- Black snakeroot
- rattlesnake root
For Patients & Caregivers
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.
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.
Clinical trial results are mixed.
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.
- 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.
For Healthcare Professionals
Obtained from root of the plant, black cohosh is used as a dietary supplement to relieve symptoms of menopause and dysmenorrhea. It has antiosteoporotic effects (8) and enhances bone formation (9). Clinical studies indicate that black cohosh by itself, (1) (2) (3) or in combination with other herbs (4), (5) is effective in the treatment of menopausal symptoms, but data are conflicting (6) (31) (32) (36) (45). Conclusions of a meta analysis indicate insufficient evidence to support use for menopausal symptoms (40).
Investigations of black cohosh for treating hot flashes, due to breast cancer treatment, also yielded mixed results (10) (11) (12). In other studies, supplementation did not enhance bone density, improve menopausal symptoms, or the 10-year risk of coronary heart disease in early postmenopausal women (37), but was reported to improve sleep (53). A black cohosh extract demonstrated anti-diabetic potential in a murine model (46). Human studies have yet to be conducted.
Black cohosh has also been evaluated for potential anticancer effects. Preclinical findings indicate that it decreases prostate cancer cell proliferation (14) and induces an apoptotic response in liver cells (21). However, it also increased the incidence of metastatic disease in mice (16). Whether it has similar effects in breast cancer patients is not clear, although a retrospective observational study of breast cancer patients found that black cohosh enhanced disease-free survival (15).
Hepatoxicity has been associated with use of black cohosh (34), but data are conflicting (39).
Mechanism of Action
Black cohosh relieves menopausal symptoms likely by mimicking neurostransmitters: dopaminergic, noradrenergic, serotoninergic and GABAergic effects have been demonstrated (49). It was believed to have estrogenic effects due to its ability to relieve menopausal symptoms in women (40). However, studies show that it has no effect on the levels of LH, FSH, prolactin, or estradiol (24). A black cohosh extract was shown to have antiproliferative and antiestrogenic effects in ER-negative cells, which suggests that such effects are mediated via an estrogen-independent pathway (25), possibly through HER-2 signaling (26).
Black cohosh repressed the expression of cyclin D1 and ID3, and inhibited proliferation of HepG2, p53 positive, liver cells (43). In prostate cancer cells, it demonstrated antiproliferative effects, via impaired equilibrative nucleoside transporter (ENT) activity, resulting in hindered nucleoside uptake (50). Black cohosh was also reported to induce apoptosis and suppress estradiol-induced cell proliferation in human endometrial adenocarcinoma cells (55).
Hepatotoxicity is a major concern with black cohosh use. Evaluation of liver biopsies from two patients who took black cohosh supplements showed the pattern of pathological injury of liver cells to be identical to toxic necrosis, seen during autoimmune hepatitis (51).
- Black cohosh should not be confused with blue cohosh.
- Whether black cohosh possesses estrogenic activity is still not clear. This product should be used under the supervision of a physician.
- After reviewing 30 independent cases of reported hepatoxicity associated with black cohosh intake, the United States Pharmacopeia’s Botanical Expert Committee decided that black cohosh products should include a statement of caution concerning their use (28).
- A recent survey reported poor quality control of several black cohosh products (44).
- Gastrointestinal upset and rashes are most common followed by dizziness, headaches, nausea, and vomiting when higher than normal doses are taken (27)
- Hepatotoxicity has been reported following use of black cohosh (18) (20) (33) (34) (47).
- Two cases of liver injury resembling autoimmune hepatitis were reported after taking black cohosh. Both patients responded to treatment with corticosteroids (35).
- A case of coagulation activation, fluid retention, and transient autoimmune hepatitis has been reported associated with use of black cohosh (38).
- Bradycardia was observed in a woman following use of black cohosh (41).
- 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 (48).
Tamoxifen: Black cohosh may interfere with the action of tamoxifen (42). Clinical relevance is not known.
Chemotherapy drugs: Black cohosh may increase the toxicity of doxorubicin and docetaxel (13). Clinical signficance has yet to be determined.
Cytochrome P450 3A4: Black cohosh may interact with drugs that are metabolized by CYP3A4 enzyme (17).
Simvastatin: Black cohosh and actein (a compound isolated from black cohosh) have synergistic effects with simvastatin, resulting in enhanced activity. But there is also potential for increased side effects (56).