointed out, an FDA study in 2015 found 33% of over-the-counter CBD oil products contained no CBD (also see, Press et al., 2015). In addition, this study found that many other products did not contain the amount of CBD that was claimed (often it was much less than the amount claimed). This points out the importance of ensuring that any CBD oil used comes from a reliable source or is tested for potency by a properly run laboratory. Using a poor product can (1) waste a lot of money, (2) fail to help the patient, (3) lead to a false conclusion that CBD can’t help, and, most importantly, and (4) can harm the individual taking it.

Overall, both studies reported that significant improvements for many participants. The Devinsky study found that with daily doses of 2 to 5mg / Kg of body weight:

For all seizure types, 51 (37%) of patients had a reduction of 50% or more, 30 (22%) patients had a response of 70% or more, and 11 (8%) had a response of 90% or more. Of the 32 patients with atonic seizures, 18 (56%) patients had a reduction of 50% or more and five (16%) patients became seizure free of this seizure type. Of the 65 patients with tonic seizures, 26 (40%) patients had a reduction of 50% or more and seven (11%) patients became free of this seizure type and, for the 89 patients with tonicclonic seizures, 30 (34%) had a reduction of 50% or more and eight (9%) became free of this seizure type.

This suggests that CBD may have a particularly good application to patients with drop seizures.Considering that these are all patients with intractable epilepsy, these are very encouraging results.

The Tzadok study also reported very encouraging results. This study collected results from various centres and dosage levels were more variable and often higher (mean 4.3 mg/Kg body weight, but some received more than 10 mg/Kg.  These researchers found:

Most of the patients (66/74, 89%) reported some reduction in seizure frequency: 13 (18%) had 75–100% reduction, 25 (34%) had 50–75% reduction, 9 (12%) had 25–50% reduction, and 19 (26%) had <25% reduction.

In addition, this study reported that more than half (59%) of patients improved in ways other than seizure reduction, such as improved sleep quality, behaviour, language and communication, alertness, and motor skills.

Both studies also reported small numbers of patients whose seizures increased or got worse.The design of these studies, however, did not allow a determination of whether these worsening seizures were the result of CBD treatment or not.

The Tzadok study specifically indicated that it included children with genetic syndromes and that as a group, they also benefited from treatment. Neither study specifically mentioned patients with MECP2 Duplication Syndrome, though it is likely that one or more was included. Anecdotally, I have heard from a handful of families who have tried CBD with their family members and the results have been mixed. (if their are other families who would like to confidentially share their experiences with CBD in MECP2 Duplication Syndrome, They can contact me at Some, but not all,  have reported a significant reduction in seizure activity and other benefits.

These studies also suggested that some types of seizures may be more effectively treated with CBD than others. However, of particular interest to those affected by MECP2 Duplication, there were good results with reduction of atonic seizures and  myoclonic spasms, and as a group patients diagnosed as having Lennox-Gastaut syndrome responded well.









Devinsky, O., Marsh, E., Friedman, D., Thiele, E., Laux, L., Sullivan, J., et al. (2016). Cannabidiol in patients with treatment-resistant epilepsy: an open-label interventional trial. Lancet Neurology, 15(3), 270-278.

Tzadok, M., Uliel-Siboni, S., Linder, I., Kramer, U., Epstein, O., Menascu, S., et al. (2016). CBD-enriched medical cannabis for intractable pediatric epilepsy: The current Israeli experience. Seizure, 35, 41-44.


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