This is one of the big unknowns. “It is important to remember that there is currently very little scientific evidence to support cannabis oil containing both THC and cannabidiol as a treatment for epilepsy,” said the charity Epilepsy Action, in a statement issued this month.
Not yet. In April the US Food and Drug Administration recommended the approval of a drug called Epidiolex for Lennox-Gastaut syndrome and Dravet syndrome. Its active ingredient is cannabidiol, and final approval is due at the end of this month.
Are there any cannabis-based epilepsy drugs on the market?
The situation is less clear when it comes to the use of commercial cannabis oils to control seizures, where the evidence is mainly anecdotal, and the oils can contain differing concentrations of cannabidiol and THC.
However, it is possible the drug is not as effective as cannabis oil containing THC, says Nutt. For example, the cannabis oil used to treat Billy Caldwell, the boy at the centre of the recent cannabis oil confiscation furore, contained cannabidiol and a low dose of THC, because cannabidiol alone did not stop all his seizures.
Is it legal?
What is the evidence that cannabis oils can help treat epilepsy?
Outside of these two disorders, CBD’s effectiveness in treating seizures is uncertain. Even with Epidiolex, it is uncertain whether the anti-seizure effects can be attributed to CBD or some other factor.
Clinical research has shown that CBD oil can trigger side effects. Severity and type can vary from one person to the next.
Cathy Wong is a nutritionist and wellness expert. Her work is regularly featured in media such as First For Women, Woman's World, and Natural Health.
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CBD oil can interact with certain medications, including some drugs used to treat epilepsy. CBD inhibits an enzyme called cytochrome P450 (CYP450), which metabolizes certain drugs. By interfering with CYP450, CBD may either increase the toxicity or decrease the effectiveness of these drugs.
CBD shows promise in the treatment of anxiety disorders, suggests a 2015 review of studies in the journal Neurotherapeutics. According to the investigators, CBD demonstrated potent anxiolytic (anxiety-relieving) effects in animal research, albeit with counterintuitive results.
There is some evidence that CBD interacts with seizure medications such as Onfi (clobazam) and boosts their concentration in the blood. Further research is needed.