Black Cohosh
Actaea racemosa / Cimicifuga racemosa
TL;DR
Black cohosh is a root extract used at 20–40 mg twice daily for hot flushes. Evidence is mixed but favourable; rare liver injury reports warrant monitoring.
Ideal For
- Women with hot flushes and night sweats who cannot or prefer not to use hormone therapy
- Breast cancer survivors on tamoxifen, with oncology awareness
- Women with perimenopausal mood and sleep disruption
Avoid If
- You have liver disease or raised liver enzymes
- You are pregnant or breastfeeding
- You take hepatotoxic medications
- You have unexplained abdominal pain, dark urine or jaundice
Frequently Asked Questions
Is black cohosh a phytoestrogen?
How long until it helps hot flushes?
Is the liver risk real?
Can it be used with tamoxifen?
Overview
Black cohosh (Actaea racemosa) is a North American woodland plant used traditionally by Indigenous peoples and now among the most widely used botanicals for menopausal symptoms in Europe, where the standardised extracts iCR and BNO 1055 have been studied most.
Its mechanism is not oestrogenic, despite decades of assumption. Modern work indicates serotonergic activity at 5-HT7 receptors and possible dopaminergic effects, which fits the thermoregulatory nature of hot flushes better than an oestrogen model does. That matters clinically, because it means black cohosh does not stimulate breast or endometrial tissue in the way phytoestrogens might, and it has been studied in breast cancer survivors on tamoxifen.
Efficacy evidence is genuinely mixed. A Cochrane review found insufficient evidence overall, while several individual trials and later meta-analyses of standardised extracts report meaningful reductions in hot flush frequency and Kupperman index scores versus placebo. The pragmatic reading is that it helps some women modestly and is worth a 12-week trial. Rare cases of hepatotoxicity have been reported; causality is often unclear, but liver function should be checked if symptoms appear.
How It Works
- Acts on 5-HT7 serotonin receptors involved in central thermoregulation
- Possible dopaminergic activity affecting hypothalamic temperature set point
- Not oestrogen receptor binding — modern assays find no significant oestrogenic activity
- Triterpene glycosides including actein are considered the active constituents
- May modulate hypothalamic-pituitary signalling without changing FSH or LH
Quick Facts
- Reduces hot flashes
- Alleviates night sweats
- Improves sleep in menopause
- Mood support during menopause
- Non-estrogenic mechanism
Benefits & Outcomes
Hot Flash Reduction
Black cohosh is the most-studied herbal for hot flashes, with meta-analyses showing modest benefit over placebo in perimenopausal women.
Night Sweats Reduction
Modest benefit for menopausal sweats; trial results conflict.
Menopause Symptom Relief
Black cohosh has the strongest botanical evidence for vasomotor menopause symptoms, with meta-analyses showing significant hot flash reduction over placebo.
Improved Sleep Quality
Sleep improvements appear secondary to fewer night-time hot flushes rather than a direct hypnotic effect.
Mood Stabilization
Mood effects are inconsistent and confounded by symptom relief in menopausal cohorts.
Hormonal Balance
Black cohosh affects menopausal symptoms without measurably changing hormone levels.
Health Concerns Addressed
Hot Flashes
All three NIH-funded placebo-controlled trials were negative and the Cochrane review found no significant difference in hot flash frequency, while some meta-analyses report a small benefit concentrated in one extract.
Night Sweats
Mixed trial evidence for menopausal night sweats only; irrelevant to other causes, which must be ruled out first.
Menopause
Black cohosh may modestly reduce hot flushes, but trial results conflict and liver safety signals require attention.
Supporting Research18 studies
Safety and Efficacy of Black Cohosh and Red Clover for the Management of Vasomotor Symptoms: A Randomized Controlled Trial
Geller SE, Shulman LP, van Breemen RB +10 more
Neither red clover nor black cohosh reduced vasomotor symptoms significantly more than placebo over 12 months, while hormone therapy did.
In vivo effects of goldenseal, kava kava, black cohosh, and valerian on human cytochrome P450 1A2, 2D6, 2E1, and 3A4 phenotypes
Gurley BJ, Gardner SF, Hubbard MA +4 more
Goldenseal produced strong inhibition of both CYP2D6 (approximately 40%) and CYP3A4/5 (approximately 40%); the other botanicals had minimal effect.
Phase III double-blind, randomized, placebo-controlled crossover trial of black cohosh in the management of hot flashes: NCCTG Trial N01CC1
Pockaj BA, Gallagher JG, Loprinzi CL +4 more
failed to provide any evidence that black cohosh reduced hot flashes more than the placebo
Complementary therapies for management of menopausal symptoms: a systematic review to inform the update of the International Menopause Society recommendations on women's midlife health
Maunder A, Mardon AK, Rao V +4 more
moderate-certainty evidence supports black cohosh (vasomotor/menopausal symptoms)
Randomized trial of black cohosh for the treatment of hot flashes among women with a history of breast cancer
Jacobson JS, Troxel AB, Evans J +4 more
Black cohosh was not significantly more efficacious than placebo against most menopausal symptoms
Efficacy and safety of isopropanolic black cohosh extract for climacteric symptoms
Osmers R, Friede M, Liske E +3 more
effective in relieving climacteric symptoms, especially in early climacteric women
Cimicifuga racemosa dried ethanolic extract in menopausal disorders: a double-blind placebo-controlled clinical trial
Frei-Kleiner S, Schaffner W, Rahlfs VW +2 more
showed no superiority of the tested black cohosh extract compared to placebo
Black cohosh and breast cancer: a systematic review
Fritz H, Seely D, McGowan J +4 more
Current evidence does not support an association between black cohosh and increased risk of breast cancer
Review & meta-analysis: isopropanolic black cohosh extract iCR for menopausal symptoms - an update on the evidence
Castelo-Branco C, Gambacciani M, Cano A +4 more
iCR was significantly superior for treating neurovegetative and psychological menopausal symptoms
Vasomotor symptoms resulting from natural menopause: a systematic review and network meta-analysis of treatment effects from the National Institute for Health and Care Excellence guideline on menopause
Sarri G, Pedder H, Dias S +2 more
Isoflavones and black cohosh were more effective than placebo
Black cohosh (Cimicifuga spp.) for menopausal symptoms
Leach MJ, Moore V
There was no significant difference between black cohosh and placebo in the frequency of hot flushes or in menopausal symptom scores across the pooled trials.
Effects of herbal preparations on symptom clusters during the menopausal transition
Ismail R, et al.
Black cohosh mixed with other herbals, Rheum rhaponticum, and French maritime pine bark had significant effects on hot flushes and at least one other symptom.
Black cohosh extracts in women with menopausal symptoms: an updated pairwise meta-analysis
Sadahiro R, Matsuoka LN, Zeng BS +1 more
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)
Assessing the clinical significance of botanical supplementation on human cytochrome P450 3A activity: comparison of a milk thistle and black cohosh product to rifampin and clarithromycin
Gurley B, Hubbard MA, Williams DK +1 more
Milk thistle and black cohosh appear to have no clinically relevant effect on CYP3A activity in vivo.
Black cohosh (Cimicifuga racemosa) for menopausal symptoms
Leach MJ, Moore V
There was insufficient evidence that black cohosh reduced hot flushes or night sweats compared with placebo
Treatment of vasomotor symptoms of menopause with black cohosh, multibotanicals, soy, hormone therapy, or placebo: a randomized trial
Newton KM, Reed SD, LaCroix AZ +3 more
Black cohosh, multibotanical preparations and soy did not reduce vasomotor symptom frequency or intensity more than placebo at any timepoint, whereas hormone therapy did.
Efficacy of black cohosh extracts for improving low estrogen status induced by postoperative GnRHa treatment in patients with endometriosis: a systematic review
Peng J, Xu W, Li X +1 more
The addition of BCE did not alter hormone levels of patients, including serum estradiol levels [MD=1.24, 95% CI(-4.58, 7.08), P>0.05] and luteinizing hormone levels.
Suspected black cohosh hepatotoxicity: no evidence by meta-analysis of randomized controlled clinical trials for isopropanolic black cohosh extract
Naser B, Schnitker J, Minkin MJ +3 more
Pooled liver function data from randomized trials of isopropanolic black cohosh extract showed no signal of hepatotoxicity compared with placebo.
Safety Information
Potential Side Effects
Usually mild: stomach upset, headache, rash and occasional weight gain. The important rare risk is idiosyncratic liver injury, reported in case series across Europe and the US, which prompted labelling warnings in several countries.
Contraindications
Do not use with existing liver disease. Discontinue immediately and seek medical review if jaundice, dark urine, upper abdominal pain or unusual fatigue develops. Not for use in pregnancy — it has been used traditionally to induce labour.
Drug Interactions
- Hepatotoxic drugs including methotrexate and high-dose paracetamol — additive liver risk
- Tamoxifen — studied together with no evidence of interference, but discuss with oncology
- CYP2D6 substrates — weak inhibition reported in vitro
- Sedatives — possible additive drowsiness
Pregnancy & Breastfeeding
Pregnancy: Unsafe
Breastfeeding: Not enough evidence to judge
Dosage Guidelines
Dosage Used in Studies
20-40 mg
Best Time to Take
Morning and evening, split doses
Best Form
A standardised extract such as iCR or BNO 1055 from a supplier that verifies species identity
Bioavailability
Used for menopausal symptoms. Mechanism unclear - does not appear to be estrogenic. Rare cases of liver toxicity reported. Discontinue if liver symptoms develop. Effects may take 4-8 weeks.
Dosing by Goal
| Goal | Dose | Notes |
|---|---|---|
| Standard | 20 mg twice daily of standardised extract | |
| Range | 20-80 mg/day | |
| Trials | 40 mg/day for 12 weeks is the most common regimen | |
| Notes | Assess at 12 weeks; most guidance advises against continuous use beyond 6-12 months without review |
Forms Compared
iCR (Remifemin) standardised extract
The most studied preparation, 20 mg twice daily
BNO 1055 extract
European standardised extract with its own trial base
Crude root powder
Not standardised; potency and identity vary and adulteration with Asian Actaea species is documented
Food & Timing
With food to reduce stomach upset
Medical Disclaimer
The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.
Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.