NutriStack
St. John's Wort and Verapamil, a conflict.
St. John's Wort induces CYP3A4, the primary enzyme metabolizing verapamil. This can reduce verapamil levels by 40-80%, leading to loss of heart rate/blood pressure control and breakthrough arrhythmias.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.
From the interaction database
What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- St. John's Wort and Verapamil
- Pair type
- Conflict
- Evidence (highest tier)
- Strong
- 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 · Strong evidence
Conflict
What is happening. St. John's Wort induces CYP3A4, the primary enzyme metabolizing verapamil. This can reduce verapamil levels by 40-80%, leading to loss of heart rate/blood pressure control and breakthrough arrhythmias.
Mechanism. Verapamil is extensively metabolized by CYP3A4 with high first-pass effect. CYP3A4 induction by hyperforin dramatically increases verapamil clearance and reduces its bioavailability.
Recommendation. Avoid St. John's Wort with verapamil. Loss of rate control can be dangerous in atrial fibrillation patients.
Stack Score
How this pair moves the number.
Effect on the composite score
If both St. John's Wort and Verapamil 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.
Check your full routine
One pair was the worked example. NutriStack runs every pair in your stack at once.
Drop in your supplements and prescriptions and the public database surfaces every interaction, synergy, timing rule, and contraindication, every one linked to its primary source.