Medical Cannabis for Epilepsy: CBD Evidence and Doses
CBD is the only cannabis compound with FDA approval for epilepsy. Epidiolex treats Dravet, Lennox-Gastaut, and tuberous sclerosis. THC has no approval.
What the evidence covers
Clinical data on cannabis and epilepsy comes from purified cannabidiol, not dried flower. GW Pharmaceuticals ran four randomized trials on Epidiolex, a plant-derived CBD oral solution. The FDA approved it in June 2018 for Dravet syndrome and Lennox-Gastaut syndrome, then in 2020 for tuberous sclerosis complex. Trial doses ran 10 mg/kg/day to 20 mg/kg/day. In the 2017 Dravet trial, median monthly convulsive seizures fell from 12.4 to 5.9 on CBD against 14.9 to 14.1 on placebo. In the 2018 Lennox-Gastaut trial, the 20 mg/kg dose cut seizures 43.9% versus 21.8% for placebo.
Medical Cannabis for Epilepsy: CBD Evidence and Doses
No randomized trial has tested smoked or vaporized flower against placebo for epilepsy. Strain reviews and patient surveys rank lower on the evidence scale. Treat strain picks as a topic for a neurologist visit, not a treatment plan.
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Top pick: Charlotte's Web
Charlotte's Web tests near 17% CBD and under 0.3% THC. It is the strain tied to the 2013 reporting on Charlotte Figi, a Colorado child with Dravet syndrome. Family accounts put her seizures at about 300 per week before the extract and under 10 per week after. That number comes from press reports, not a controlled trial.
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Why it ranks first
- THC stays under the 0.3% federal hemp limit, which fits states that cap THC in medical products.
- Supply is the widest of any high-CBD name. Flower, oil, and capsule forms exist.
- Batch lab data is public from several producers.
Other options, ranked
2. Harle-Tsu
CBD to THC ratio near 20:1. CBD tests 18% to 22%, THC under 1%. A cross of Harlequin and Sour Tsunami. Mild sedative effect. Good for evening dosing.
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3. ACDC
CBD to THC ratio near 20:1. CBD tests 15% to 19%. Low THC, so it suits patients who react to THC with anxiety or racing heart. Reports describe clear-headed effects.
4. Ringo's Gift
CBD tests 15% to 20%, THC under 1%. Bred in California. Terpene profile leans toward myrcene and pinene. Sold as flower and as CBD-rich extract.
5. Cannatonic
CBD to THC ratio near 1:1 to 2:1. CBD tests 6% to 17%. The THC content makes this a poor first choice for seizure patients. Some users report THC triggers seizures. Animal studies show THC can lower seizure threshold. Case reports tie high-THC products to seizure onset in a small number of patients.
What to check on a label
- Batch-specific certificate of analysis. Look for cannabinoid, pesticide, heavy metal, and mold panels.
- CBD percentage by weight, not total milligrams per package.
- THC percentage. Under 1% keeps psychoactive effects low.
- Harvest date. Cannabinoids degrade with heat and light.
Limits of these picks
Strain names are not standardized. Two growers can sell "ACDC" with different cannabinoid numbers. The FDA has not approved flower or THC products for epilepsy. Epidiolex holds the only approval in this category. State medical cannabis programs list epilepsy as a qualifying condition in most legal states. Rules differ by state on possession limits, THC caps, and patient registration. Confirm status with a state health department and a neurologist before purchase.