Black cohosh (Actaea racemosa, formerly Cimicifuga racemosa) is a flowering plant native to eastern North America. Native American communities used the root for various ailments long before European colonists arrived, and by the mid-1950s it had become one of the most popular herbal remedies for women’s health issues in Europe and North America.

The underground rhizome contains the active compounds, including triterpene glycosides (particularly actein and 27-deoxyactein), isoferulic acid, and formononetin. These substances give the herb its characteristic bitter taste and may explain some of its physiological effects.

Despite decades of use, the exact mechanisms behind black cohosh remain incompletely understood. Early theories suggested it worked like a phytoestrogen, directly binding to oestrogen receptors. More recent research suggests this is probably not the case. Current thinking focuses on effects on serotonin receptors in the brain, which could explain benefits for hot flushes and mood without the hormonal concerns that come with actual oestrogen therapy 1.

One important clarification: do not confuse black cohosh with blue cohosh (Caulophyllum thalictroides) or white cohosh (Actaea pachypoda). These are botanically unrelated plants with different chemical profiles and safety considerations. Blue cohosh in particular has caused serious adverse events and should not be used interchangeably with black cohosh.

What is black cohosh used for?

The main applications centre on menopausal symptoms, though people have also used it for premenstrual syndrome, painful periods, and joint complaints. In Germany, standardised black cohosh extracts have been licensed medications for menopausal symptoms since 1989.

The supplement typically comes as tablets, capsules, or liquid extracts. Most clinical trials have used standardised extracts providing 1-2 mg of triterpene glycosides per dose, taken once or twice daily.

1. Menopausal symptoms

Menopause typically occurs around age 51 and brings a constellation of symptoms including hot flushes, night sweats, vaginal dryness, sleep disturbances, mood changes, and cognitive difficulties. These symptoms can persist for years—while most women find relief within two years, some experience symptoms for a decade or longer.

Hormone replacement therapy (HRT) remains the most effective treatment for menopausal vasomotor symptoms, but not everyone can or wants to use it. This has driven interest in alternatives like soy isoflavones, red clover, and black cohosh.

The research on black cohosh for menopause is genuinely mixed, and I think it is important to be upfront about that. A 2012 Cochrane systematic review examined 16 randomised controlled trials involving 2,027 women and concluded the evidence was insufficient to support or refute black cohosh for menopausal symptoms 2. The studies varied too much in design, dosage, and outcome measures to draw firm conclusions.

However, individual trials have shown more promising results. A 2013 double-blind study of 84 postmenopausal women found that black cohosh significantly reduced menopausal symptom scores compared to placebo over 8 weeks, with improvements in vasomotor symptoms (hot flushes and sweating), psychological symptoms, and physical complaints 3.

A larger 2006 study published in the Annals of Internal Medicine followed 351 women for 12 months and found that black cohosh (160 mg/day) produced modest improvements in vasomotor symptoms, though the effects were not dramatically different from placebo 4.

My take: The evidence suggests black cohosh might help some women with mild to moderate hot flushes, but don’t expect dramatic results. If you have severe vasomotor symptoms significantly affecting your quality of life, this probably won’t be enough on its own. It may be worth trying as a first-line option for mild symptoms or as an adjunct to other approaches, but keep expectations realistic.

2. Sleep disturbances during menopause

Sleep problems affect 28% to 63% of menopausal women. The disruption goes beyond simply feeling tired—chronic sleep deprivation increases risks for cardiovascular disease, metabolic disorders, anxiety, and cognitive decline over the long term.

The connection between menopause and poor sleep is complex. Hot flushes and night sweats directly wake women up, but even those without significant vasomotor symptoms often report worse sleep quality. Changes in progesterone, which has sedative properties, may contribute.

A 2015 randomised controlled trial examined 48 postmenopausal women over 6 months and found that black cohosh improved sleep efficiency and reduced wake time after sleep onset by 15.8% compared to placebo 5. Sleep quality scores also improved.

Worth noting: This is a small study, and we need larger trials to confirm these findings. If sleep is your main concern, you might also consider melatonin, which has stronger evidence for sleep disturbances, or address underlying causes like untreated hot flushes.

3. Bone health

Osteoporosis becomes a significant concern after menopause. The drop in oestrogen accelerates bone loss, and within 5-7 years of menopause, women can lose up to 20% of their bone density. This translates to increased fracture risk, particularly of the hip, spine, and wrist.

Some laboratory studies suggest black cohosh may have bone-protective effects. A 12-week randomised controlled trial involving 62 postmenopausal women found that black cohosh stimulated osteoblast (bone-building cell) activity and appeared to support bone remodelling 6.

However, a separate study found that when black cohosh was added to an exercise training programme, it did not provide additional benefits beyond exercise alone for bone density or body composition 7.

Reality check: The bone health data is preliminary at best. If you are concerned about osteoporosis, the proven interventions remain adequate calcium and vitamin D intake, weight-bearing exercise, not smoking, limiting alcohol, and medications like bisphosphonates if your bone density is significantly reduced. I would not rely on black cohosh for osteoporosis prevention.

Are there any side effects of black cohosh?

Black cohosh is generally well tolerated at recommended doses. The most common side effects are gastrointestinal—nausea, upset stomach, or diarrhoea. Some people report headaches, dizziness, or rash.

The National Institutes of Health notes that clinical trials lasting up to 12 months have not found serious safety concerns 8. Most adverse events in studies were mild and similar in frequency to placebo groups.

That said, there are important safety considerations to be aware of.

Liver concerns

Reports of liver damage associated with black cohosh use have caused significant concern. The Australian Therapeutic Goods Administration and European regulatory agencies have issued warnings, and some products now carry liver safety labels.

Here is what we actually know: a 2011 review of liver injury cases found 83 reports potentially linked to black cohosh worldwide 9. However, establishing causation is difficult. Many reports involved products with multiple ingredients, inadequate medical histories, or possible adulteration or misidentification of plant material.

The United States Pharmacopoeia reviewed the evidence and assigned black cohosh a Class II-B safety rating, meaning theoretical concerns exist based on case reports but there is not enough evidence to establish causality.

In practice: The risk appears to be low, but I would recommend monitoring for symptoms of liver problems—unusual fatigue, dark urine, jaundice (yellowing of eyes or skin), or abdominal pain—especially in the first few months of use. If you have pre-existing liver disease, it is sensible to avoid black cohosh or use it only under medical supervision.

Safety precautions (6 contraindications)

1. Hormone-sensitive conditions: Women with a history of breast cancer, endometriosis, uterine fibroids, or ovarian cancer should be cautious. While black cohosh does not appear to act as a direct oestrogen, we cannot completely rule out effects on hormone-sensitive tissues. The European Medicines Agency recommends women with a history of breast cancer consult their doctor before use 10.

2. Pregnancy and breastfeeding: Black cohosh should not be used during pregnancy. Some historical uses actually involved inducing labour, and animal studies suggest potential effects on uterine contractions. There is insufficient safety data during breastfeeding, so it is best avoided.

3. Liver disease: Given the case reports of hepatotoxicity, people with existing liver conditions should avoid black cohosh or use it only with medical supervision and monitoring.

4. Protein S deficiency: This rare clotting disorder may theoretically increase thrombosis risk with black cohosh use. If you have a known clotting disorder, discuss this with your doctor.

5. Aspirin or salicylate allergy: Some people with aspirin sensitivity have reported reactions to black cohosh. The connection is not well established, but caution is warranted if you have known salicylate sensitivity.

6. Drug interactions: Black cohosh may interact with:

Medications metabolised by liver enzymes (CYP2D6 substrates)
Blood pressure medications (may enhance effects)
Sedatives (may add to drowsiness)
Tamoxifen and other breast cancer drugs (theoretical interaction)

If you take prescription medications, check with a pharmacist before adding black cohosh.

How does black cohosh work?

The mechanism remains debated. Here is what the research suggests:

Early theories proposed black cohosh acted as a phytoestrogen, but studies have largely failed to confirm significant binding to oestrogen receptors alpha or beta. Blood levels of oestrogen and follicle-stimulating hormone (FSH) do not change with black cohosh use in most studies.

The current leading theory involves serotonin. The active triterpene compounds appear to bind to serotonin receptors, particularly 5-HT1A and 5-HT7. This could explain effects on hot flushes (which involve serotonin pathways in the brain’s thermoregulatory centre), mood, and sleep without hormonal effects.

Some components may also have anti-inflammatory properties, which could contribute to reported benefits for joint discomfort.

Other traditional uses

Beyond menopause, black cohosh has historical uses for:

Painful periods: Some women report relief from menstrual cramps, though clinical evidence is limited.
PMS: A few small studies suggest potential benefits for premenstrual symptoms.
Arthritis: Traditional use for joint pain, but modern evidence is sparse.

The scientific evidence for these uses is much weaker than for menopausal symptoms.

What about menopausal urinary symptoms?

Menopause can significantly affect bladder health. The same oestrogen decline that causes vaginal dryness can thin the urethral lining and alter bladder function. This condition, now called genitourinary syndrome of menopause, can cause urinary urgency, frequency, and increased susceptibility to urinary tract infections.

I could not find specific studies examining black cohosh for urinary symptoms. If you are experiencing menopausal urinary issues, local vaginal oestrogen (which has a better safety profile than oral HRT) is the most evidence-based treatment. See your doctor to discuss options.

Choosing a black cohosh product

Quality varies significantly among black cohosh supplements. Consider:

Standardisation: Look for products standardised to triterpene glycoside content (typically 1-2.5%)
Species verification: Ensure the product contains actual Actaea racemosa, not related species
Third-party testing: Brands that use independent testing for identity and purity are preferable
Form: Tablets and capsules are most commonly used in clinical trials; liquid extracts are also available

The typical dose in clinical studies is 20-40 mg of standardised extract twice daily, or equivalent preparations providing 1-2 mg triterpene glycosides per dose.

The bottom line

Black cohosh has a long history of use for menopausal symptoms and reasonable short-term safety data. The evidence for effectiveness is mixed—some women clearly find it helpful, while others notice no benefit. It is not a replacement for hormone therapy if you have severe symptoms, but may be worth trying for mild to moderate hot flushes, particularly if you prefer starting with a herbal approach.

If you are considering black cohosh, I would suggest:

Discuss it with your doctor, especially if you have any of the conditions mentioned in the contraindications
Choose a reputable, standardised product
Give it a fair trial of at least 8-12 weeks before deciding if it helps
Monitor for any unusual symptoms, particularly those suggesting liver problems
Recognise that individual responses vary considerably

For some women, this will be a useful addition to their menopause toolkit. For others, it simply will not do much. There is no way to predict which group you fall into without trying it.

References

Actaea racemosa and its biological activities - Natural Product Research, 2018
Black cohosh for menopausal symptoms - Cochrane Review - Cochrane Database Systematic Reviews, 2012
Effect of black cohosh on menopausal symptoms - Journal of Education and Health Promotion, 2013
Herbal Alternatives for menopause trial - Annals of Internal Medicine, 2006
Black cohosh on sleep quality - Climacteric, 2015
Bone metabolism effects of black cohosh - Phytomedicine, 2010
Black cohosh with exercise training - Osteoporosis International, 2009
NIH: Black Cohosh - National Center for Complementary and Integrative Health
Hepatotoxicity of botanical supplements - Clinical Liver Disease, 2011
EMA Black Cohosh Assessment - European Medicines Agency