NutriStack
Black Cohosh and St. John's Wort, a caution.
Both herbs carry independent hepatic safety signals, so combining them can complicate monitoring and attribution if liver enzymes rise or symptoms of liver injury appear.
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
- Black Cohosh and St. John's Wort
- Pair type
- Caution
- Evidence (highest tier)
- Emerging
- Source citations
- 2 sources
- Stack Score effect
- −5 to your Stack Score (per scored caution row).
- Scope
- Supplement × Supplement
- Last verified
- May 30, 2026
Caution · Emerging evidence
Caution
What is happening. Both herbs carry independent hepatic safety signals, so combining them can complicate monitoring and attribution if liver enzymes rise or symptoms of liver injury appear.
Mechanism. Black cohosh has been associated with idiosyncratic hepatocellular injury in pharmacovigilance reports, and St. John's Wort has its own rare hepatic reports plus potent induction of CYP enzymes and P-glycoprotein; overlapping use makes early detection and attribution of any liver toxicity more difficult.
Recommendation. Avoid routine co-use. If both are taken, watch for signs of liver injury (fatigue, dark urine, jaundice, right upper quadrant pain) and consider baseline and periodic liver function tests.
Sources (2)
- European Medicines Agency, Assessment report on Cimicifuga racemosa rhizome, 2018
- Borrelli F, Ernst E, Black cohosh (Cimicifuga racemosa): a systematic review of adverse events, American Journal of Obstetrics and Gynecology, 2008. Black cohosh (Cimicifuga racemosa): a systematic review of adverse events. Am J Obstet Gynecol. 2008. PMID 18984078
Stack Score
How this pair moves the number.
Effect on the composite score
If both Black Cohosh and St. John's Wort are in the same stack, this pair applies −5 to your Stack Score (per scored caution row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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