Blue and Black Cohosh

The Difference Between Black Cohosh (Actaea racemosa) and Blue Cohosh (Caulophyllum thalictroides).

Both black and blue cohosh share a similar common name, American Indian heritage and their roots have historically been used to treat women's health conditions however the similarities end there. In fact the two herbs, which bear little physical similarity to one another, do not even come from the same genus and family of plants. According to the American Herbal Pharmacopoeia (AHP) blue cohosh monograph “these are taxonomically unrelated plants that are not typically confused.” Previously known as Cimicifuga racemosa, black cohosh is from the Ranunculaceae, or buttercup, family making it a cousin of pulsatilla (Anemone pulsatilla) which it has similarities to and can be substituted for. It is a tall hardy wildflower which has long, wand-like white flowers. Blue cohosh is from the Berberidaceae, or barberry family. The plant has dark blue berries and small, white flowers. According to Lloyd and Lloyd (1931), ‘cohosh’ is an Algonquin Indian word meaning ‘it is rough’ (with hairs).

Black cohosh is considered ‘the menopause herb’ however it also has a long history of being used for the nervous system. While it is useful for stressed menopausal women its anodyne and sedative properties can help nerve and muscle pain. Black cohosh is effective in relieving headaches, tinnitus, menstrual cramps and symptoms brought about by hormonal imbalances.

Blue cohosh is generally classed as a uterine tonic. Historically it was used to prepare the uterus for labour (partus praeparator), for period pain and for various ‘inflammations’ of the uterus. It is used most commonly in pregnancy and gynaecology, most specifically as a way to avoid conventional methods of induction. Case reports of adverse events in recent years, however, have called for an evaluation of the plant’s pharmacological and safety data. The AHP monograph says ”it may still prove to be a safe and effective induction agent when used by highly trained and experienced birthing professionals, but concern regarding potential toxicity has limited its use in birthing.” A review of the data suggests that blue cohosh is indeed associated with certain adverse events reported, but confounding factors make it impossible to establish a causal relationship. The monograph stressed the “need to use the herb within the context of those most experienced with it and in the context of how it was most widely used traditionally, in combination with other botanicals.” A combination of blue and black cohosh has been shown to be effective in ripening the uterus for augmenting labour. There were claims of neurological toxicity in a newborn after using this combination however they were formally disputed on the grounds that the toxic effects suggested would only occur if much higher doses than reported were consumed. Caution is therefore advised with this herb during pregnancy.

References

Blue Cohosh Root & Rhizome monograph. American Herbal Pharmacopoeia. 2012.

HEC black cohosh monograph

Smith T. American Herbal Pharmacopoeia Publishes Blue Cohosh Monograph. HerbalGram Winter 2012;96:18. https://www.herbalgram.org/resources/herbalgram/issues/96/table-of-contents/hg96-orgnews-blkcohosh/

Trickey R. Women, Hormones and the Menstrual Cycle. 3rd edn. Fairfield: Melbourne Holistic Health Group. 2011. p. 293