Black Cohosh

Which black cohosh preparations are used?

Clinical products are mostly dry extracts made with water and alcohol. The EU monograph covers three: an ethanol 58% extract (5.6 mg dry extract per day), an ethanol 60% extract (6.5 mg per day) and an isopropanol 40% extract (5 mg per day). The isopropanolic dose corresponds to about 40 mg of root per day. 1 2

Trials have also used other products, such as an ethanol extract standardized to 2.5% triterpene glycosides at 160 mg per day in the HALT trial. A study comparing about 40 mg and 127 mg per day found similar effects. 3 4

Quality problems: wrong plant and unlisted herbs

Some black cohosh products have contained the wrong herb or mixtures with herbs not listed on the label. Adulteration with Asian Actaea species is considered the most plausible cause of the reported liver problems, though this is not proven. 3 8

Adulteration can be detected with methods such as microscopy, thin-layer chromatography and DNA barcoding. 3

In the EU, black cohosh is available as a licensed herbal medicine with a defined extract and dose. Licensed products state the extract type and amount, which supplements do not have to do in the same way. 1 6

Black cohosh is not blue cohosh

Blue cohosh (Caulophyllum thalictroides) is a different plant. It may raise blood pressure and blood sugar and cause chest pain, and its use to induce labor has been linked to life-threatening complications in infants. 8