Black cohosh

What it is

Black cohosh is a perennial plant native to eastern North America, and supplements are made from its roots and rhizomes. Its constituents include triterpene glycosides and polyphenols. It was once thought to act like an oestrogen; more recent work points instead to serotonergic activity. Chemical analysis has repeatedly found products labelled black cohosh that actually contain Chinese Actaea species such as C. dahurica, C. foetida or C. heracleifolia.

What the research says

Black cohosh is taken for menopausal symptoms, and the literature on whether it works genuinely disagrees with itself. A 2012 Cochrane review of 16 trials in 2,027 women found no significant difference from placebo in hot flush frequency and rated the trials' quality generally unclear. A 2023 pairwise meta-analysis of 22 articles in 2,310 women found a moderate benefit for overall symptoms and hot flushes, but none for anxiety or depression. The European Medicines Agency accepts it for menopausal complaints under a 'well-established use' standard. The safety picture is the reverse of saw palmetto's: trials show few side effects, but more than fifty cases of clinically apparent liver injury, including acute liver failure requiring transplantation or causing death, have been reported in people taking products labelled black cohosh, and in several of those cases the product turned out to contain a different species.

Evidence grade: Disputed.

What goes wrong

More than fifty cases of clinically apparent liver injury, up to acute liver failure requiring transplantation or causing death, have been reported in people taking products labelled black cohosh. (Source 1)

• Expert review, not systematic, Low certainty.
• Size: More than fifty reported instances; set against prospective trials in more than 1200 patients with no cases.
• Who: People taking products labelled as black cohosh.
• How long: Latency 1 to 48 weeks, usually 2 to 12 weeks.
• Result: Range from asymptomatic enzyme elevation to acute liver failure; LiverTox likelihood score A.
• Funding: US government agency resource (NIDDK/NIH)

However, products labeled as black cohosh have been linked to more than fifty instances of clinically apparent liver injury that have ranged in severity from symptomatic elevations in serum enzymes without jaundice, to acute self-limited hepatitis, prolonged hepatitis with cholestasis, autoimmune hepatitis, and acute liver failure requiring liver transplantation or with a fatal outcome.

In several liver injury cases the implicated product was retrieved and found to contain Chinese Actaea species rather than black cohosh, leaving the role of Actaea racemosa itself unresolved. (Source 1)

• Expert review, not systematic, Low certainty.
• Size: Several of the reported liver injury cases.
• Who: People taking products labelled as black cohosh.
• How long: Not applicable.
• Result: Causal attribution to Actaea racemosa remains contested.
• Funding: US government agency resource (NIDDK/NIH)

In several instances, the implicated product has been retrieved and found to contain Chinese Actaea species rather than black cohosh, and the role of Actaea racemosa in causing liver injury remains controversial.

Phytochemical analysis has found black cohosh products that are mislabelled and contain Chinese Actaea species instead. (Source 2)

• Expert review, not systematic, Low certainty.
• Size: Not quantified in this summary.
• Who: Commercial black cohosh products.
• How long: Not applicable.
• Result: Substitution with C. dahurica, C. foetida and C. heracleifolia documented.
• Funding: US government agency resource (NIDDK/NIH)

Phytochemical analyses have shown that some black cohosh products are mislabeled and contain Chinese Actaea species instead (such as C. dahurica, C. foetida and C. heracleifolia).

The EMA's public summary lists liver problems as a side effect of black cohosh medicines and tells patients to stop and seek help on symptoms of liver injury. (Source 3)

• Official position, Certainty not rated.
• Size: Not quantified; frequency stated as unknown.
• Who: Adult women taking licensed black cohosh medicines in the EU.
• How long: Not applicable.
• Result: Frequency of these side effects is stated to be unknown.
• Funding: European Medicines Agency, HMPC, 2018.

Side effects with black cohosh medicines include liver problems, allergic skin reactions (such as rash and itchiness), swelling of the face and extremities, and symptoms affecting the gut such as indigestion and diarrhoea. The frequency of these side effects is unknown.

What the evidence supports

An updated 2023 pairwise meta-analysis found black cohosh extracts significantly improved overall menopausal symptoms and hot flashes compared with placebo. (Source 4)

• Meta-analysis, Low certainty.
• Size: 2,310 menopausal women across 22 articles.
• Who: Menopausal women.
• How long: Not stated in the abstract.
• Result: Overall symptoms Hedges' g = 0.575 (95% CI 0.283 to 0.867, P < 0.001); hot flashes g = 0.315 (95% CI 0.107 to 0.524, P = 0.003); somatic symptoms g = 0.418 (95% CI 0.165 to 0.670, P = 0.001)
• Funding: not stated.

Black cohosh extracts were associated with significant improvements in overall menopausal symptoms (Hedges' g = 0.575, 95% CI = 0.283 to 0.867, P < 0.001), as well as in hot flashes (Hedges' g = 0.315, 95% CIs = 0.107 to 0.524, P = 0.003), and somatic symptoms (Hedges' g = 0.418, 95% CI = 0.165 to 0.670, P = 0.001), compared with placebo.

The European Medicines Agency's herbal committee accepts black cohosh dry extracts for menopausal complaints on a well-established use basis, while listing liver problems among the side effects. (Source 3)

• Official position, Certainty not rated.
• Size: Around 20 clinical studies involving over 6,000 patients who received black cohosh.
• Who: Adult women with menopausal complaints.
• How long: Use beyond 6 months requires medical consultation.
• Result: No pooled effect size published in the public summary.
• Funding: European Medicines Agency, HMPC; monograph revision 1 published 03/07/2018 (first version 20/01/2011)

In its assessment, the HMPC considered around 20 clinical studies involving over 6,000 patients who received black cohosh. Results of the studies taken together indicate that black cohosh improves menopausal symptoms.

What the evidence does not support

A Cochrane review found no significant difference between black cohosh and placebo in the frequency of hot flushes or in menopausal symptom scores. (Source 5)

• Systematic review, Low certainty.
• Size: 393 women across three trials for hot flush frequency; 357 women across four trials for symptom scores (16 trials, 2,027 women overall)
• Who: Perimenopausal and postmenopausal women.
• How long: Mean duration 23 weeks.
• Result: Hot flushes MD 0.07 per day (95% CI -0.43 to 0.56), P=0.79, I2 = 47%; symptom scores SMD -0.10 (95% CI -0.32 to 0.11), P = 0.34, I2 = 21%.
• Funding: not stated.

There was no significant difference between black cohosh and placebo in the frequency of hot flushes (mean difference (MD) 0.07 flushes per day; 95% confidence interval (CI) -0.43 to 0.56 flushes per day; P=0.79; 393 women; three trials; moderate heterogeneity: I2 = 47%)

The same 2023 meta-analysis found no significant effect on anxiety or on depressive symptoms. (Source 4)

• Meta-analysis, Low certainty.
• Size: Subsets of the 2,310 women across 22 articles.
• Who: Menopausal women.
• How long: Not stated in the abstract.
• Result: Anxiety Hedges' g = 0.194 (95% CI -0.296 to 0.684, P = 0.438); depressive symptoms g = 0.406 (95% CI -0.121 to 0.932, P = 0.131)
• Funding: not stated.

However, black cohosh did not significantly improve anxiety (Hedges' g = 0.194, 95% CI = -0.296 to 0.684, P = 0.438) or depressive symptoms (Hedges' g = 0.406, 95% CI = -0.121 to 0.932, P = 0.131).

Hormone therapy outperformed black cohosh on menopausal symptom scores in head-to-head trials. (Source 5)

• Systematic review, Low certainty.
• Size: 468 women across five trials.
• Who: Perimenopausal and postmenopausal women.
• How long: Mean 23 weeks across the review.
• Result: SMD 0.32 (95% CI 0.13 to 0.51), P=0.0009, I2 = 69%, favouring hormone therapy.
• Funding: not stated.

Compared to black cohosh, hormone therapy significantly reduced daily hot flush frequency (three trials; data not pooled) and menopausal symptom scores (SMD 0.32; 95% CI 0.13 to 0.51; P=0.0009; 468 women; five trials; substantial heterogeneity: I2 = 69%).

The Cochrane reviewers judged the trials' quality generally unclear and said the safety evidence was inconclusive because of poor reporting. (Source 5)

• Systematic review, Low certainty.
• Size: 16 trials, 2,027 women.
• Who: Perimenopausal and postmenopausal women.
• How long: Mean 23 weeks.
• Result: No pooled safety estimate could be produced.
• Funding: not stated.

Similarly, evidence on the safety of black cohosh was inconclusive, owing to poor reporting.

Prospective trials in more than 1,200 patients found no serum enzyme elevations and no clinically apparent liver injury, which is why causality for the case reports is contested. (Source 1)

• Expert review, not systematic, Low certainty.
• Size: More than 1200 patients in prospective clinical trials.
• Who: Trial participants taking black cohosh.
• How long: Trial durations not specified in the summary.
• Result: No cases of clinically apparent liver injury reported in trials.
• Funding: US government agency resource (NIDDK/NIH)

In prospective clinical trials involving more than 1200 patients, black cohosh was not associated with serum enzyme elevations during treatment and no cases of clinically apparent liver injury were reported.

Where the evidence is mixed

NIH's complementary health centre records the 2023 evidence as potentially beneficial for overall menopause symptoms and hot flashes but not for anxiety or depression, and notes contamination of commercial products. (Source 6)

• Official position, Certainty not rated.
• Size: Refers to a 2023 review of 22 studies.
• Who: Menopausal women.
• How long: Safety described from studies lasting as long as a year.
• Result: No effect sizes given on the page.
• Funding: US government agency (NCCIH), page dated November 2024.

Some commercial black cohosh products have been found to contain the wrong herb or to contain mixtures of black cohosh and other herbs that are not listed on the label.

A narrative review of black cohosh in women's health summarises it as a traditionally used botanical for menopausal syndrome, without providing its own pooled estimates. (Source 7)

• Expert review, not systematic, Very low certainty.
• Size: Not applicable; no systematic search or pooled analysis stated.
• Who: Women with menopausal syndrome, mammary cancer and osteoporosis.
• How long: Not applicable.
• Result: No effect estimates reported.
• Funding: not stated.

Cimicifuga racemosa (CR or Black Cohosh) is a plant/herb which has been traditionally exploited and extensively used by women.

Where the research disagrees

Whether black cohosh relieves menopausal symptoms

• Leach and Moore, Cochrane 2012, Cochrane systematic review of 16 RCTs, trial quality judged generally unclear: The review of 16 studies (involving 2027 women) found insufficient evidence to support the use of black cohosh for menopausal symptoms. (Source 8)
• Authors of the 2023 updated pairwise meta-analysis, Menopause, pairwise random-effects meta-analysis of 22 articles, 2,310 women: Black cohosh extracts were associated with significant improvements in overall menopausal symptoms (Hedges' g = 0.575, 95% CI = 0.283 to 0.867, P < 0.001) (Source 4)
• EMA Committee on Herbal Medicinal Products, 2018, regulatory assessment of around 20 clinical studies under a well-established use standard: Results of the studies taken together indicate that black cohosh improves menopausal symptoms. (Source 3)

Whether black cohosh causes liver injury

• LiverTox (NIDDK/NIH), expert summary of more than fifty published case reports against prospective trial data: Likelihood score: A (products sold as black cohosh are well established causes of clinically apparent liver injury, but the specific ingredient or component that accounts for the injury is unclear). (Source 1)
• NCCIH (NIH), November 2024, agency summary of case reports and product contamination findings: These problems are rare, and it's uncertain whether black cohosh was responsible for them. (Source 6)

How much

• Reference intake: No reference intake (RDA or AI) exists. Black cohosh is a root and rhizome preparation taken as a herbal medicine, not an essential nutrient, so no body has set a dietary requirement. (Source 2)
• Upper limit: No tolerable upper intake level or ADI has been set. The EMA's HMPC (monograph revision 1, 2018) instead sets a duration limit for licensed medicines. (Source 3)
• Studied: All 16 trials in the Cochrane review used oral monopreparations at a median daily dose of 40 mg for a mean of 23 weeks. (Source 5)
• Studied: The EMA's assessment drew on around 20 clinical studies in over 6,000 patients who received black cohosh. (Source 3)

A common belief, and what the research shows

The belief: Black cohosh is a natural, side-effect-free substitute for hormone therapy at menopause.

What the research shows: Two things in that sentence do not survive the evidence. On effect, the head-to-head trials went the other way: 'Compared to black cohosh, hormone therapy significantly reduced daily hot flush frequency (three trials; data not pooled) and menopausal symptom scores (SMD 0.32; 95% CI 0.13 to 0.51; P=0.0009; 468 women; five trials; substantial heterogeneity: I2 = 69%).' On safety, LiverTox records that 'products labeled as black cohosh have been linked to more than fifty instances of clinically apparent liver injury' including liver failure, and the EMA lists liver problems among the side effects of licensed products.

Questions and answers

What is it?

Black cohosh is a perennial plant of eastern North America, used in traditional Native American medicine and now sold as a supplement made from its roots and rhizomes. Its active constituents are triterpene glycosides and polyphenols. It goes by many names on labels, including Cimicifuga racemosa, black snakeroot and bugbane. (Source 2)

What does it do in the body?

Its mechanism is not settled. It was originally assumed to act like an oestrogen at tissue-specific oestrogen receptors, but later work suggests a serotonergic action instead. That matters, because the oestrogen assumption is what drove concern about using it after hormone-sensitive cancers. (Source 2)

Is it good or bad for you?

The evidence is genuinely split. Cochrane in 2012 found no difference from placebo in hot flush frequency across three trials in 393 women, while a 2023 meta-analysis of 22 articles in 2,310 women found a moderate benefit for overall symptoms and hot flashes, and none for anxiety or mood. Against that sits a liver safety signal serious enough that European regulators warn about it, even though trial data show no liver problems. (Source 5)

How do you get more of it?

It is not a dietary component. It is taken as a manufactured extract, almost always a solid oral form such as a tablet or capsule made from a dried liquid extract of the root. Trials pooled by Cochrane used single-herb oral preparations at a median of 40 mg a day for an average of 23 weeks. (Source 3)

If it is harmful, what reduces it?

The action described in the literature is stopping the product. European regulators instruct patients to stop immediately and seek medical help if signs of liver injury appear. In the case reports summarised by LiverTox, hepatitis with autoimmune features sometimes resolved spontaneously after black cohosh was discontinued, and sometimes needed a course of prednisone. (Source 3)

Why might someone be low in it or missing it?

The question does not apply. Black cohosh is a herbal preparation taken deliberately for menopausal symptoms, not a nutrient the body needs, absorbs from food or can run short of. Nobody is low in black cohosh. (Source 2)

We searched: Searched LiverTox, NCCIH, the EMA HMPC public summary and the 2012 Cochrane review for any description of a black cohosh requirement, deficiency or depletion; none describes one, and all treat it as a treatment taken by choice.

Which whole foods contain it or feed it?

No whole food contains it and none feeds it. The part used is the underground root and rhizome of a woodland plant, prepared into supplements; it is not a culinary ingredient. Any exposure comes from a supplement or a licensed herbal medicine. (Source 2)

What happens if you do not have it?

Nothing happens, because there is no deficiency state. The relevant comparison is the placebo arms of the menopause trials, and those results are exactly what is disputed: Cochrane found comparisons with other interventions inconclusive or not statistically significant, while a later meta-analysis found a moderate symptom benefit for those who took it. (Source 5)

How can you test for it?

There is no clinical test for black cohosh in a person. The testing that matters is of the product itself, because botanical identity is a documented problem: commercial products have been found to contain the wrong herb, or undeclared mixtures. DNA and phytochemical methods can distinguish Actaea racemosa from Asian Actaea species, but a consumer cannot verify this from the label. (Source 6)

References

1. National Institute of Diabetes and Digestive and Kidney Diseases (NCBI Bookshelf). Black Cohosh — LiverTox: Clinical and Research Information on Drug-Induced Liver Injury (Hepatotoxicity). 2020. PMID 31643322. Read the source
2. National Institute of Diabetes and Digestive and Kidney Diseases (NCBI Bookshelf). Black Cohosh — LiverTox: Clinical and Research Information on Drug-Induced Liver Injury (Background). 2020. PMID 31643322. Read the source
3. European Medicines Agency, Committee on Herbal Medicinal Products (HMPC). Cimicifugae rhizoma (black cohosh) — herbal medicine summary for the public. 2018. Read the source
4. Menopause. Black cohosh extracts in women with menopausal symptoms: an updated pairwise meta-analysis (Sadahiro R, Matsuoka LN, Zeng B-S, et al.; last author Tseng P-T). 2023. PMID 37192826, DOI 10.1097/GME.0000000000002196. Read the source
5. Cochrane Database of Systematic Reviews. Black cohosh (Cimicifuga spp.) for menopausal symptoms (Abstract: Main results). 2012. PMID 22972105, DOI 10.1002/14651858.CD007244.pub2. Read the source
6. National Center for Complementary and Integrative Health (NIH). Black Cohosh: Usefulness and Safety. 2024. Read the source
7. Pharmaceuticals. Benefits of Black Cohosh (Cimicifuga racemosa) for Women Health: An Up-Close and In-Depth Review. 2022. PMID 35337076, DOI 10.3390/ph15030278. Read the source
8. Cochrane Database of Systematic Reviews. Black cohosh (Cimicifuga spp.) for menopausal symptoms (Plain language summary). 2012. PMID 22972105, DOI 10.1002/14651858.CD007244.pub2. Read the source