Chronological summary of clinical reports and surveys on the use of cannabinoids for epilepsy (1949–2015)

ReferenceStudySubjectsStudy DetailsResultsAdverse Effects
Davis and Ramsey (1949)Case series of 5 institutionalized children with mental retardation and epilepsy5Treated for 10 weeks with two isomeric-3 homologs of THC3 patients responded at least as well to their previous AEDs, the remaining 2 had significant decrease in seizuresNone reported
Consroe et al. (1975)Case study of a 24-year old male with refractory epilepsy1Patient would self-treat with 2–5 joints per night while continuing to take prescribed medicationsNearly seizure free with daily marijuana use in tandem with prescribed AEDsNone reported; patient was not able to completely control seizures on marijuana alone
Mechoulam and Carlini (1978)Placebo-controlled trial in epileptic patients9 total; 4 treatment, 5 placeboTreated with 200 mg of CBD in tandem with prescriptions for 3 months2/4 treatment group were seizure-free for the duration of the study; 0/5 placebo group had seizure improvementNone reported
Cunha et al. (1980)Placebo-controlled trial in teenagers and adults with TLE15 total; 8 treatment, 7 placeboTreated with 200–300 mg CBD or placebo per day for up to 4.5 months4/8 were seizure-free for the duration of the study; 3 others showed partial improvementSomnolence in some participants
Ames and Cridland (1986)Placebo-controlled trial in patients with uncontrolled seizures12 total; 6 treatment, 6 placeboTreated with 200–300 mg CBD or placebo per day for 1 monthLittle difference was reported between the treatment and placebo groups, although not much detail was givenSomnolence was reported as a side effect for some participants
Gedde and Maa (2013)Survey of parents of pediatric epilepsy patients who had been taking Realm Oil as a therapeutic option. Diagnoses included Doose, Dravet, and Lennox-Gastaut, as well as other refractory epilepsies11Realm oil (extract of 16:1 CBD cannabis plant) was given as a therapeutic option for at least 3 months. Average dose was between 4–12 mg/kg per day.11/11 patients experienced a reduction in weekly motor type seizure frequency; 8/11 experienced almost 100% reduction; 1/11 had a 75% reduction; 2 reported 20–45% reductionSedation and unsteadiness
Porter and Jacobson (2013)Survey was conducted of parents who had children with epilepsy who were currently using CBD-enriched cannabis products19Parents of pediatric epilepsy patients were surveyed on their children’s seizure frequency and duration16/19 responders reported a reduction in seizure frequency while children were taking medical marijuana; others reported beneficial effects like improved sleep and moodDrowsiness and fatigue were reported by some parents
Devinsky et al. (2014b)Prospective observational study including both children and adults with treatment-resistant epilepsies where CBD treatment was added to their daily AED regimen23Epidiolex (98% CBD oil) was given to patients for 3 months in tandem with previous prescriptions at a maximum dose of 25 mg/kg per day9/23 patients experienced >50% reduction in seizures; median reduction in seizures 32% for all patients; 1/23 had increased seizure activitySomnolence and fatigue
Friedman et al. (2014)Drug-drug interaction trial between Epidiolex (CBD) and clobazam in epileptic patients33 total; 17 CBD treatment, 16 clobazam controlTreated with CBD 25 mg/kg per day in tandem with clobazamA median change in AED serum levels was found for clobazam of 8.3%. 7/17 patients taking clobazam required a clobazam dose reduction owing to a drug-drug interactionNone reported
GW Pharmaceuticals plc (2015)Press release providing safety and efficacy data for Epidiolex treatment trials58Epidiolex (98% CBD oil) was given to patients for at least 12 weeks in tandem with their previous prescriptionsMedian reduction in seizure frequency was 43% for all patientsFatigue, somnolence, diarrhea, and changes in appetite were observed in some patients
Maa and Figi (2014)Case study of a 5-year old female with severe Dravet syndrome1Patient was given low dosage of sublingual preparation of low THC, high CBD marijuana extract daily>90% decrease in total seizures after 3 months of treatment; patient was able to wean off of previously prescribed medicationNone reported
Geffrey et al. (2015)Drug-drug interaction trial between CBD and clobazam in patients with refractory epilepsy25 total; 13 CBD treatment, 12 clobazam controlTreated with CBD 25 mg/kg per day in tandem with prescribed clobazam for 4 weeks11/13 patients experienced a 50–55% decrease in seizure activity; 
2/13 patients had an increase in seizure activityDrowsiness, ataxia, and irritability were observed in some patients
Hansen et al. (2015)Survey conducted at University of Alabama at Birmingham and Children’s of AL medical centers on the relationship between socioeconomic status and recipients of CBD oil epilepsy trials23Questions asked on household income, level of education, and medical insuranceRacially/ethnically monolithic (white)N/A
Majority pediatric (52.2%)
Majority female (62.2%)
Private health insurance (65.2%)
Medicaid or state insurance (26.1%)
Household income >50–60K (70%)
Household income >100K (28.6%)
“Special education until 21 program” (72.7% adults)
Oldham et al. (2015)Observational study of children and adolescents who received Epidiolex as an addition to their daily AED regimen25Participants were treated with up to 25 mg/kg per day of Epidiolex (98% CBD oil) for up to 12 months. Baselines were checked at 3 months and 12 months.3 months:Food aversion, diarrhea, changes in diet, or weight loss
32% of patients had a more than 50% seizure reduction
12 Months:
40% of patients (10) had above 50% seizure reduction
Press et al. (2015)Retrospective survey on pediatric patients with varying types of epilepsy who were taking oral cannabis extracts75Survey conducted on seizure frequency and duration57% of responders reported improvement of seizure duration and frequencyNone reported