Natural Products

Black Cohosh

Actea racemosa, Cimicifuga racemosa

Efficacy

• Indications with proven efficacy:
  None
• Indications with possible, but poorly documented efficacy:
  Dysmenorrhea
  Menopause symptoms
  Premenstrual symptoms
• Also used for these other indications, but with no proof of efficacy:
  Cough, expectoration
  Dyspepsia
  Hot flashes consecutive to breast cancer
  Hypertension
  Insect repellent
  Rheumatism
  Snake bites
  Sore throat

Security

• Risk of Drug Interactions: Low
• Adverse Effects: Not Frequent

What is it?

Black cohosh is a perennial plant found along the edge of North American forests, from Ontario to Tennessee, west of Missouri. The plant can reach 8 feet high and carries, from June to September, a long white flowerhead. The roots and rhizomes are used for their medicinal properties.

Black cohosh is not a well-known plant. It appears to contain estrogenic constituents, and some have feared that it could promote the proliferation of some cancerous cells with estrogenic receptors. However, scientific evidence has shown that black cohosh can inhibit the growth of breast cancer cells and some recent studies allow to doubt that the estrogenic effect is not the major mode of action. It also appears to enhance tamoxifen's anticarcinogenic effect. This information leads us to believe that black cohosh is not contraindicated in women with a history of breast cancer.

Remifemintm, a brand name of the standardized extract available in Canada, was used in clinical studies to establish black cohosh's effectiveness.

Warning

In 2004, Canada adopted new regulations that control the manufacturing, packaging, labeling and importing of natural health products. The new regulations also include an adverse reaction reporting system. Products that conform to the regulation's criteria are identified with a natural product number (NPN) or homeopathic medicine number (DIN-HM) and can be legally sold in Canada. This number indicates that the product meets specific criteria for safety and purity, not that it is effective for any indication.

Medicinal plants content varies naturally from plant to plant – just as fruits from the same package may vary in taste and texture. There is no standard to measure the active content of each plant. Thus, efficacy of natural products should be expected to vary from brand to brand as well as from bottle to bottle of the same brand.

For more information about the Natural Health Products Regulations, or to check if a product has been assessed, visit the Health Canada website at http://www.hc-sc.gc.ca/dhp-mps/prodnatur/index-eng.php.

Does it work?

There is evidence that black cohosh effectively relieves the symptoms of menopause, dysmenorrhea and premenstrual discomfort.

• Dysmenorrhea;
  Premenstrual discomfort and menopause symptoms:
  The recommended dose is 40 to 80 mg daily of a standardized extract.

There is insufficient reliable information to conclude that black cohosh is effective in any other indication.

Is it safe?

• Black cohosh is not associated with any severe immediate toxicity, but some people may experience occasional stomachache, nausea and vomiting, headache, dizziness, feeling of heaviness in the legs or weight gain. Because the long-term safety profile of black cohosh is not known, most experts recommend limiting its use to less than 6 months. There is no known allergy associated with black cohosh.

  During fall 2006, Health Canada has warned Canadians about a possible link between liver damage and consumption of herbal products containing black cohosh. Definite link has not been established and reported cases are rare. Caution is advised.

• Preliminary research suggests that animals that get black cohosh and eventually get cancer, have more aggressive tumors.
• Black cohosh is contraindicated in pregnant and lactating women. There have been reports of spontaneous abortions due to the ingestion of large amounts of black cohosh. Because of the estrogenic effect of the plant , it should not be used by pregnant or lactating women. However, it is safe when used in pregnant women at term, but it should be used with the supervision of a health care professional.

Clinical notes

• Black cohosh has interesting properties and a low risk of short-term toxicity. But because its long term safety profile is not documented, it should not be used for more than 6 months.
• Do not confuse black cohosh with blue cohosh and white cohosh. These plants do not have the same properties.

References

1. Blumethal M et al. The Complete German Commission E monographs, 1998
2. Natural Medicines Comprehensive Database, Therapeutic Research Faculty, 2007
3. Lininger S. et Al. The Natural Pharmacy, Prima Health, 1998
4. Peirce, Andrea. Practical Guide to Natural Medicines, APha, 1999
5. Facts & Comparisons, The Lawrence review of natural products, 1998
6. Passeportsanté.net. Actée à grappes noires. http://www.passeportsante.net
7. Barnes J. et Al. Herbal Medicines, 2nd edition, Pharmaceutical Press, 2002
8. Herbal Companion to AHFS DI, American Society of Health-System Pharmacists, 2001
9. Taylor J. CE: Phytomedicinals: Uses, precautions, and drug interactions. Drug Topics 2003;1:79
10. Kligler B. Black Cohosh, American Family Physician, 2003;68:114-6