Black Cohosh in pregnancy and breastfeeding

What NCCIH says about safety

While black cohosh has been used safely in research studies that lasted as long as a year and is generally well tolerated, concerns have been raised that it may cause liver damage in some people. Cases of liver damage—some very serious—have been reported in people taking products labeled as black cohosh. These problems are rare, and it’s uncertain whether black cohosh was responsible for them. If you take black cohosh, consult your health care provider if you develop symptoms of liver damage such as dark urine and fatigue. Some commercial black cohosh products have been found to contain the wrong herb or to contain mixtures of black cohosh and other herbs that are not listed on the label. It is possible but not proven that these contaminants might be responsible for cases of liver damage linked to black cohosh products. Black cohosh and blue cohosh (Caulophyllum thalictroides) are different herbs. Blue cohosh may cause adverse effects such as high blood pressure, high blood sugar, and chest pain. The use of blue cohosh to induce labor has been associated with life-threatening complications in the infant, including seizures. It’s uncertain whether black cohosh is safe for women who have had hormone-sensitive conditions such as breast or uterine cancer. If you take any type of medicine, talk with your health care provider before using black cohosh or other herbal products; some herbs and medicines interact in harmful ways. Black cohosh may not be safe for use during pregnancy or while breastfeeding.

Quoted in full from NCCIH so nothing is lost in summarising. Where they say “little is known”, that means the studies do not exist — not that the herb is known to be safe, and not that it is known to be harmful.

How much is actually known

A substantial number of studies in people have evaluated black cohosh for menopause symptoms. Much less research has been done on black cohosh for other conditions.

What the research has found

A 2023 review of 22 studies of products containing black cohosh extracts, alone or in combination with other herbs, found that they were potentially beneficial for overall menopause symptoms. Data on specific symptoms showed improvements in hot flashes but not anxiety or depressive symptoms. It’s uncertain whether black cohosh can reduce hot flashes related to breast cancer treatment. There aren’t enough reliable data to show whether black cohosh is effective for other uses.

Before you take this

Dose and form change the answer completely. A culinary amount of a spice, a cup of tea, and a concentrated supplement extract are three different things, and most research is done on the last of them.

Supplements are also not regulated like medicines, so strength and purity vary between products. Bring the actual bottle to your midwife, doctor or pharmacist — that conversation is worth more than any page, including this one.