Prescription CBD for epilepsy starts at 2.5 mg per kilogram of body weight twice daily, which works out to 5 mg/kg per day. Doctors then raise the dose in planned steps, often to 5 mg/kg twice daily, and up to 10 mg/kg twice daily for some seizure types. There is no single CBD oil dose that fits everyone, and over-the-counter CBD has no approved dosing schedule for epilepsy at all.
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What is the starting CBD dosage for epilepsy?
The starting dose of Epidiolex (the only FDA-approved CBD medicine for seizures) is 2.5 mg/kg twice daily for the first week. Weight drives the number, so a 20 kg child takes 50 mg per dose and 100 mg per day at the start. The dose climbs only when seizures continue and side effects stay manageable.
Daily CBD targets by seizure type
- Lennox-Gastaut syndrome: 10 mg/kg per day is the usual target, up to 20 mg/kg per day.
- Dravet syndrome: the same range, with 10 mg/kg per day as the goal and 20 mg/kg per day as the ceiling.
- Tuberous sclerosis complex: up to 25 mg/kg per day in clinical use.
These figures come from the Epidiolex label. A 30 kg patient at 10 mg/kg per day takes 300 mg per day, split into two 150 mg doses.
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How does a doctor adjust the CBD dose over time?
Titration means small increases spaced out over days or weeks. The goal is the lowest dose that cuts seizures without causing drowsiness, stomach upset, or liver problems.
- Week 1: 2.5 mg/kg twice daily (5 mg/kg per day).
- Week 2: increase to 5 mg/kg twice daily (10 mg/kg per day) if needed.
- Later weeks: further increases of 2.5 mg/kg twice daily, with no more than one increase per week, up to the maximum for the seizure type.
- Blood tests: liver enzymes checked before treatment starts, then at one month, three months, six months, and after any dose change.
Why is the dose written as mg/kg instead of mg?
Body weight changes how much CBD reaches the brain, so a fixed milligram amount would underdose a 70 kg adult or overdose a 15 kg child. Pediatric epilepsy trials used mg/kg, and the FDA label followed the same system. Adults with seizures from tuberous sclerosis or Lennox-Gastaut syndrome use the same mg/kg math as children.
Is over-the-counter CBD oil dosed the same way?
No. Store-bought CBD oil has no approved dose for epilepsy, no required purity testing, and no standard strength. FDA lab tests have found products with THC, with less CBD than the label claims, or with no CBD at all. Some people use OTC CBD for seizures, but any dose they pick is a guess.
Does CBD oil replace seizure medication?
CBD is added to existing anti-seizure drugs, not swapped in for them. Stopping or lowering a prescription seizure medicine on your own can trigger withdrawal seizures or status epilepticus. Every change belongs with your neurologist.
What side effects and interactions matter?
CBD for epilepsy carries real risks, even at low doses. The FDA label lists sleepiness, fatigue, diarrhea, vomiting, appetite loss, and liver injury.
- Liver: CBD can raise liver enzymes. Signs of damage include yellow eyes, dark urine, and pain on the right side of the belly.
- Clobazam: CBD raises levels of its active metabolite, which adds to sedation.
- Valproate: combined use raises the odds of liver problems and low platelets.
- Warfarin and other drugs: CBD can shift blood levels through liver enzymes CYP2C19 and CYP3A4.
What should you check before using CBD oil for seizures?
- Ask the neurologist first, and flag clobazam, valproate, or a blood thinner.
- Request a certificate of analysis from an outside lab for any CBD product.
- Check the THC content. THC can trigger seizures in some people and adds intoxication.
- Keep a seizure diary with dates, dose, and side effects so dose changes rest on data.
Frequently asked questions
Can I start at a high CBD dose to stop seizures faster?
No. High starting doses raise the risk of liver injury, sedation, and drug interactions without speeding up seizure control. The label calls for a low start and slow increases for that reason.
How long does CBD take to work for epilepsy?
Some families see fewer seizures within the first month, and trial results show the largest drop after about 12 to 14 weeks of stable dosing. If nothing changes by three months at a proper dose, the treatment is not working.
What is the maximum CBD dose for epilepsy?
For Epidiolex, the ceiling is 20 mg/kg per day for Lennox-Gastaut syndrome and Dravet syndrome, and 25 mg/kg per day for tuberous sclerosis complex. Higher doses are studied, but side effects rise with them.
Does full-spectrum CBD oil work better than pure CBD for seizures?
The seizure trials used purified CBD, not full-spectrum oil. There is no solid human evidence that plant terpenes or trace cannabinoids add seizure control, and THC may do the opposite.