• Lennox-Gastaut syndrome, Dravet syndrome, tuberous sclerosis complex: Strong. Prescription CBD (Epidiolex) is FDA-approved. In Lennox-Gastaut, drop seizures fell by a median of 44% versus 22% on placebo, and 44% of patients had their seizures cut by half or more. In Dravet, seizures fell 39% versus 13%.

• Other epilepsies and dispensary products: Not established. Dispensary CBD differs in dose and purity from Epidiolex.

Good to know: CBD raises levels of clobazam and can affect the liver with valproate. Blood tests are needed. Never change seizure medicines without your neurologist.

What to ask for: Prescription Epidiolex through your neurologist. Dispensary products should be discussed with your neurologist first. Avoid THC-dominant products unless your neurologist advises otherwise.