- Black snakeroot
- rattlesnake root
For Patients & Caregivers
Tell your healthcare providers about any dietary supplements you’re taking, such as herbs, vitamins, minerals, and natural or home remedies. This will help them manage your care and keep you safe.
What is it?
Black cohosh is a plant used in herbal medicine. The root of this plant is used to treat menstrual (monthly period) cramps and symptoms you may get during menopause (permanent end to your menstrual cycle), such as hot flashes.
You can take black cohosh supplements as tablets, capsules, or liquid extracts.
What is it used for?
Black cohosh is used to:
- Treat menstrual cramps
- Treat symptoms of menopause such as hot flashes
Black cohosh also has other uses that haven’t been studied by doctors to see if they work.
Talk with your healthcare provider before taking black cohosh supplements. Herbal supplements can interact with some medications and affect how they work. For more information, read the “What else do I need to know?” section of this resource.
What are the side effects?
What else do I need to know?
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 (2) (3), or in combination with other herbs (4) (5), is effective in the treatment of menopausal symptoms, although data are conflicting (6) (31) (32) (36) (45). Conclusions of a meta analysis cite insufficient evidence to support use for menopausal symptoms (40).
Investigations of black cohosh for treating hot flashes, due to breast cancer treatment, yielded mixed results (10) (11) (12). But supplementation was found effective in treating menopausal syndrome induced by luteinizing hormone-releasing hormone analogue (LHRH-a) (57). In other studies, black cohosh did not enhance bone density, improve menopausal symptoms nor improve the 10-year risk of coronary heart disease in early postmenopausal women (37), although it has been 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.
Preclinical findings indicate that black cohosh decreased proliferation of prostate cancer cells (14) and induced 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).
Concomitant use of black cohosh with prescription medications has been associated with adverse drug reactions, most commonly involving abnormal hepatic function, hepatitis or hepatotoxicity (58). Black cohosh should not be confused with blue cohosh, which has a different medicinal profile. It is also not clear whether or not black cohosh acts as a phytoestrogen. Patients with breast cancer or at risk of breast cancer should consult with their physicians before taking it.
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).
In other studies, 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).
- 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).
- Severe hyponatremia was reported in a 39-year-old woman following consumption of several doses of black cohosh to induce and augment labor for giving birth at home. She later underwent cesarean delivery, and her sodium levels returned to normalcy after being treated with hypertonic saline (59).
- Acute onset mania associated with black cohosh use has been reported in a patient, likely due to the herb’s psychopharmacological activities on serotonergic and dopaminergic receptors (61).
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). Clinical signficance has yet to be determined.
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).