Blue Cohosh Side Effects and Warnings

Safety Issues

There are many serious safety concerns with blue cohosh.

Some of the compounds found in blue cohosh, such as caulophyllosaponin, methylcytosine, and caulosaponin, appear to constrict coronary vessels, limiting blood flow to the heart and reducing its ability to pump. ¹ One published case report documents profound heart failure in a child born to a mother who used blue cohosh to induce labor. ² Severe medical consequences were seen in another child as well. ³ Other blue cohosh constituents are known to interfere with the ability of a newly fertilized ovum to implant in the uterus, damage the uterus and thyroid, and cause severe birth defects in cattle and laboratory rats. ⁴ Given these reports, the availability of safe alternatives for stimulating labor, and the lack of studies to document the herb's efficacy and safety, NAT strongly advises against using blue cohosh.