Black Cohosh

Black cohosh (known as both Acetae racemosa and Cimicifuga racemosa) is a tall, flowering plant that is a member of the buttercup family of plants that is native to North America (1,2). Other common names include macrotys, rattleweed, rattleroot, black snakeroot, and bugwort (1,2). Black cohosh has been used traditionally in North American Indian medicine for hundreds of years for various ailments (1,2). Black cohosh has multiple constituents that demonstrate pharmacological activity such as isoferulic acids (anti-inflammatory properties), phytoestrogen (plant based estrogens), and glycosides (1,2). The roots of black cohosh have been used for gynecologic conditions (lactation promotion, menstruation promotion), joint pains, analgesia, malaria, sore throat, and labor pain relief (1,2). The Cherokee used an alcoholic based extract to treat rheumatism and black cohosh tea to treat colds, coughs, fatigue, tuberculosis, and as a sedative for babies (1,2). Recently, it has emerged as a popular natural product used to alleviate menopausal symptoms such as hot flashes, mood disturbances, and vaginal dryness (1,2). There are also some preliminary studies that suggest there may be a benefit in preventing or treating osteoporosis as well (1,2).

Summary of Evidence

A few controlled trials and case series have reported a benefit in using black cohosh to improve menopausal-like symptoms (2,3). However, these initial studies were suggestive and suffered from methodological weaknesses such as lacking a placebo control group, using an unspecified source of black cohosh, and having small sample sizes (≤30 participants per group) and short trial durations (≤12 weeks) (2,3) . The growing interest in the effect of black cohosh on menopausal symptoms has led to several well designed randomized controlled trials being conducted (2,3). One of which is the Herbal Alternatives for Menopause Trial (HALT), which was a 1 year randomized double-blind controlled trial that examined the short and long term effects of black cohosh 160 mg daily; (2) multibotanical (50 mg black cohosh, alfalfa, chaste tree, dong quai, false unicorn, licorice, oats, pomegranate, Siberian ginseng, boron) four capsules daily; (3) multibotanical plus telephone counseling to increase dietary soy; (4) conjugated equine estrogen 0.625 mg ± 2.5 mg medroxyprogesterone acetate; or (5) placebo on menopausal symptoms in 351 symptomatic perimenopausal or post menopausal women (3). Having a placebo control is critical in trials that use menopause symptoms as an endpoint for efficacy since these symptoms can regress naturally over time (3). ClimiPure was the black cohosh product that was used and contained A. racemosa standardized to 2.5% triterpene glycosides in a 70% ethanol extract (3). Consistency, purity and accuracy of the product was reinforced by quality assurance documents provided by the manufacturer PureWorld Inc., and independent testing of the products for the presence of labeled constituents, marker compounds, and contaminants (pesticides, heavy metals, and steroids) using high performance liquid chromatography, capillary electrophoresis, gas chromatography, and plasma mass spectroscopy by (3). The primary endpoint of this study was the reduction of menopausal symptoms, specifically the frequency and intensity of vasomotor symptoms per day and a reduction in the total Wiklund Menopause Symptom Scale score (3). The study found that there was no significant reduction in the severity, frequency of vasomotor symptoms and the Wiklund Menopause Symptom Scale score in the herbal interventions including black cohosh at the three, six, or 12 month intervals compared to placebo (3). However, the results of this study may not be applicable to all women because the subjects enrolled were highly selected (351 subjects enrolled of 3,443 who responded) and has on average six vasomotor symptoms per day, whereas most menopausal women and post menopausal women have much less frequent symptoms (3). A 2008 systematic review that excluded trials that did not focus on menopausal symptoms, did not use black cohosh monopreparations or did not use placebo for a control group and only included double blinded randomized controlled trials demonstrated that in 6 studies with a total of 1112 peri- and post menopausal women, there was no consistent effect of black cohosh on menopausal symptoms (4). However, a beneficial effect of black cohosh on peri-menopausal women cannot be excluded (4). Instead, the efficacy of black cohosh for treating menopausal symptoms is uncertain as the interpretation of these studies is complicated due to the fact that different amounts of the black cohosh from various sources were used and the primary outcome that was measured was different (4). In order to provide more definitive evidence on the effects of black cohosh on menopausal symptoms, a well designed long term randomized, placebo controlled trial representative of a typical menopausal patient that compares two arms (black cohosh vs. placebo) on the frequency of menopausal symptoms and quality of life scores is needed.

Mechanism of Action

The mechanism of action of black cohosh remains quite unclear (2,5). It is believed that the black cohosh rhizome has mild estrogenic binding effects due to the phytoestrogen component (formonoetin and tritepenoid 26-deoxyacetin) (2,5). However, samples from the roots and rhizomes from different black cohosh plants in 13 locations in the eastern United States did not contain any formononetin, which lead researchers to conclude that another compound may be responsible for the estrogen like activity (2,5). Recent reports suggest that there may be no direct effect on estrogen receptors (2,5). A report has suggested that black cohosh antagonized proliferative effects on cells that are induced by estriadol (2,5). Limited studies also suggested lower FSH levels in patients treated with black cohosh vs. placebo (N=110), but the baseline hormone levels were not known in each group (2,5). The present knowledge about the mechanism of action of black cohosh is conflicting and more investigation is needed to determine what the effects of black cohosh are in menopausal symptoms (2,5).

In addition to possible benefits in alleviating menopausal symptoms, recent preliminary in vitro and animal studies suggest that black cohosh may play a role in the treatment of osteoporosis (6,7,8). One study evaluated the possible selective estrogen receptor modulating effects of a black cohosh extract in rats and demonstrated that 3 months after an ovariectomy, control rats had lost more than 50% of the metaphyseal bone mass of the tibia, whereas, this was partially prevented in rats that were on black cohosh supplementation (7). It is believed that these effects are due to the inhibition of LH secretion and stimulated gene expression of IGF-I, collagen-1alpha1, osteoprotegrin and osteocalcin, which are all osteoblast products (7). Initial studies also demonstrated that an isopropanolic extract from the rhizomes of black cohosh (A. racemosa) enhances differentiation and increases the OPG-to-RANKL ratio of normal human osteoblasts, which may contribute to the positive skeletal effects of black cohosh (8,9). It has also been shown to suppress osteoclastogenesis (8). At this stage, black cohosh is not recommended for preventing or treating osteoporosis as the evidence is preliminary in nature and human studies on a wider scale are needed to provide definitive evidence on the benefits of black cohosh in osteoporosis (7).


With regards to the safety of using black cohosh, due to a lack of long term follow up, caution is advised until there is better quality safety data available (2,5). Black cohosh is likely safe when used up to six months in otherwise healthy, non-pregnant, non-lactating individuals (2,5). Native black cohosh contains small amounts of salicyclic acid, however, it is unknown how much is present in the standardized extracts that are available commercially (2,5). Thus, caution is advised in patients that are allergic to aspirin or other salicylates (2,5). It is not known whether the amount of salicyclic acid in the black cohosh will affect platelet aggregation or have other effects that are associated with salicylates (2,5). Black cohosh should also be avoided if the patient is allergic to black cohosh, its constituent, or other members of the buttercup or crowfoot family (2,5). Common side effects of black cohosh include nausea, vomiting, heaviness in the legs, indigestion, weight gain, headache, and hypotension at higher doses (2,5). Allergic skin reactions such as rashes have been reported after taking Remixin®, but these were deemed to be minor (2,5). Based on anecdotal reports, overdose of black cohosh may result in headache, nausea, vomiting, dizziness, bradycardia, visual disturbances, and perspiration (2,5). Black cohosh is contraindicated in individuals who have a history of estrogen dependent tumors, breast cancer, uterine cancer, endometriosis, or endometrial cancer (2,5). Black cohosh may have estrogenic activity and therefore may worsen such cancers (2,5). Black cohosh should also be cautioned in known seizure disorders, individuals with hypotension or taking antihypertensive medications (due to a theoretical risk of hypotension), individuals taking anticoagulants, and individuals on hormone replacement therapy especially tamoxifen or raloxifen (2,5). There have been a few cases of liver damaged that have been reported following use of black cohosh, however millions of people have taken the herb without apparent adverse health effects (2,5). Studies of black cohosh did not provide any scientific evidence to demonstrate that this herb causes liver damage; the United States Pharmacopoeia suggests that black cohosh may possibly cause liver damage and thus should be used with caution (2,5). If a patient has an active liver disorder or develops symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice, black cohosh should be discontinued immediately and medical help should be sought immediately (2,5). The safety of black cohosh use during pregnancy is not established and therefore not advised (2,5). It is contraindicated in pregnancy based on in vitro or animal studies that suggest black cohosh may have labor inducing effects, hormonal effects and anovulatory effects (2,5). The safety regarding the use of black cohosh during lactation has not been established and therefore it is not recommended (2,5). Tincture formulations of black cohosh during pregnancy are not recommended due to the high alcohol content (2,5).

Drug Interactions

The use of black cohosh has not been thoroughly tested with concomitant administration of other drugs or herbal products, and thus the following interactions are theoretical in nature (2,5). Black cohosh may interact with analgesics (additive analgesic effects), antidepressants, selective serotonin reuptake inhibitors (mechanism of black cohosh may be centrally mediated and may involve serotonin or dopamine receptors, thus additive antidepressant effects, and possibly toxicity and serotonin syndrome), antihistamines (black cohosh may inhibit histamine release), antihypertensives (additive hypotensive effect), estrogens (may have additive estrogenic effects), and tamoxifen, raloxifen (increased risk of endometrial hyperplasia from concomitant administration) (2,5).

Because of the lack of conclusive evidence on the role of alleviating menopausal symptoms and preventing osteoporosis, the use of black cohosh is not recommended at this point (2,5). However, patients may be adamant on taking black cohosh and therefore it is important to be knowledgeable on choosing the appropriate product for the patient (2,5). The dose of the black cohosh is based on the content of tritepenes, which is calculated as 26-deoxyacetein (2,5). The German product Remifemin® is used in the majority of the clinical studies and therefore this is the recommended product to order for the pharmacy (2,5). The preparation of the products can vary from manufacturer to manufacturer, as well as from batch to batch within a single manufacturer (2,5). Because the active components responsible for the effect on menopausal symptoms is unclear, the standardization may not be possible and the clinical effects of the other brands may not be comparable, so it is recommended to use the black cohosh product that has been studied the most in the alleviation of menopausal symptoms (2,5). Additionally, because of the widespread use of the Remifemin® product, its safety has been demonstrated on a short term basis of 6 months (2,5). Preparations of black cohosh are made from its roots and rhizomes (2,5). This product contains an alcoholic extract of black cohosh rhizome that is standardized to contain 1 mg of 26-deoxyacetein per 20 mg tablet (2,5). The black cohosh extract is equivalent to 20 mg of root per tablet (2,5). The current formulation of Ramifemin® is a tablet (root extracted with isopropyl alcohol, 40% by volume) (2,5). For the relief of menopausal symptoms, studies have used two 20 mg Remifemin® tablets (equivalent to 1-2 mg 27-deoxyacetin) twice daily for up to 12 weeks (2,5). Another study used one Remifemin® tablet which contained 2.5 mg isopropranolic extract of Cimicifuga racemosa that is equivalent to 20 mg root stock twice daily for 12 weeks (2,5). The onset of black cohosh’s action is thought to occur two weeks after treatment initiation, however, the HALT trial showed no benefit for up to 12 months (2,5). With regards to preventing osteoporosis, since the studies are rudimentary in nature and have not been tested in humans, a dose cannot be recommended. Patients should be advised not to take black cohosh for preventing osteoporosis (2,5).

Counseling Points

With regards to counseling points for patients considering the use of black cohosh for treating menopausal symptoms, it is important to address the misconceptions that may be influenced by the marketing claims by the manufacturers (2,5). Plant derived estrogens are not a natural or safer alternative for hormones for women with menopausal symptoms (2,5). Currently, there is no convincing evidence that these phyotestrogens help reduce hot flashes or night sweats (2,5). Current clinical trials have shown that the use of black cohosh is not more effective than placebo over a 12 month period (2,5). It is not known if there is any benefit after 12 months of use (2,5). For this reason, black cohosh is not recommended for hot flashes or other menopausal symptoms (2,5). Patients may be adamant on taking black cohosh and it is important to address any safety concerns that patients need to be aware of before taking black cohosh (2,5). Patients that have a history of breast cancer should avoid taking black cohosh as it may stimulate the breast tissue and encourage tumor growth (2,5). If patients are allergic to aspirin or salicyclic acid, they should not take black cohosh as salicyclic acid is present in this compound (2,5). Patients who are allergy to any plants from the buttercup family or have a known allergy to black cohosh should not take this herbal product as well (2,5). Side effects that are common with black cohosh are nausea, vomiting, heaviness in the legs, indigestion, weight gain, headache, and hypotension (2,5). Patients who have known seizure disorders or who are taking antihypertensive medications should avoid taking this natural health product (2,5). Although there are reports of liver damage from taking black cohosh, studies did not demonstrate that black cohosh may be responsible for causing such liver damage (2,5). The safety of black cohosh during pregnancy and lactation are not established and therefore should be avoided. Tincture formulations are not recommended during pregnancy due to the high alcohol content (2,5). Patients that are taking antidepressants, antihypertensives, and estrogens (tamoxifen, raloxifen) should avoid taking black cohosh (2,5). If the patient does not have any of the above mentioned precautions, then a suggested dose and product to try is Remifemin® one to two 20 mg tablets daily for up to 12 weeks (2,5). This is the dose that is used in the clinical studies (2,5). Furthermore, this formulation has been used in the majority of the clinical trials and the short term safety (6 months) has been established (2,5). If the patient reports no improvement at all after 12 weeks, Remifemin® should be discontinued (2,5). Other measures that can help with relieving menopausal symptoms includes reduction of caffeine intake, smoking cessation, exercising, and reducing core body temperature (dressing in layers, using a fan, and consuming cold drinks). Black cohosh should not be taken for the goal of preventing osteoporosis as there is no evidence in humans that suggest a benefit (2,5). Thus patients should be advised not to take it for this particular goal (2,5).


  1. Lieberman S, “A Review of the Effectiveness of Cimicifuga racemosa (Black Cohosh) for the Symptoms of Menopause,” J Womens Health, 1998, 7(5):525-9.
  2. Natural Standard. Natural Standard - Black cohosh [Internet]. Black cohosh (Cimicifuga racemosa [L.] Nutt.). 2012 [cited 2012 Mar 22]. Available from:
  3. Newton KM, Reed SD, LaCroix AZ, Grothaus LC, Ehrlich K, Guiltinan J. Treatment of vasomotor symptoms of menopause with black cohosh, multibotanicals, soy, hormone therapy, or placebo: a randomized trial. Ann. Intern. Med. 2006 Dec 19;145(12):869–79.
  4. Borrelli F, Ernst E. Black cohosh (Cimicifuga racemosa) for menopausal symptoms: A systematic review of its efficacy. Pharmacological Research. 2008 Jul;58(1):8–14.
  5. McKenna DJ, Jones K, Humphrey S, Hughes K. Black cohosh: efficacy, safety, and use in clinical and preclinical applications. Altern Ther Health Med. 2001 Jun;7(3):93–100.
  6. Nisslein T, Freudenstein J. Effects of an isopropanolic extract of Cimicifuga racemosa on urinary crosslinks and other parameters of bone quality in an ovariectomized rat model of osteoporosis. J. Bone Miner. Metab. 2003;21(6):370–6.
  7. Viereck V, Gründker C, Friess SC, Frosch K-H, Raddatz D, Schoppet M, et al. Isopropanolic extract of black cohosh stimulates osteoprotegerin production by human osteoblasts. J. Bone Miner. Res. 2005 Nov;20(11):2036–43.
  8. Seidlova-Wuttke D, Hesse O, Jarry H, Christoffel V, Spengler B, Becker T, et al. Evidence for selective estrogen receptor modulator activity in a black cohosh (Cimicifuga racemosa) extract: comparison with estradiol-17beta. Eur. J. Endocrinol. 2003 Oct;149(4):351–62.


This information is presented for informational purposes only and is not meant to be a substitute for advice provided by qualified health care professionals. You should contact your qualified health care provider if you have or suspect any health problems. This article is not intended to provide medical advice for its readers

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