NutriStack
Carbamazepine and St. John's Wort, a conflict.
Both carbamazepine and St. John's Wort are potent CYP3A4 inducers. Combining them creates unpredictable effects on drug metabolism, potentially causing auto-induction of carbamazepine's own metabolism, leading to subtherapeutic anticonvulsant levels and increased seizure risk.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
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What the row says.
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At a glance
- Substances
- Carbamazepine and St. John's Wort
- Pair type
- Conflict
- Evidence (highest tier)
- Moderate
- Source citations
- 1 source
- Stack Score effect
- −10 to your Stack Score (per scored conflict row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Conflict · Moderate evidence
Conflict
What is happening. Both carbamazepine and St. John's Wort are potent CYP3A4 inducers. Combining them creates unpredictable effects on drug metabolism, potentially causing auto-induction of carbamazepine's own metabolism, leading to subtherapeutic anticonvulsant levels and increased seizure risk.
Mechanism. Carbamazepine is both a CYP3A4 substrate and inducer (auto-induction). St. John's Wort additionally induces CYP3A4 via PXR activation. The combined induction can accelerate carbamazepine metabolism beyond its auto-induction plateau, potentially reducing levels below the therapeutic range.
Recommendation. Avoid combining St. John's Wort with carbamazepine. The dual CYP induction creates unpredictable drug levels and may compromise seizure control. Monitor carbamazepine levels closely if the combination cannot be avoided.
Stack Score
How this pair moves the number.
Effect on the composite score
If both Carbamazepine and St. John's Wort are in the same stack, this pair applies −10 to your Stack Score (per scored conflict row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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