NutriStack
Black Cohosh and Green Tea Extract, a caution.
Concentrated Green Tea Extract is one of the botanicals most consistently linked to liver injury in the US Drug-Induced Liver Injury Network, and Black Cohosh has also been reported (though with weaker, more disputed causality). Taking them together means simultaneously exposing the liver to two agents that have each been associated with hepatitis, cholestasis, or, rarely, acute liver failure. Reported latency for either ranges from a few weeks to several months. The combined risk is most relevant in people who also drink alcohol, take other hepatotoxic agents, fast before dosing, or have pre-existing liver disease.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
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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 Green Tea Extract
- Pair type
- Caution
- Evidence (highest tier)
- Emerging
- Source citations
- 4 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. Concentrated Green Tea Extract is one of the botanicals most consistently linked to liver injury in the US Drug-Induced Liver Injury Network, and Black Cohosh has also been reported (though with weaker, more disputed causality). Taking them together means simultaneously exposing the liver to two agents that have each been associated with hepatitis, cholestasis, or, rarely, acute liver failure. Reported latency for either ranges from a few weeks to several months. The combined risk is most relevant in people who also drink alcohol, take other hepatotoxic agents, fast before dosing, or have pre-existing liver disease.
Mechanism. Additive idiosyncratic hepatotoxicity. Black Cohosh is among the botanicals reported in connection with herb-induced liver injury, with the proposed mechanism being oxidative stress and formation of reactive protein adducts in hepatocytes that may act as autoantigens, potentially triggering an immune-mediated hepatitis (note that expert causality reviews have found most reported cases to be only possible rather than probable, often with confounders). Concentrated Green Tea Extract (high in EGCG) is more firmly established as a botanical cause of drug-induced liver injury, driven by dose-dependent oxidative hepatocellular stress. Stacking two agents each capable of hepatic stress plausibly compounds cumulative oxidative burden on the liver and may raise the probability of an idiosyncratic injury event.
Recommendation. Avoid routinely stacking standardized Black Cohosh with high-dose Green Tea Extract (especially EGCG concentrates taken on an empty stomach). If both are used, keep each within label doses, take Green Tea Extract with food, limit alcohol, and consider baseline plus periodic liver enzymes (ALT, AST, bilirubin) at roughly 4 to 8 weeks. Stop both immediately and seek care for dark urine, jaundice, right upper quadrant pain, nausea, or unexplained fatigue. Prefer brewed green tea over concentrated extract if hepatotoxic stacking is a concern.
Minimum separation. Not a timing-separable interaction; the concern is cumulative exposure rather than co-ingestion at the same moment, so separating doses does not eliminate risk.
Sources (4)
- LiverTox: Clinical and Research Information on Drug-Induced Liver Injury, Black Cohosh monograph, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NCBI Bookshelf.
- LiverTox: Clinical and Research Information on Drug-Induced Liver Injury, Green Tea and Green Tea Extract monograph, NIDDK, NCBI Bookshelf.
- Adnan M, et al. Black Cohosh and Liver Toxicity: Is There a Relationship? Case Reports in Gastrointestinal Medicine, 2014.
- Drug-Induced Liver Injury Network (DILIN) analyses of herbal and dietary supplement hepatotoxicity, published in hepatology and gastroenterology literature.
Stack Score
How this pair moves the number.
Effect on the composite score
If both Black Cohosh and Green Tea Extract 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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