How Does Medical Cannabis Help Epilepsy: A Buyer's Guide to CBD and THC Products
Learn how medical cannabis may reduce seizures and what to check before buying: CBD to THC ratios, lab tests, dosing, and pitfalls.
Answer
Medical cannabis for epilepsy means cannabidiol (CBD) in most cases. CBD is the only cannabis compound with U.S. Food and Drug Administration approval for seizures. The drug Epidiolex treats three conditions: Lennox-Gastaut syndrome, Dravet syndrome, and tuberous sclerosis complex. Approval covers patients age 2 and older. Pure THC has no FDA approval for epilepsy. No state medical cannabis program requires THC for seizure control.
What the evidence shows
Three randomized placebo-controlled trials led to Epidiolex approval. Median seizure frequency dropped 30% to 40% in treated groups. Results vary by epilepsy type. Dravet syndrome showed the largest response. A Cochrane review of these trials found CBD reduces seizure frequency when added to standard anticonvulsants. The review also noted side effects and study limits.
Dosing
Epidiolex dosing starts at 2.5 mg per kg of body weight twice daily. That equals 5 mg/kg/day. After one week, the dose rises to 5 mg/kg twice daily (10 mg/kg/day). The maximum is 10 mg/kg twice daily (20 mg/kg/day). A 30 kg child at the starting dose takes 75 mg twice daily. Doctors adjust the dose with liver enzyme tests and sedation checks.
medical cannabis vs traditional seizure meds
Side effects and interactions
- Liver enzyme increases. Risk rises with valproate.
- Sleepiness (somnolence).
- Diarrhea, vomiting, decreased appetite.
- Rash or fever in some patients.
CBD interacts with clobazam. It raises levels of the metabolite norclobazam, which adds sedation. CBD also affects CYP450 enzymes, so it changes levels of other drugs. Patients need blood tests at 1 month, 3 months, and 6 months after starting.
State medical cannabis programs
38 states plus DC allow medical cannabis for epilepsy. Qualifying conditions vary. Some states list seizures or epilepsy as a category. Others require a neurologist signature. Products sold in dispensaries contain CBD, THC, or both. Labels list CBD and THC levels in mg per dose in most states. Lab testing rules differ by state. No federal standard exists for dispensary products.
THC and seizures
THC evidence for epilepsy is thin. Some case reports describe seizure reduction with THC. Other reports describe seizure worsening. The American Epilepsy Society says no good evidence supports THC alone for seizures. Whole-plant cannabis trials are small and lack placebo controls in most cases.
What to ask a doctor
- Does my epilepsy type match FDA approval for CBD?
- Which current drugs interact with CBD?
- What liver tests are needed?
- Is a state medical cannabis card required?
Keep a seizure diary. Note dates, types, and lengths. Bring the diary to each visit.