Class landing · Antiepileptics

Supplements and antiepileptic drugs.

Phenytoin, carbamazepine, valproate, lamotrigine and the CYP-substrate supplements that disrupt seizure control.

Older antiepileptic drugs (phenytoin, carbamazepine, valproate) are strong inducers or inhibitors of CYP enzymes. Newer ones (lamotrigine, levetiracetam) less so. Supplements that share those CYP substrates can shift blood levels in either direction, with seizure-control implications.

The headline exclusion is St John’s Wort: CYP3A4 induction reduces blood levels of most antiepileptics and can break seizure control. Folate is the other side of the same coin: long-term valproate depletes folate, which is associated with elevated homocysteine and (in pregnancy) neural tube defect risk; supplementation is standard. Vitamin D and calcium are flagged on long-term antiepileptic use for bone health (enzyme-inducing AEDs increase vitamin D clearance).

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For adults over 18. This tool gives evidence-graded information, not medical advice. Always discuss changes with your GP, especially if you take any medication, are pregnant, breastfeeding, or have a serious health condition.

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Distil's interactions database is reviewed and updated every quarter. We grade evidence transparently and publish our methodology, including every database change, at /about/methodology. This tool is information, not a substitute for clinical judgement. If you take medication and supplements together, your GP or pharmacist can review your full regimen against your medical history. If you want a full personalised stack reasoned against this same database, the Distil report is the next step up.