Cannabis for Epilepsy in Australia — CBD, Epidyolex & What the Evidence Shows (2026)

Epilepsy affects approximately 250,000 Australians — around one in every 100 people. While seizures can often be controlled with conventional anti-seizure medications (ASMs), up to 30% of people with epilepsy have treatment-resistant epilepsy (TRE) — defined as failure to achieve sustained seizure freedom with two or more appropriately chosen and adequately dosed ASMs. For these patients, and particularly for children with rare, severe epilepsy syndromes, the search for effective alternatives has driven intense interest in medicinal cannabis.

Of all the medical applications of cannabis, epilepsy — specifically CBD for rare childhood epilepsy syndromes — has the most rigorous evidence base and the only TGA-registered cannabis medicine: Epidyolex (pharmaceutical-grade purified CBD oral solution).

This guide explains what the evidence shows, who is most likely to benefit, how Epidyolex differs from other CBD products, and how to access treatment in Australia.

The evidence: CBD and seizure reduction

The pivotal trials that established CBD as a seizure treatment were conducted in children with two rare, severe epilepsy syndromes:

Dravet syndrome

Dravet syndrome is a severe, genetic epilepsy beginning in the first year of life and characterised by frequent, prolonged seizures — particularly febrile seizures — that are notoriously difficult to control with conventional ASMs. Cognitive development is frequently affected.

The landmark 2017 Devinsky et al. trial in the New England Journal of Medicine randomly assigned 120 children and young adults with Dravet syndrome to receive CBD (Epidyolex) or placebo in addition to their existing ASMs. The CBD group experienced a median reduction in convulsive seizures of 38.9%, compared to 13.3% in the placebo group. Seizure freedom was achieved in 5% of the CBD group versus 0% in placebo. A subsequent trial confirmed these findings.

Lennox-Gastaut syndrome (LGS)

LGS is a severe childhood-onset epilepsy characterised by multiple seizure types, intellectual disability and a characteristic EEG pattern. Two Phase 3 RCTs of Epidyolex in LGS found median reductions in drop seizures (the most disabling seizure type in LGS) of 41–44% with CBD, compared to 17–22% with placebo.

Other epilepsies

Evidence for CBD in epilepsy types beyond Dravet and LGS is more limited but increasingly positive:

• Tuberous sclerosis complex (TSC): A Phase 3 trial found CBD reduced seizure frequency by 48% versus 26% placebo reduction
• Treatment-resistant adult epilepsies: Several observational studies and open-label trials show meaningful seizure reduction in adult TRE with CBD
• CDKL5 deficiency disorder (CDD) and Angelman syndrome: Observational data is encouraging but RCTs are limited

For broader epilepsy types (beyond Dravet and LGS), CBD is not TGA-registered and is prescribed off-label under the SAS-B framework — meaning a neurologist uses their clinical judgment supported by emerging evidence.

Epidyolex vs other CBD products: why it matters

Epidyolex is pharmaceutical-grade purified CBD — the same compound present in full-spectrum cannabis but isolated, standardised and rigorously tested. Understanding how it differs from other CBD products available in Australia is essential.

	Epidyolex	Pharmaceutical CBD oils (SAS-B)	OTC CBD (pharmacy, up to 150mg/day)
CBD purity	>98% pure CBD	Variable (typically 95%+)	Variable
THC content	<0.1%	<0.3% (legal limit)	<0.3%
Dose precision	High — defined mg/mL	Good	Moderate
TGA status	Registered medicine	SAS-B (unapproved)	Schedule 3
Clinical trial data	Extensive (Dravet, LGS)	Limited	Very limited
Cost	High	Moderate	Low
Paediatric use	Specifically studied and dosed	Off-label	Not recommended

For Dravet syndrome and LGS in children, Epidyolex is the recommended first-choice cannabis medicine — the evidence base, dose precision and purity make it the appropriate product. For adult TRE or other epilepsy types, pharmaceutical CBD oils under SAS-B may be more cost-effective while offering similar benefit.

OTC CBD products available at pharmacies without a prescription are not appropriate for epilepsy treatment. The doses studied in epilepsy trials (starting at 2.5mg/kg/day, titrated to 10–20mg/kg/day) far exceed what OTC products provide, and the lack of consistent quality and dosing in OTC products creates unacceptable variability in a seizure management context.

What about THC?

For epilepsy, CBD is the cannabinoid of interest — not THC. THC may actually lower the seizure threshold at higher doses and has inconsistent effects on seizure frequency. For children with epilepsy, THC is generally contraindicated.

This is a fundamentally different situation from most other medicinal cannabis applications, where a balanced THC:CBD or THC-dominant product is often preferable. For epilepsy: CBD, not THC.

Some patients with adult TRE who use cannabis recreationally report anecdotal seizure reduction with THC-containing products. There is no robust clinical evidence to support intentional use of THC for seizure control, and the risk-benefit ratio is unfavourable given what we know about CBD’s efficacy.

Dosing CBD for epilepsy

Dosing for epilepsy is more structured than for most medicinal cannabis applications, and should always be managed by a neurologist, not a general practitioner alone.

Epidyolex starting protocol (Dravet and LGS):

• Starting dose: 2.5mg/kg/day, split into two doses
• Increase by 2.5mg/kg increments every 7 days as tolerated
• Target maintenance dose: 10mg/kg/day (most patients)
• Maximum studied dose: 20mg/kg/day

Adult TRE (pharmaceutical CBD oil under SAS-B):

• Starting dose: 5mg/kg/day or 150–300mg/day (whichever is lower)
• Titrate weekly as tolerated under neurologist supervision
• Typical effective doses in adult TRE observational studies: 200–600mg/day

Timing: CBD for epilepsy is taken twice daily (morning and evening) at consistent times. Consistent dosing times help maintain stable plasma levels, which correlates with better seizure control.

Drug interactions: CBD and anti-seizure medications

This is the most clinically critical aspect of using CBD for epilepsy. CBD is a potent inhibitor of CYP2C19 and has clinically meaningful interactions with several commonly prescribed ASMs.

Anti-seizure medication	Interaction with CBD	Clinical significance
Clobazam (Frisium)	CBD inhibits CYP2C19, raising N-desmethylclobazam levels 3–5x	Increased sedation, may require dose reduction — monitor closely
Valproate (Epilim)	Additive hepatotoxicity risk	Liver enzymes should be monitored closely, especially in children
Stiripentol	Additive effect; used intentionally in some Dravet protocols	Managed under specialist supervision
Phenytoin, carbamazepine	May affect CBD metabolism	Monitor plasma levels
Topiramate, levetiracetam	Minimal interaction	Generally safe to combine

The clobazam interaction is particularly important in Dravet syndrome, where clobazam is commonly prescribed. The metabolite elevation can cause additional sedation at previously well-tolerated clobazam doses — neurologists typically reduce clobazam when adding CBD. This interaction is also associated with some of the therapeutic benefit, as raised N-desmethylclobazam contributes to seizure control.

Bottom line: CBD for epilepsy requires neurologist oversight, regular blood tests (liver function and, where appropriate, ASM plasma levels), and careful titration. It is not appropriate to self-manage epilepsy cannabis treatment.

Accessing medicinal cannabis for epilepsy in Australia

For children with Dravet syndrome or Lennox-Gastaut syndrome

Epidyolex requires a prescription from a paediatric neurologist and is a registered TGA medicine — meaning it does not require the same SAS-B approval process as other medicinal cannabis products. Your child’s neurologist can prescribe directly.

Epidyolex is also listed on the PBS for Dravet syndrome and LGS in patients aged 2 years and over who meet specific criteria — this is a major development that significantly reduces cost for eligible families. Ask your neurologist to check PBS eligibility (PBS item 11374X and related items).

For adult TRE or other epilepsies

CBD under the SAS-B framework can be prescribed by a neurologist or, in some circumstances, a GP with specialist input. Most neurologists recommend a formal trial with documentation of seizure diaries before and during treatment to assess response objectively.

Step 1: Ask your neurologist specifically about CBD at your next appointment. Bring a 4-week seizure diary showing baseline frequency.

Step 2: If your neurologist is not familiar with SAS-B prescribing, ask for a referral to a neurologist experienced in medicinal cannabis — many epilepsy centres in major Australian cities now have this expertise.

Step 3: Begin a structured trial with defined seizure outcome measures. A 12-week trial with consistent dosing is typically sufficient to assess response.

Cost

• Epidyolex via PBS (Dravet/LGS): PBS-subsidised — concession holders pay the standard concession co-payment; general patients pay the standard patient contribution (around $30–50). This is a significant cost reduction from the pre-PBS price.
• Epidyolex without PBS subsidy: Very expensive — $1,000+ per month at clinical doses. Contact the manufacturer (Jazz Pharmaceuticals) about compassionate access programs.
• CBD oil under SAS-B: $150–400/month at typical adult doses.

What to realistically expect

CBD does not eliminate seizures in most patients but can meaningfully reduce their frequency. In Dravet and LGS trials, approximately:

• 40–50% of patients achieve a 50% or greater reduction in seizure frequency (“50% responder” rate)
• 5–10% achieve seizure freedom
• 10–20% do not respond meaningfully

In adult TRE observational studies, responder rates are somewhat lower (30–40%), but even a 30–50% seizure reduction can translate to major quality of life improvements.

CBD does not cure the underlying epilepsy. If it is stopped, seizures typically return to baseline frequency. Sudden discontinuation should be avoided — taper over weeks under neurologist guidance.

Frequently asked questions

Is cannabis legal for epilepsy in Australia? Yes, with a prescription. Epidyolex (pharmaceutical CBD) is a TGA-registered medicine for Dravet syndrome and LGS and is available via normal prescription. CBD for other epilepsy types is available under the TGA’s SAS-B framework. THC-containing cannabis is generally not appropriate for epilepsy.

Is Epidyolex covered by the PBS in Australia? Yes — Epidyolex is PBS-listed for patients aged 2 years and over with Dravet syndrome or Lennox-Gastaut syndrome. PBS subsidy significantly reduces cost for eligible patients. Ask your neurologist about eligibility criteria (PBS items 11374X, 11375Y, 11376K).

Can adults use cannabis for epilepsy? Yes, though the strongest evidence is in childhood epilepsy syndromes. Adults with treatment-resistant epilepsy can access CBD under the TGA’s SAS-B framework. Neurologist oversight is essential. Several Australian epilepsy centres now have dedicated medicinal cannabis clinics.

Can CBD interact with my epilepsy medications? Yes — significantly. CBD raises blood levels of clobazam metabolites (via CYP2C19 inhibition) and has additive liver toxicity risk with valproate. Neurologist management, regular blood tests and careful titration are essential. Do not add CBD to epilepsy medications without specialist guidance.

Will cannabis affect my child’s development? At the doses used for epilepsy (CBD only, no THC), available evidence does not indicate significant adverse developmental effects. In fact, reducing seizure burden — which CBD achieves — generally benefits developmental outcomes in children with Dravet and LGS. This is distinct from THC exposure in developing brains, which carries well-documented developmental risks and is contraindicated in children.

What if CBD doesn’t control my seizures? Non-response does not mean every avenue has been tried — dose, product and timing all affect response. Discuss dose escalation and alternative CBD formulations with your neurologist. If CBD is ineffective after a structured trial at adequate doses, your neurologist can advise on other treatment-resistant epilepsy options including dietary therapies (ketogenic diet), neuromodulation (VNS, RNS) and surgery candidacy evaluation.

Can I drive if I’m taking CBD for epilepsy? Driving eligibility for people with epilepsy in Australia is governed by strict state-based regulations based primarily on seizure-free period — these rules are separate from cannabis-specific driving laws. CBD-only products do not impair driving. If seizures are not fully controlled, standard epilepsy driving restrictions apply regardless of cannabis use. Discuss driving eligibility with your neurologist.