Black cohosh and cancer

Black cohosh is a herb. There is no scientific evidence that black cohosh can treat or prevent cancer.


  • Black cohosh is a herb that belongs to the same plant family as the buttercup.
  • There is no scientific evidence that it can treat or prevent cancer.
  • Black cohosh might have side effects.

What is black cohosh?

Black cohosh is a herb that grows in North America (the USA and Canada). It belongs to the same plant family as the buttercup.

Its scientific name is actaea racemosa or cimicifuga racemosa. 

It is also called:

  • black snakeroot
  • macrotys
  • bugbane
  • bugwort
  • squawroot
  • rattleroot
  • rattleweed
  • rattlesnake root

Why people with cancer use it

Health food shops and online shops sell black cohosh. Manufacturers say that it can help reduce period cramps and discomfort. Many women use it to help with the symptoms and side effects of menopause, such as hot flushes. But the evidence for this is not clear.

Some women with breast cancer use black cohosh to help control menopause symptoms caused by their cancer treatment. But there isn’t enough scientific evidence to prove that this works. It is not clear how black cohosh affects the tissues of the womb (uterus) and vagina. And we can’t be sure that it’s safe to take black cohosh after breast cancer treatment.

How you have it

Black cohosh comes as:

  • dried extracts in capsules or tablets
  • whole herb
  • liquid extracts

Talk to your doctor before you have any type of complementary or alternative medicine.

What are the side effects of black cohosh?

Side effects are rare with small to moderate amounts of black cohosh. Most studies have used black cohosh for less than 6 months, so we don’t know about its long-term effects. We need more research to find out, and to be sure it's safe to have.

Common side effects are stomach pain, feeling or being sick, or skin rashes.

Other possible side effects might include:

  • breast pain
  • breasts getting larger
  • infection
  • vaginal bleeding
  • muscle and joint problems

There have been a few reports of black cohosh causing severe damage to the liver. It is not clear whether black cohosh was responsible for the liver damage. But the Medicines and Healthcare products Regulatory Agency (MHRA) say that all black cohosh products should carry a warning label.

Before having black cohosh

Talk to your doctor first if you are thinking about taking black cohosh. It may not be safe or suitable for you to take. Some doctors recommend that you shouldn’t take black cohosh for more than 6 months at a time.

You shouldn’t take black cohosh if you:

  • have breast cancer
  • have liver or kidney problems
  • have a type of chemotherapy called cisplatin
  • take a type of medicine called Atorvastatin (Lipitor) for high cholesterol
  • take medications that are changed by the liver
  • take other medications that can harm the liver
  • have blood pressure problems or take medicines for your blood pressure
  • are pregnant or breastfeeding

Research into black cohosh and cancer

We need more research to learn if black cohosh is safe to take and how it can help people with cancer. Many of the studies so far have been small or were not controlled trials. A controlled trial is where researchers give the control group a dummy drug (placebo). They then compare the results to a group having the new treatment.

Remifemin is a common brand of black cohosh. Some early clinical trials showed that Remifemin helped to relieve menopausal symptoms. Others showed that it didn't.

A review of the literature and meta analysis Open a glossary item in 2023, suggests that black cohosh may help some women experiencing hot flushes. It did not seem to help with anxiety due to the menopause.  

More research is needed with larger numbers of women. Future research should be more precise about the type and quality of black cohosh they use. This is so that other researchers can use the same type.

Several studies looked into black cohosh to see if it is a safe and helpful treatment for women with breast cancer or who had breast cancer.

Some researchers thought that black cohosh might affect the body in a similar way to the hormone oestrogen. If so, it might trigger breast cancer cells to grow. This is especially so in women where oestrogen affects their type of breast cancer. Doctors call this type of cancer oestrogen receptor positive breast cancer.

But, other research suggested that black cohosh did not cause oestrogen-like activity. It behaved more like nerve signal transmitters. A nerve signal transmitter is a chemical that helps to carry an impulse between one nerve and the next.

A systemic review in 2014 looked at women who'd had treatment for breast cancer and were taking black cohosh. The review showed mixed results with helping hot flushes. This means some studies showed a benefit but others didn't. 

Getting accurate results in these studies was difficult. The researchers used different amounts of black cohosh from various sources. The studies also had different aims. It may be that the benefits of black cohosh on menopausal symptoms may be due to a placebo effect. Open a glossary item

The 2014 systematic review found no significant link between black cohosh and the risk of breast cancer. But more studies are needed. 

Researchers did a laboratory study in 2018. They found that black cohosh might protect against getting breast cancer. It also suggested that it might stop breast cancer cells from growing.

The researchers thought that black cohosh might influence the hormone receptors on cells. But we need more research. Only then can these findings become a potential treatment against getting breast cancer.

How much it costs

There are many black cohosh products. Prices vary depending on where you buy it and the dosage.

You can buy black cohosh remedies in health food shops, pharmacies or supermarkets. They are also available over the internet. Registered practitioners of Western herbal medicine also sell black cohosh.

The amount of black cohosh in each product can vary.

Only buy registered products under the Traditional Herbal Remedies (THR) scheme. Look for the THR logo on the product. They have had tests for quality and safety.

A word of caution

It is understandable that you might want to try anything if you think it might help treat or cure your cancer. Only you can decide whether to use an alternative cancer therapy such as black cohosh.

You could harm your health if you stop your cancer treatment for an unproven treatment.

Some websites might promote black cohosh as part of treatment for cancer. But no reputable scientific cancer organisations support any of these claims.

Useful organisations

The National Institute for Medical Herbalists gives information about western herbal medicine and also has a register of UK herbal medicine practitioners.

Clover House
James Court
South Street

Tel: 01392 426022


Phytotherapists (phyto means plant in Greek) are herbal practitioners with specialist university training. They combine medical knowledge and skills with a scientific understanding of plant medicines. The organisation provides information and has a list of practitioners in the UK.

Oak Glade
9 Hythe Close
East Sussex
BN26 6LQ

Tel: 01323 484353

CNHC is the UK regulator for complementary healthcare practitioners. It protects the public by giving them access to a list of practitioners who have met national standards of competence and practice. Registered practitioners can use the CNHC quality mark on certificates and publicity materials. Most NHS services only use CNHC registered practitioners.

PO Box 428
Bristol BS9 0FB

Phone: 020 3327 2720 

The Memorial Sloan-Kettering Cancer Centre is a leading cancer hospital and research centre in New York. Its Integrative Medicine service was founded in 1999. It carries out research into the effectiveness of complementary therapies for cancer.

The website has a searchable database of herbs, vitamins and plants. It lists side effects, drug interactions, clinical information and clinical trials.


CAM-Cancer is a non-profit web resource that gives health professionals reliable information about complementary and alternative medicine (CAM) for cancer. It is managed by the Norwegian National Research Center for Complementary and Alternative Medicine (NAFKAM).

  • Black cohosh extracts in women with menopausal symptoms: an updated pairwise meta-analysis
    S Ryoichi and others
    Menopause The Journal Of The North American Menopause Society, 2023. Volume 30, Issue 7, Pages 766-773

  • Review and meta-analysis: isopropanolic black cohosh extract iCR for menopausal symptoms - an update on the evidence
    C.Castelo-Branco and others 
    Climacteric, 2021. Volume 24, Issue 2 

  • The effects of black cohosh on the regulation of estrogen receptor (ERα) and progesterone receptor (PR) in breast cancer cells
    M Szmyd and others
    Breast Cancer (Dove Med Press). 2018; 10: 1–11.

  • Black cohosh and breast cancer: a systematic review
    H Fritz and others
    Integrative cancer therapies, 2014. Volume 13, Issue 1, Pages 12-29 

  • Black cohosh, hot flushes, and breast cancer
    J Stebbing
    The Lancet, vol.16, 137-138, February 2015

  • Black cohosh
    Electronic Medicines Compendium (EMC)
    Accessed July 2022

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. If you need additional references for this information please contact with details of the particular issue you are interested in.

Last reviewed: 
29 Jul 2022
Next review due: 
29 Jul 2025

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