What happens when you take cbd with valproate?
Valproate (valproic acid, divalproex sodium) is a broad-spectrum anti-seizure medication also used for migraine prophylaxis and bipolar disorder. It is well known to cause dose-dependent liver enzyme elevation, rare idiosyncratic hepatotoxicity, hyperammonemia (sometimes with encephalopathy even when liver enzymes are normal), and pancreatitis. Cannabidiol (CBD, Epidiolex) carries its own hepatotoxicity signal: in clinical trials, dose-dependent transaminase elevations were observed, and the FDA label includes a Warnings and Precautions section on hepatocellular injury.
When the two are used together, the rates of clinically meaningful ALT/AST elevation rise sharply compared to either drug alone. In pooled controlled trial data summarized in the Epidiolex prescribing information, ALT elevations greater than 3x the upper limit of normal occurred in approximately 17% of patients on the CBD plus valproate combination, compared to roughly 1-2% of patients on valproate without CBD and a lower rate on CBD without valproate. The relationship is dose-dependent: 8% at CBD 10 mg/kg/day versus 16% at 20 mg/kg/day in pooled analyses. The mechanism is not fully resolved but likely involves overlapping hepatic stress and possibly metabolic interactions among CBD, valproate, and shared cofactors. Postmarketing reports have also described elevated ammonia levels in Epidiolex-treated patients, frequently in the setting of concomitant valproate, clobazam, or both.
Why is this important?
Many patients on valproate have refractory epilepsy and are exactly the population for whom CBD (and pharmaceutical Epidiolex) is being considered - Lennox-Gastaut syndrome, Dravet syndrome, tuberous sclerosis complex. The combination is therefore common and predictable, not exotic. Most transaminase elevations are asymptomatic and reversible with dose reduction or discontinuation, but a minority progress and a small number can become serious. Hyperammonemic encephalopathy can occur even with relatively modest liver enzyme changes and presents as new confusion, lethargy, or unexplained worsening of seizure control, which can be misattributed to disease progression.
The risk also extends to over-the-counter CBD products. Many parents and adult patients on valproate use consumer CBD oils for breakthrough symptoms without telling the neurologist, on the assumption that 'natural' hemp products are not real drugs. The hepatotoxicity signal is dose-dependent and consumer products at modest doses are likely lower risk than 20 mg/kg/day Epidiolex, but they are not zero risk, and the combination warrants laboratory monitoring regardless of source.
What should you do?
This combination should be managed by the prescribing neurologist with structured laboratory monitoring.
- Tell the prescriber about all CBD use - pharmaceutical and over-the-counter - before starting valproate, and before adding CBD if already on valproate.
- Get baseline liver enzymes (ALT, AST, alkaline phosphatase, total bilirubin) before starting either drug, and again at 1, 3, and 6 months after initiation or any dose increase, per the Epidiolex label's general hepatotoxicity monitoring recommendations.
- Check ammonia if there are new symptoms of lethargy, confusion, worsening seizures, or unexplained vomiting - hyperammonemic encephalopathy can present without dramatic liver enzyme changes.
- If ALT or AST rises above 3x the upper limit of normal, or if symptoms of hepatic injury appear (jaundice, dark urine, right upper quadrant pain, fatigue, anorexia, nausea), contact the prescriber immediately. The Epidiolex label provides specific guidance on dose reduction or discontinuation thresholds.
- Avoid additional hepatic stressors: alcohol, high-dose acetaminophen, anabolic steroids, kava, comfrey, chaparral, and unregulated bodybuilding supplements.
- Be cautious with concomitant clobazam, which appears to add further to the hyperammonemia signal.
Which specific products are affected?
Valproate is sold as Depakote, Depakote ER, Depakene, Depacon (injectable), Stavzor, Epilim, and many generics; the divalproex, valproic acid, and valproate sodium forms behave the same way for this interaction. The CBD interaction is best characterized for pharmaceutical Epidiolex (cannabidiol oral solution) at anti-seizure doses, but consumer CBD products - tinctures, gummies, capsules, vapes - contain the same active molecule and share the mechanism. Full-spectrum hemp products that include THC add their own hepatic-metabolism load. Clobazam in addition to CBD plus valproate appears to compound the hyperammonemia risk, so triple therapy demands particularly close monitoring.
The bottom line
Combining CBD with valproate produces a clinically significant, dose-dependent increase in ALT/AST elevations and a documented signal for hyperammonemia, well above the rates seen with either drug alone. The FDA Epidiolex label addresses this directly, and the combination is manageable with prescriber oversight and scheduled liver function testing. Do not add any CBD product - prescription or over-the-counter - to valproate without involving the neurologist and arranging baseline and follow-up labs.