NutriStack
Dutasteride and St. John's Wort, a conflict.
Dutasteride exposure is vulnerable to CYP3A-related changes, and St. John's Wort is a clinically important inducer of CYP3A4 and P-glycoprotein. Direct St. John's Wort-dutasteride coadministration data are limited, but dutasteride has documented CYP3A-mediated interaction potential and St. John's Wort has well-established induction effects. The practical concern is reduced dutasteride exposure and less complete DHT suppression during chronic BPH or alopecia treatment.
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
- Dutasteride and St. John's Wort
- Pair type
- Conflict
- Evidence (highest tier)
- Emerging
- Source citations
- 3 sources
- Stack Score effect
- −10 to your Stack Score (per scored conflict row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Conflict · Emerging evidence
Conflict
What is happening. Dutasteride exposure is vulnerable to CYP3A-related changes, and St. John's Wort is a clinically important inducer of CYP3A4 and P-glycoprotein. Direct St. John's Wort-dutasteride coadministration data are limited, but dutasteride has documented CYP3A-mediated interaction potential and St. John's Wort has well-established induction effects. The practical concern is reduced dutasteride exposure and less complete DHT suppression during chronic BPH or alopecia treatment.
Mechanism. Dutasteride undergoes CYP3A-mediated metabolism, and CYP3A inhibition has altered dutasteride pharmacokinetics in experimental interaction studies. St. John's Wort activates pregnane X receptor signaling, inducing CYP3A4 and P-glycoprotein, which can lower exposure to susceptible substrates.
Recommendation. Avoid St. John's Wort while taking dutasteride unless the prescriber specifically approves it. Do not adjust dutasteride dosing yourself; instead, report any worsening urinary symptoms or hair-loss control after starting or stopping St. John's Wort.
Sources (3)
- Seo SW, Park JW, Han DG, Kim JM, Kim S, Park T, et al. In Vitro and In Vivo Assessment of Metabolic Drug Interaction Potential of Dutasteride with Ketoconazole. Pharmaceutics. 2019;11(12):673. PMID 31835695
- Villapalos-Garcia G, Zubiaur P, Navares-Gomez M, Saiz-Rodriguez M, Mejia-Abril G, Martin-Vilchez S, et al. Effects of Cytochrome P450 and Transporter Polymorphisms on the Bioavailability and Safety of Dutasteride and Tamsulosin. Front Pharmacol. 2021;12:718281. PMID 34690761
- Nicolussi S, Drewe J, Butterweck V, Meyer Zu Schwabedissen HE. Clinical relevance of St. John's wort drug interactions revisited. Br J Pharmacol. 2020;177(6):1212-1226. PMID 31742659
Stack Score
How this pair moves the number.
Effect on the composite score
If both Dutasteride 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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