What kind of interaction is it?

Contraindicated: the two should not be combined; the risk outweighs any benefit.

Is this interaction backed by published research?

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

Interaction databaseSupplement × PrescriptionReviewed May 2026

Combined Oral Contraceptive and St. John's Wort, contraindicated.

Q: Can I take Combined Oral Contraceptive and St. John's Wort together?

No. Combined Oral Contraceptive and St. John's Wort are contraindicated together. St. John's Wort induces CYP3A4, dramatically reducing levels of ethinyl estradiol and progestins. This causes contraceptive failure and unintended pregnancy. The FDA and WHO list this as a contraindication.

Q: How does this affect a NutriStack Stack Score?

-25 to your Stack Score per scored contraindication row.

St. John's Wort induces CYP3A4, dramatically reducing levels of ethinyl estradiol and progestins. This causes contraceptive failure and unintended pregnancy. The FDA and WHO list this as a contraindication.

2 primary source citations. Strong 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: Combined Oral Contraceptive and St. John's Wort
Pair type: Contraindicated
Evidence (highest tier): Strong
Source citations: 2 sources
Stack Score effect: −25 to your Stack Score (per scored contraindication row).
Scope: Supplement × Prescription
Last verified: May 30, 2026

Contraindicated · Strong evidence

Contraindicated

What is happening. St. John's Wort induces CYP3A4, dramatically reducing levels of ethinyl estradiol and progestins. This causes contraceptive failure and unintended pregnancy. The FDA and WHO list this as a contraindication.

Mechanism. Ethinyl estradiol and progestins (levonorgestrel, norethindrone, etc.) are CYP3A4 substrates. SJW-mediated CYP3A4 induction reduces their levels below effective contraceptive concentrations.

Recommendation. Do NOT take St. John's Wort with oral contraceptives. Use alternative contraception (non-hormonal) if taking SJW. Multiple documented cases of unintended pregnancy.

Sources (2)

Stack Score

How this pair moves the number.

Effect on the composite score

If both Combined Oral Contraceptive and St. John's Wort are in the same stack, this pair applies −25 to your Stack Score (per scored contraindication row).

The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.

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