Last verified: April 2026

Charlotte Figi — The Case That Changed Everything

The modern CBD-epilepsy story begins with Charlotte Figi, a Colorado girl diagnosed with Dravet syndrome — a severe, treatment-resistant genetic epilepsy caused by mutations in the SCN1A sodium channel gene. By age 5, Charlotte was experiencing approximately 300 seizures per week despite maximum conventional therapy, including seven anticonvulsants, a ketogenic diet, and vagus nerve stimulation. Her parents were told there were no remaining treatment options.

In desperation, Charlotte’s mother Paige Figi contacted the Stanley Brothers — cannabis cultivators in Colorado who had bred a high-CBD, low-THC strain they could not sell because recreational consumers found it undesirable. They had nicknamed it “Hippie’s Disappointment.” Charlotte began treatment with a 30:1 CBD:THC oil extract, and her seizure frequency dropped from 300 per week to 2–3 per month — a reduction of over 99%.

The strain was renamed “Charlotte’s Web” in her honor. The story reached national awareness through Dr. Sanjay Gupta’s CNN documentary “Weed,” which aired in August 2013. Gupta — CNN’s chief medical correspondent, who had previously written an op-ed opposing medical cannabis — publicly reversed his position after meeting Charlotte and reviewing the evidence, stating that the medical community had been “systematically misled.”

The documentary triggered three transformative consequences. Families of children with intractable epilepsy began relocating to Colorado to access Charlotte’s Web, becoming known as “cannabis refugees.” Conservative states that had no medical cannabis programs passed CBD-specific laws (sometimes called “Charlotte’s Web laws”), creating a new legal category for non-psychoactive cannabinoids. And the research community, galvanized by both the clinical observation and the public demand, accelerated the clinical trial pipeline that would ultimately produce Epidiolex.

Charlotte Figi died on April 7, 2020, at age 13, from complications associated with COVID-19. Her family noted that her health had always been fragile due to her underlying condition. Her legacy extends far beyond one patient — she fundamentally altered the trajectory of cannabinoid medicine and federal cannabis policy.

Epidiolex Pivotal Trials — The Clinical Evidence

The transition from anecdotal case report to FDA approval was driven by GW Pharmaceuticals (now Jazz Pharmaceuticals), which developed Epidiolex — a purified, pharmaceutical-grade cannabidiol oral solution — and conducted the large-scale randomized controlled trials required for regulatory approval.

Dravet Syndrome (Devinsky et al., 2017): The pivotal trial, led by Orrin Devinsky at NYU Langone and published in the New England Journal of Medicine, enrolled 120 children and young adults with Dravet syndrome. Patients received CBD at 20 mg/kg/day or placebo for 14 weeks. The results were unambiguous:

• Median monthly convulsive seizure frequency dropped from 12.4 to 5.9 in the CBD group (a 38.9% reduction from baseline)
• The placebo group showed a reduction from 14.9 to 14.1 (a 13.3% reduction)
• The between-group difference was statistically significant (p = 0.01)
• 5% of CBD patients became completely seizure-free during the treatment period, compared to 0% in placebo
• 43% of CBD patients achieved ≥50% seizure reduction, compared to 27% in placebo

Cannabidiol resulted in a greater reduction in convulsive-seizure frequency than placebo among children and young adults with Dravet syndrome.

Devinsky et al., New England Journal of Medicine 2017

Lennox-Gastaut Syndrome (LGS): Two additional pivotal trials tested CBD in LGS, another severe childhood-onset epilepsy characterized by multiple seizure types and cognitive impairment. Both trials demonstrated statistically significant reductions in monthly drop seizure frequency: 37–42% reduction in the CBD groups compared to 17% in placebo. Both the 10 mg/kg/day and 20 mg/kg/day doses were effective, with the higher dose producing greater efficacy but also more adverse effects — a standard dose-response tradeoff.

Tuberous Sclerosis Complex (TSC): In 2020, Epidiolex received a supplemental FDA approval for seizures associated with TSC, based on a Phase 3 trial demonstrating significant seizure reduction. This expanded the approved indications from two to three rare epilepsy syndromes, further solidifying CBD’s position as a legitimate anticonvulsant.

Epidiolex received initial FDA approval on June 25, 2018, making it the first plant-derived cannabinoid drug approved by the FDA. It was originally placed in Schedule V (the least restrictive controlled substance category), then descheduled entirely in April 2020 — the first descheduled cannabis-derived prescription drug in U.S. history.

Mechanism of Action — Why CBD Stops Seizures

Unlike most anticonvulsants, which operate through a single primary mechanism, CBD’s antiepileptic activity appears to involve multiple convergent pathways, none of which depend on the CB1 or CB2 receptors classically associated with cannabis pharmacology:

GPR55 Antagonism: CBD blocks the orphan receptor GPR55, which functions as an excitatory signal in the brain. GPR55 activation increases intracellular calcium release and enhances glutamatergic (excitatory) neurotransmission. By antagonizing GPR55, CBD reduces neuronal excitability at a fundamental level. This mechanism was identified by Kaplan et al. and has been demonstrated in multiple seizure models.

TRPV1 Desensitization: CBD activates and subsequently desensitizes the transient receptor potential vanilloid 1 (TRPV1) channel. Initial TRPV1 activation opens a cation channel, but sustained exposure by CBD causes the channel to become refractory — effectively silencing a source of neuronal excitation. TRPV1 is expressed on hippocampal neurons and has been implicated in temporal lobe epilepsy, making this mechanism anatomically relevant.

Adenosine Reuptake Inhibition: CBD inhibits the equilibrative nucleoside transporter 1 (ENT1), blocking the reuptake of adenosine from the extracellular space. Adenosine is a potent endogenous anticonvulsant — it is, in fact, the brain’s primary seizure-termination mechanism. By increasing extracellular adenosine concentrations, CBD augments the brain’s own anticonvulsant signaling. This mechanism also contributes to CBD’s anti-inflammatory effects, as adenosine activates A1 and A2A receptors on immune cells.

Sodium Channel Modulation: CBD modulates voltage-gated sodium channels (Nav1.1–Nav1.7), reducing the rapid inward sodium current that initiates action potentials in hyperexcitable neurons. This mechanism is shared with established anticonvulsants like carbamazepine and phenytoin, providing a conventional pharmacological basis alongside the more novel receptor targets. Notably, Dravet syndrome is caused by mutations in SCN1A (which encodes Nav1.1), making sodium channel modulation particularly relevant to the very condition where CBD has the strongest clinical evidence.

The convergence of these mechanisms — reducing excitation through GPR55 and TRPV1, enhancing endogenous seizure suppression through adenosine, and stabilizing sodium channels — may explain why CBD is effective in treatment-resistant epilepsies that have failed multiple conventional anticonvulsants targeting individual pathways.

Safety and Adverse Effects

Epidiolex trials identified several clinically significant adverse effects. Somnolence affected approximately 25% of CBD patients (vs. 10% placebo) and was the most common dose-limiting side effect. Diarrhea occurred in 20–30% of patients. Decreased appetite and fatigue were reported at rates significantly above placebo.

The most serious safety signal was hepatotoxicity. In patients concurrently taking valproate (valproic acid), 21% developed elevated ALT levels exceeding three times the upper limit of normal. In patients not taking valproate, the rate was 3%. This interaction is mediated by CBD’s potent inhibition of CYP2C19 and CYP3A4, which are involved in valproate metabolism. The Epidiolex label includes a Hepatocellular Injury warning and requires baseline and periodic liver function monitoring.

CBD also increases clobazam levels by approximately 3-fold through CYP2C19 inhibition. Since clobazam is frequently co-prescribed in epilepsy, this interaction has practical significance: some of the observed sedation and efficacy may be partially attributable to increased clobazam exposure rather than direct CBD anticonvulsant activity. Distinguishing direct CBD effects from pharmacokinetic interactions with concomitant medications remains an active area of research.

Beyond Epidiolex — The Broader Epilepsy Question

Epidiolex’s approval is specific to three rare epilepsy syndromes. Whether CBD is effective for the more common epilepsies — temporal lobe epilepsy, absence epilepsy, juvenile myoclonic epilepsy — remains unproven by controlled trial data. Observational studies and open-label extensions suggest that some patients with other epilepsy types respond, but the magnitude and reliability of the response in broader populations is unknown.

The question of whole-plant extracts versus purified CBD is scientifically unresolved but commercially contentious. Charlotte Figi responded to a whole-plant extract containing trace THC and other cannabinoids, not purified CBD. Some researchers, including Aran et al. (2021), have reported that whole-plant extracts containing a 20:1 CBD:THC ratio may produce outcomes that purified CBD does not — a finding consistent with the entourage effect hypothesis but requiring replication. Epidiolex is purified CBD precisely because regulatory approval requires a defined, reproducible pharmaceutical composition — the question of whether something is lost in purification remains open.

The epilepsy story demonstrates what is possible when cannabinoid research follows the standard clinical development pathway: preclinical mechanistic work, dose-finding studies, pivotal Phase 3 trials, regulatory review, and post-marketing surveillance. It is the model that every other therapeutic claim — pain, anxiety, PTSD, cancer — must be measured against.