What kind of interaction is it?

Conflict: combining the two is generally not recommended without clinician oversight.

Is this interaction backed by published research?

Yes. NutriStack lists 2 citation rows for the St. John's Wort + Ticagrelor pair, each linking to PubMed by PMID where available. Full sourcing methodology at https://nutristackapp.com/methodology/interactions.

Interaction databaseSupplement × PrescriptionReviewed May 2026

St. John's Wort and Ticagrelor, a conflict.

Q: Can I take St. John's Wort and Ticagrelor together?

Generally not recommended together. St. John's Wort and Ticagrelor have a documented conflict. Ticagrelor is metabolised by CYP3A4 and is a P-glycoprotein substrate. St. John's wort potently induces both, and the model CYP3A4/P-gp inducer rifampin reduces ticagrelor AUC by 86% and Cmax by 73%, with a measurable loss of platelet inhibition. The same effect is expected with St. John's wort, risking treatment failure (stent thrombosis, MI, stroke).

Q: How does this affect a NutriStack Stack Score?

-10 to your Stack Score per scored conflict row.

Ticagrelor is metabolised by CYP3A4 and is a P-glycoprotein substrate. St. John's wort potently induces both, and the model CYP3A4/P-gp inducer rifampin reduces ticagrelor AUC by 86% and Cmax by 73%, with a measurable loss of platelet inhibition. The same effect is expected with St. John's wort, risking treatment failure (stent thrombosis, MI, stroke).

2 primary source citations. Moderate evidence. Last verified May 30, 2026.

Open the interaction checker →Read the methodology

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.

Sourcing standards·Evidence tiers

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 Ticagrelor
Pair type: Conflict
Evidence (highest tier): Moderate
Source citations: 2 sources
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. Ticagrelor is metabolised by CYP3A4 and is a P-glycoprotein substrate. St. John's wort potently induces both, and the model CYP3A4/P-gp inducer rifampin reduces ticagrelor AUC by 86% and Cmax by 73%, with a measurable loss of platelet inhibition. The same effect is expected with St. John's wort, risking treatment failure (stent thrombosis, MI, stroke).

Mechanism. Hyperforin in St. John's wort activates the pregnane X receptor, strongly inducing CYP3A4 and P-glycoprotein. Ticagrelor and its active metabolite are CYP3A4-dependent and P-gp substrates. Induction lowers ticagrelor exposure and the resulting platelet inhibition.

Recommendation. Avoid St. John's wort while on ticagrelor. If you have been taking both, stop the St. John's wort and tell your prescriber so antiplatelet adequacy can be reassessed (e.g., platelet reactivity testing if available).

Sources (2)

Stack Score

How this pair moves the number.

Effect on the composite score

If both St. John's Wort and Ticagrelor 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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