Black cohosh is a medicinal plant native from eastern North America. Known for its anti-inflammatory, sedative, and pain-relieving properties, black cohosh has the potential to reduce common menopause symptoms. Read further to know more about the benefits and side effects of black cohosh.
What is Black Cohosh?
Scientific name: Actaea racemosa
Common names: Baneberry, black cohosh, black snakeroot, bugbane, cimicifuga, rattleroot, rattleweed, rattletop, traubensilberberze, squawroot, and wanzenkraut.
Actaea racemosa, also known as black cohosh, is a medicinal plant from the Ranunculaceae family, and native from Eastern North America. Before the arrival of the Europeans, Native Americans used black cohosh to relieve various disorders including several conditions unique to women such as menopause and amenorrhea [1, 2].
Black cohosh became an official drug in the United States Pharmacopeia in 1820. Yet, black cohosh grew in popularity in 1844 when Dr. John King, an eclectic physician, published its use as a treatment for a variety of conditions including chronical ovaritis, endometriosis, and menstrual derangements .
The key medical components in black cohosh include triterpene glycosides, phenolic acids, flavonoids, volatile oils, and tannins.
- Actein is found in the roots of black cohosh and can inhibit the growth of breast tumors, giving black cohosh anti-cancer effects .
- 23-epi-26-deoxyactein is similar to actein, and this compound is a triterpene glycoside that can be extracted from black cohosh roots. It can also suppress the growth of breast cancer cells .
- Cimicifugosidase is obtained from black cohosh roots and also acts as an anti-cancer agent .
Currently, more than 20 polyphenolic derivatives have been found in the roots of black cohosh, including caffeic acid, isoferulic acid, fukinolic acid, and cimicifugic acids. These compounds have anti-inflammatory and antioxidant properties [7, 8].
Also known as essential oils, volatile oils are insoluble in water and come from a variety of plants. Volatile oils may be helpful in the prevention and treatment of a variety of cancers, including leukemia, and mouth, breast, lung, prostate, liver, colon, and brain cancer .
Tannins are polyphenolic compounds present in many plant foods. Tannins have anti-cancer, antioxidant, and antimicrobial properties .
Mechanism of Action
Although several clinical studies have shown the effectiveness of black cohosh extract in treating menopausal symptoms, its mechanism of action is still unknown .
One proposition states that black cohosh extract may act as a selective estrogen receptor modulator, meaning that it may “simulate” the normal activity of estrogen. Yet, several studies have shown that black cohosh extract does not have any estrogenic effects [12, 13].
Another theory proposes that the effects of black cohosh derive from its antioxidant properties. However, a study using fish did not detect antioxidant properties from black cohosh .
Health Benefits of Black Cohosh
1) Black Cohosh May Improve Menopausal Symptoms
In one study (DB-RCT) of 84 postmenopausal women, black cohosh tablets decreased hot flashes, compared to placebo .
In another DB-RCT study, 48 postmenopausal women with sleep disturbances received a daily dose of either black cohosh or placebo during a 6-month period. The results showed that, compared to placebo, black cohosh improved the sleep quality of postmenopausal women .
Despite the supporting evidence that black cohosh can treat menopausal symptoms, a DB-RCT study of 132 patients receiving a daily tablet of either black cohosh or placebo found that there was no difference between the effects of black cohosh and the placebo .
Another study (meta-analysis) reviewed 16 different studies (RCT) to test the effectiveness of black cohosh for treating menopausal symptoms. The main conclusion of the study was that there was no insufficient evidence to prove that black cohosh is an effective alternative to treat menopausal symptoms .
However, the meta-analysis remarked the overall poor quality of the studies and states that further studies need to be conducted in this matter to provide a concise answer .
2) Black Cohosh May Enhance Fertility
In one study (RCT), a group of 119 infertile people that took clomiphene citrate (a drug used to treat infertility in women) was divided into two. Both groups received clomiphene citrate for 4 days, while one of the groups received a supplement of black cohosh for 12 days. It was concluded that adding black cohosh to clomiphene citrate improved pregnancy rate .
Polycystic Ovary Syndrome (PCOS) is a set of symptoms caused by the strong presence of male hormones in females. It affects approximately 17.8% of women in reproductive age. These symptoms may include irregular menstrual cycles, hirsutism, acne, and infertility .
A systematic review involving 33 studies analyzed the effect of 6 plants including black cohosh on women with PCOS. In this review, it was concluded that black cohosh may increase ovulation and improve fertility .
3) Black Cohosh May Treat Uterine Fibroids
A uterine fibroid is a non-cancerous tumor in the uterus that may lead to painful periods [R].
One study (DB-RCT) enrolled 244 patients with menopausal symptoms. Half of the patients were treated with 2.5 mg of tibolone per day (a steroid used in the treatment of endometriosis), while the other half was treated with 40 mg of black cohosh extract per day. The results showed that black cohosh extract is more effective against uterine fibroids than tibolone .
4) Black Cohosh May Aid Diabetes Treatment
In an animal study, black cohosh extract was administered orally and by injection to 68 mice over a span of 7 days. The results indicated that black cohosh extract may treat type 2 diabetes, but more studies are needed to determine the efficiency of black cohosh in humans .
5) Black Cohosh May Improve Bone Health
In a cell-based study, a black cohosh component (25-acetylcimigenol xylopyranoside) reduced the activity of bone-loss agents significantly .
In an animal-based study, black cohosh extract was administered intravenously on rats in different doses. The results of the study showed that unknown substances in black cohosh extract reduced bone mass loss .
6) Black Cohosh Has Anti-Cancer Effects
In another lab study, black cohosh root extract was administered to human breast cancer cells. The results indicated that three specific components of black cohosh extract (action, 23-epi-26-deoxyactein, and cimicamerosidase A) inhibited the growth of breast cancer cells .
7) Black Cohosh May Treat AIDS
In a cell-based study, 83 chemicals from different plants were evaluated for anti-HIV activity. Of these chemicals, actein (a key component of black cohosh extract) elicited a strong response against HIV/AIDS .
8) Black Cohosh May Promote Weight Loss
One study analyzed the effect of black cohosh extract on 9 mice and compared them with a larger group of 18 mice. The results found that mice treated with black cohosh extract over a period of 6 weeks gained less weight and had notable fat accumulation compared to the other mice .
9) Black Cohosh May Reduce Anxiety
Black Cohosh May Cause Liver Damage
A 44-year old woman that used black cohosh for a month developed liver damage. Since the woman was not taking any other drugs, it was concluded that liver injury was caused by the use of black cohosh .
Black Cohosh May Increase the Development of Breast Cancer
In one study, 150 mice with breast cancer received 0.3 mg/day of black cohosh extract. The results of the experiment showed that black cohosh increased the spread of cancer cells (metastasis) from existing tumors .
Black Cohosh May Cause Several Mild Side Effects
A systematic review of 13 clinical trials, 3 postmarketing surveillance studies, 4 case series, and 8 single file reports found that the use of black cohosh by the general public is safe. However, several mild side effects were linked to black cohosh, including upset stomach, rashes, headaches, dizziness, and breast pain .
Limitations and Caveats
- Contradicting studies. There are several studies that support the use of black cohosh extract to treat common menopausal symptoms, but there are also several studies that show the opposite effects. There has not been a final verdict about the use of black cohosh for the treatment of menopausal symptoms [17, 18, 35, 19, 20].
- Poor quality RCT studies. Despite a large number of studies on the use of black cohosh extract to treat menopausal symptoms, many RCT studies lacked quality and clearness. Many studies showed incomplete data outcome, poor reporting, statistical insignificance, unclearness, and vague conclusions .
- Lack of human studies. Although there is a large number of human studies trying to prove or disprove the use of black cohosh to treat menopausal symptoms, there are hardly any concrete human studies aimed to prove or disprove any other benefits or side effects listed above [33, 31, 30, 29].
- Tamoxifen (Nolvadex): A cell-based study showed that using black cohosh and tamoxifen at the same time might reduce the effectiveness of this drug .
- Atorvastatin (Lipitor): A case study of a 53-year-old woman taking black cohosh and atorvastatin simultaneously found that the combination resulted in a dangerous increase in liver enzymes that may indicate liver damage .
- Cancer drugs: In a cell-based study, the interaction between black cohosh and common drugs used in cancer therapy was tested. The results showed that black cohosh increased the toxicity of doxorubicin (Adriamycin) and docetaxel (Taxotere) on cancer cells. However, black cohosh also decreased the efficiency of cisplatin on cancer cells .
- Drugs are broken down by the liver: Black cohosh inhibits the activity of cytochrome P450 (CYP450) enzymes, which break down several drugs. The inhibition of these enzymes may lead to liver damage [39, 40].
Natural Sources (or Forms of Supplementation)
The most common method of taking black cohosh is by tablets. However, black cohosh is also available in capsules, liquid tinctures, and extracts that can be mixed in water and dried root for tea [41, 42, 43].
There is no standardized dose for the use of black cohosh, but a dose of 40 mg/day is commonly used in studies for a variable period of time, depending on the metabolism of the patient and the severity of the symptoms .
In several studies, women have used black cohosh at a dose of 160 mg/day without any visible side effects. However, it is recommended to consult a doctor before using the product .
“Since I started using black cohosh, hot flashes have stopped, and I now have a better sleep quality “
“I was having hot flashes 4 to 6 times a day. Black cohosh completely eliminated them within a week.”
“I had to stop taking black cohosh because my lymph nodes were swelling in my neck. Ever since I stopped taking the product, the swelling has decreased.”
“I bought black cohosh for my post-menopausal mother. She says that black cohosh has not helped her with hormonal changes.”