NutriStack
Fluticasone Inhaled and St. John's Wort, a conflict.
St. John's Wort can induce CYP3A4, and fluticasone is cleared primarily by CYP3A4. Induction may lower systemic and possibly airway steroid exposure, which can reduce asthma or COPD controller effectiveness in some patients.
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
- Fluticasone Inhaled and St. John's Wort
- 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. St. John's Wort can induce CYP3A4, and fluticasone is cleared primarily by CYP3A4. Induction may lower systemic and possibly airway steroid exposure, which can reduce asthma or COPD controller effectiveness in some patients.
Mechanism. St. John's Wort induces intestinal and hepatic CYP3A4; fluticasone is a CYP3A4 substrate with very high first-pass metabolism. Increased CYP3A activity can plausibly reduce fluticasone exposure, though the size of effect depends on formulation, dose, and the St. John's Wort product.
Recommendation. Avoid starting St. John's Wort while relying on inhaled fluticasone for disease control unless your clinician agrees. If combined, monitor symptoms, peak flow if used, rescue inhaler use, and exacerbations after any St. John's Wort start or stop.
Sources (2)
- Whitten DL, Myers SP, Hawrelak JA, Wohlmuth H. The effect of St John's wort extracts on CYP3A: a systematic review of prospective clinical trials. Br J Clin Pharmacol. 2006;62(5):512-526. PMID 17010103
- Foisy MM, Yakiwchuk EM, Chiu I, Singh AE. Adrenal suppression and Cushing's syndrome secondary to an interaction between ritonavir and fluticasone: a review of the literature. HIV Med. 2008;9(6):389-396. PMID 18459946
Stack Score
How this pair moves the number.
Effect on the composite score
If both Fluticasone Inhaled 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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