Black Cohosh
Black Cohosh
This information describes the common uses of Black Cohosh, how it works, and its possible side effects.

Common Name

Black snakeroot, rattlesnake root, squawroot

How It Works

There is some evidence that black cohosh is effective for menopausal symptoms. More research is needed.

It is not clear if black cohosh is beneficial for menopausal symptoms due to conflicting results from various studies. There is not enough evidence to support its anticancer effects in humans. Patients should use caution because liver toxicity has been reported from use of black cohosh.

Purported Uses

  • Menopausal symptoms
    A few studies showed that black cohosh may help relieve menopausal symptoms.
  • To ease painful or heavy menstruation
    Clinical trials have not evaluated this use.
  • Premenstrual syndrome (PMS)
    There are no clinical data to support use of black cohosh for PMS.
  • As a sedative
    There are no data to back this claim.
  • Hot flashes
    Clinical trial results are mixed.

Patient Warnings

  • Black cohosh should not be confused with blue cohosh.

Do Not Take If

  • You are taking Tamoxifen: Black cohosh may interfere with the action of tamoxifen, but clinical relevance is not known.
  • You are taking Chemotherapy drugs: Black cohosh may increase the toxicity of doxorubicin and docetaxel. Clinical signficance has yet to be determined.
  • You are taking drugs that are substrates of Cytochrome P450 3A4: Black cohosh may increase the side effects of these drugs.
  • You are taking Simvastatin: Black cohosh and actein (a compound isolated from black cohosh) have synergistic effects with simvastatin, resulting in increased activity. But there is also potential for increased side effects.

Side Effects

  • Stomach upset
  • Liver failure
  • Hepatotoxicity (liver toxicity) has been reported following use of black cohosh.
  • Two cases of liver injury resembling autoimmune hepatitis were reported after taking black cohosh. Both patients responded to treatment with corticosteroids.
  • A case of coagulation activation, fluid retention, and transient autoimmune hepatitis has been reported associated with use of black cohosh.
  • Bradycardia (slowing of heart beat) was observed in a woman taking black cohosh.
  • Orobuccolingual dyskinesia (OBLD), involving interference with speech, tongue-biting, and eating difficulties, has been reported in a 46-year-old woman while taking a herbal supplement containing black cohosh and ginseng.

Special Point

Because it is still unclear whether black cohosh has estrogenic effects, women with estrogen receptor-positive (ER+) cancers should avoid this supplement.