CBD and Dravet Syndrome
FDA-approved pharmaceutical CBD cuts convulsive seizure frequency by roughly half in Dravet syndrome.
This article is for information only and is not medical advice. Talk to a doctor before using cannabis for a health condition, and do not stop or change prescribed treatment on your own.
Pharmaceutical CBD is the only cannabis-derived drug with solid randomized trial evidence for a specific seizure condition. It cuts convulsive seizures roughly in half in Dravet—real progress for a devastating childhood epilepsy. But it's not a cure, doesn't free most patients from seizures, and has serious drug interactions. Dispensary CBD oils are not the same thing and are not proven. This is genuinely a medical decision, not a wellness supplement choice.
Plain-language summary
Dravet syndrome is a rare, severe genetic epilepsy starting in infancy, most often caused by mutations in the SCN1A gene. Seizures are frequent and often triggered by fever or heat; most first-line antiseizure drugs fail to control them [1].
Cannabidiol (CBD) is a non-intoxicating compound from cannabis. A purified pharmaceutical form—sold as Epidiolex in the US and Epidyolex in Europe—has been tested in randomized, placebo-controlled trials in children with Dravet syndrome. In those trials, CBD roughly cut convulsive seizure frequency in half on average (median 43% of patients achieved ≥50% reduction), compared to about 13–27% reduction with placebo [2][3]. The FDA and European Medicines Agency approved it for Dravet on the strength of this evidence [4].
This article covers that specific pharmaceutical drug, at the doses studied, in this specific condition. It is not medical advice. Dravet syndrome is life-threatening. Treatment decisions belong entirely with a pediatric neurologist or epileptologist.
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⚠️ This article is not medical advice. Dravet syndrome requires specialist care. Do not start, stop, or change any medication without direct supervision by a qualified neurologist or epileptologist. Drug interactions between CBD and other antiseizure drugs are real and potentially dangerous.
What probably works (strong evidence)
Pharmaceutical CBD reduces convulsive seizure frequency in Dravet syndrome. Strong evidence
The pivotal trial (Devinsky et al., NEJM 2017) enrolled 120 children and young adults with drug-resistant Dravet. Participants received pharmaceutical CBD 20 mg/kg/day or placebo in addition to whatever antiseizure drugs they were already taking. Median convulsive seizure frequency dropped from 12.4 to 5.9 per month on CBD, versus 14.9 to 14.1 on placebo over a 14-week treatment period. Forty-three percent of CBD patients achieved ≥50% seizure reduction, compared to 27% on placebo [2].
A second randomized trial (Miller et al., JAMA Neurology 2020) tested lower doses (10 mg/kg/day and 20 mg/kg/day) against placebo and confirmed efficacy at both doses. The 10 mg/kg dose was associated with fewer adverse events [3].
On the basis of these trials, pharmaceutical CBD received FDA approval in June 2018 [4] and European Medicines Agency approval in 2019, specifically for seizures in Dravet syndrome.
Long-term extension data from open-label follow-up suggest the seizure-reduction effect persists in responders for at least 1–2 years, though some patients lose responsiveness over time [5].
What might work (weak or preliminary evidence)
Reduction in non-convulsive seizure types. Pivotal trials primarily measured convulsive seizures (myoclonic and generalized tonic-clonic). Dravet also involves other seizure types (focal seizures, absence-like episodes). Effects on these are less well characterized. Weak / limited
Caregiver-reported quality of life and global impression of improvement. In the pivotal trials, caregiver Global Impression of Change scores improved more on CBD than placebo [2][3]. However, these are subjective ratings prone to unblinding—caregivers can perceive side effects (somnolence, behavioral changes) that reveal treatment assignment. The difference between true therapeutic benefit and expectancy bias is hard to separate in open-label follow-up. Weak / limited
Non-pharmaceutical, cannabis-derived CBD products. Early observational studies of caregivers using whole-plant CBD-rich extracts (Press et al., 2015; Porter & Jacobson, 2013) reported seizure reductions [6][7]. These studies lack blinding, have no control group, and product contents were often unverified. They generated the hypothesis that later randomized trials confirmed, but they provide no evidence that a given dispensary oil will work or is equivalent to Epidiolex. Weak / limited
What doesn't work or has no good evidence
Complete seizure freedom. Seizure freedom on CBD is uncommon in Dravet. The goal in these trials was seizure reduction, not elimination. Most responders still experience multiple seizures per month, just fewer than before [2][3]. Strong evidence (for the negative claim)
Cognitive or developmental improvement independent of seizure reduction. No adequately powered trial has shown that CBD improves cognitive trajectory, school performance, or developmental milestones in Dravet syndrome beyond what is expected from seizure reduction alone. No data
Reduction in mortality or SUDEP risk. Dravet carries an elevated risk of sudden unexpected nocturnal death in epilepsy (SUDEP). No trial has been powered to detect whether CBD reduces this. No data
Equivalence of over-the-counter CBD oils to Epidiolex. Independent testing of dispensary and online CBD products has repeatedly found significant mislabeling of claimed CBD content, contamination, and occasional significant THC content [8]. There is no evidence that these products are bioequivalent to the pharmaceutical formulation used in trials or that they work. No data
'Entourage effect' claims that whole-plant or full-spectrum CBD extracts outperform isolate CBD in Dravet are popular online but not supported by controlled trials in this condition. Disputed
What we don't know
- Whether CBD's benefit is independent of a pharmacokinetic interaction with clobazam. CBD inhibits CYP2C19, raising levels of clobazam's active metabolite N-desmethylclobazam. Some of the clinical benefit attributed to CBD may come from higher clobazam exposure. Subgroup analyses suggest CBD works in patients not receiving clobazam, but the magnitude of the drug interaction effect remains unclear [9].
- The optimal long-term maintenance dose and whether tolerance develops. Trials were 14 weeks or less. What happens to seizure control over years of continuous CBD is unknown.
- Whether early CBD initiation changes long-term cognitive or mortality outcomes. Current trials only measure short-term seizure counts, not whether early intervention with CBD prevents later developmental decline or SUDEP.
- How pharmaceutical CBD compares head-to-head with fenfluramine or stiripentol. Indirect evidence suggests fenfluramine may produce larger seizure reductions, but there are no direct comparative trials [10].
- Whether any non-pharmaceutical CBD product can reliably reproduce trial results. Because products vary widely in content, no evidence base exists.
- The mechanism by which CBD reduces seizures in Dravet. The target or targets are not known.
Comparison with standard Dravet treatments
First-line therapies for Dravet syndrome are valproate and clobazam, often combined. Stiripentol (added to valproate + clobazam) and fenfluramine are also approved Dravet-specific agents [1].
In the absence of head-to-head randomized trials, indirect comparisons suggest fenfluramine may produce larger median reductions in convulsive seizure frequency than CBD. However, fenfluramine carries different risks (appetite suppression, weight loss, cardiac function monitoring) and is not appropriate for all patients [10]. Both drugs are typically added to baseline therapy, not replacements.
Sodium-channel blockers (carbamazepine, lamotrigine, phenytoin) can paradoxically worsen seizures in Dravet and are generally avoided [1].
CBD's practical advantages are a relatively favorable acute side-effect profile, lack of intoxication, and ease of administration (oral liquid or capsule). Key disadvantages are significant drug interactions (especially with clobazam and valproate), monitoring requirements, cost, and variable long-term efficacy.
Risk-benefit decisions about whether to use CBD, fenfluramine, stiripentol, or combinations of these belong with the treating neurologist.
Risks and side effects
Common adverse events in CBD trials for Dravet [2][3][5]:
- Somnolence and sedation (30–50% of patients), often worse when combined with clobazam
- Decreased appetite (15–30%)
- Diarrhea (10–20%)
- Elevated liver transaminases, particularly when co-administered with valproate (5–10% of patients develop mild to moderate elevation). Liver function monitoring (ALT, AST, bilirubin) is recommended at baseline, 1 month, 3 months, and regularly thereafter.
- Behavioral or mood changes (irritability, aggression in some reports)
Serious adverse events: Roughly 16–25% of CBD-treated patients in trials experienced serious adverse events, often defined broadly to include status epilepticus, infections, or transaminase elevations >3× upper limit of normal [2][3]. Rates of withdrawal due to adverse events were higher on CBD than placebo.
Drug interactions: CBD is a moderate inhibitor of CYP2C19 and CYP3A4, raising plasma levels of clobazam (especially its active metabolite N-desmethylclobazam), valproate, and other drugs metabolized by these enzymes [9]. This can increase both efficacy and toxicity. Dose adjustment of co-medications may be necessary.
Risk from non-pharmaceutical products: Dispensary CBD oils carry additional risks—inaccurate labeling, pesticide or solvent residues, and unintended THC exposure in pediatric patients [8].
Withdrawal: Abrupt discontinuation of CBD after prolonged use has not been well studied. Tapering is prudent, though seizure rebound (worsening) is possible.
How to use this information
This article is not medical advice. Dravet syndrome is a serious, life-threatening epilepsy. Do not start, stop, adjust, or change any antiseizure medication—including pharmaceutical CBD—without direct, ongoing supervision by a qualified pediatric neurologist or epileptologist.
If you are a caregiver considering CBD for a child with Dravet:
- Work with your specialist. Pharmaceutical CBD (Epidiolex) is approved and has trial evidence. Ask specifically about this, not generic "CBD oil" from a dispensary.
- Understand drug interactions. CBD interacts with clobazam, valproate, and other common Dravet drugs. Your doctor will need to monitor and possibly adjust doses.
- Plan for monitoring. Liver function tests, seizure diaries, and clinical reassessment are part of responsible use.
- Do not substitute with dispensary products. Over-the-counter CBD oils are not standardized, not proven equivalent, and may contain THC or contaminants.
- Know that seizure reduction is not seizure freedom. CBD typically cuts seizure frequency roughly in half in responders—substantial progress, but not a cure.
For more on drug interactions between cannabis and other medications, see Cannabis and Polypharmacy Risks.
For information on other cannabinoid treatments for epilepsy, see CBD and Lennox-Gastaut Syndrome.
Sources
- Peer-reviewed Wirrell EC, Hood V, Knupp KG, et al. International consensus on diagnosis and management of Dravet syndrome. Epilepsia. 2022;63(7):1761–1777.
- Peer-reviewed Devinsky O, Cross JH, Laux L, et al. Trial of Cannabidiol for Drug-Resistant Seizures in the Dravet Syndrome. New England Journal of Medicine. 2017;376(21):2011–2020.
- Peer-reviewed Miller I, Scheffer IE, Gunning B, et al. Dose-Ranging Effect of Adjunctive Oral Cannabidiol vs Placebo on Convulsive Seizure Frequency in Dravet Syndrome: A Randomized Clinical Trial. JAMA Neurology. 2020;77(5):613–621.
- Government U.S. Food and Drug Administration. FDA approves first drug comprised of an active ingredient derived from marijuana to treat rare, severe forms of epilepsy. Press release, June 25, 2018.
- Peer-reviewed Devinsky O, Nabbout R, Miller I, et al. Long-term cannabidiol treatment in patients with Dravet syndrome: An open-label extension trial. Epilepsia. 2019;60(2):294–302.
- Peer-reviewed Press CA, Knupp KG, Chapman KE. Parental reporting of response to oral cannabis extracts for treatment of refractory epilepsy. Epilepsy & Behavior. 2015;45:49–52.
- Peer-reviewed Porter BE, Jacobson C. Report of a parent survey of cannabidiol-enriched cannabis use in pediatric treatment-resistant epilepsy. Epilepsy & Behavior. 2013;29(3):574–577.
- Peer-reviewed Bonn-Miller MO, Loflin MJE, Thomas BF, et al. Labeling Accuracy of Cannabidiol Extracts Sold Online. JAMA. 2017;318(17):1708–1709.
- Peer-reviewed Geffrey AL, Pollack SF, Bruno PL, Thiele EA. Drug-drug interaction between clobazam and cannabidiol in children with refractory epilepsy. Epilepsia. 2015;56(8):1246–1251.
- Peer-reviewed Lagae L, Sullivan J, Knupp K, et al. Fenfluramine hydrochloride for the treatment of seizures in Dravet syndrome: a randomised, double-blind, placebo-controlled trial. Lancet. 2019;394(10216):2243–2254.
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