Black Cohosh

📜 Historical Use

Black cohosh is a perennial buttercup-family plant native to eastern North America, carrying an unusually long list of older names — black snakeroot, macrotys, bugbane, bugwort, rattleroot, rattleweed, rheumatism weed, rattlesnake root. Native Americans used the root and rhizome for musculoskeletal pain, fever, cough, pneumonia, sluggish labour and menstrual irregularities, and for kidney ailments, malaria, sore throat and rheumatism. European settlers took it up as a tonic to support women's reproductive health, and it has been used medicinally in Germany since the late 19th century. LactMed records that Native American women supposedly used it as a galactogogue, but files that as a historical claim with no data behind it. The modern indication has narrowed almost entirely to menopause — hot flashes and night sweats, vaginal dryness, palpitations, tinnitus, vertigo, sleep disturbance, nervousness and irritability — with secondary promotion for menstrual cramps, premenstrual syndrome and to induce labour. One naming caution belongs on every black cohosh page: black cohosh and blue cohosh (Caulophyllum thalictroides) are different herbs. Blue cohosh may cause high blood pressure, high blood sugar and chest pain, and its use to induce labour has been associated with life-threatening complications in the infant, including seizures.

📊 What the Research Shows

Menopausal symptoms are the only use with a real evidence base, and that evidence is contested. The two highest-quality randomised controlled trials were both negative. A 2006 trial gave 351 women aged 45–55 with hot flashes and night sweats 160 mg/day black cohosh (70% ethanolic extract standardised to 2.5% triterpene glycosides), a multibotanical, hormone therapy or placebo; at 3, 6 and 12 months the number and intensity of symptoms did not differ from placebo. A 2009 trial gave 88 perimenopausal and postmenopausal women having at least 35 hot flashes and night sweats a week either 128 mg/day black cohosh (75% ethanolic, 5.7% triterpene glycosides), red clover, hormone therapy or placebo; symptoms declined in every group including placebo, with no significant difference for black cohosh, which showed worse symptom intensity at 6 and 9 months. Secondary outcomes — insomnia, fatigue, depression, anxiety, sexual dysfunction — showed no significant differences at any timepoint. The 2012 Cochrane review of 16 trials in 2,027 women found insufficient evidence either to support or to oppose use for menopausal symptoms, and a 2016 meta-analysis of four trials in 511 women found no significant association with reduced vasomotor symptoms. Against that, NCCIH cites a 2023 review of 22 studies finding black cohosh products potentially beneficial for overall menopause symptoms, with improvement in hot flashes but not in anxiety or depressive symptoms. It is uncertain whether it reduces hot flashes related to breast cancer treatment, and there are not enough reliable data for any other use.

Take 20-40mg standardized black cohosh extract 2x daily.

Rare liver concerns. Do not use over 6 months. Avoid with liver disease.

⚠️ What happens if taken in excess:

Liver injury comes first here. NIH's LiverTox database assigns black cohosh a likelihood score of A: products sold as black cohosh are well established causes of clinically apparent liver injury, though the responsible ingredient is unclear. More than fifty instances have been reported, from symptomatic enzyme elevations without jaundice through acute hepatitis, prolonged hepatitis with cholestasis and autoimmune hepatitis, to acute liver failure requiring transplantation or ending in death; ODS counts at least 83 cases worldwide. Latency ran 1 to 48 weeks, usually 2 to 12; presentation was typically jaundice with a hepatocellular pattern. Two things cut the other way: prospective trials in more than 1,200 patients showed no enzyme elevations and no clinically apparent injury, and causality is disputed because several retrieved products contained Chinese Actaea species such as C. dahurica rather than A. racemosa. Australia has required a liver warning on labels since 2007 and the US Pharmacopeia recommended one in 2008; the FDA requires neither. Seek liver testing for dark urine, jaundice, abdominal pain or unexplained fatigue; USP advises that people with liver disorders avoid it entirely. Other adverse effects are mild and transient: gastrointestinal upset, rash, hypotension, bradycardia, central nervous system effects, nausea and vomiting. It may not be safe in pregnancy or breastfeeding: AHPA advises pregnant women avoid it except under provider supervision, and LactMed found no data in nursing mothers or infants. Whether it is safe for women who have had hormone-sensitive conditions such as breast or uterine cancer is uncertain.

The truthful headline is that there is very little here, and that the emptiness reflects absent research rather than demonstrated safety. ODS states that black cohosh is not known to have any clinically relevant interactions with medications, although this has not been systematically studied. Worth noting what is absent: black cohosh does not appear in NCCIH's December 2024 clinical digest on herb-drug interactions, which names Asian ginseng, cat's claw, chamomile, cranberry, ginkgo, goldenseal, green tea and St. John's wort. The contrast with St. John's wort is instructive — that herb is a potent inducer of both cytochrome P-450 enzymes and intestinal P-glycoprotein, with documented interactions with cyclosporine, indinavir, oral contraceptives, coumadin, digoxin and benzodiazepines. Black cohosh has no comparable catalogued profile. What the case literature shows is co-medication rather than interaction, and the distinction matters: reported liver-injury cases occurred in women also taking levothyroxine, simvastatin, irbesartan and insulin, and one involved a compounded mixture that also contained goldenseal, ginkgo, ground ivy and oat seed, where a herb-herb contribution could not be excluded. LiverTox found no evidence of cross-sensitivity for liver injury between black cohosh and conventional estrogen preparations or other herbals. Where injury carried autoimmune features or prolonged cholestasis, management has used prednisone with or without azathioprine. NCCIH's general caution still applies, most of all to drugs with a narrow therapeutic index such as warfarin, digoxin and chemotherapy agents: tell your prescriber what you are taking.

1. Black Cohosh: Usefulness and Safety — National Center for Complementary and Integrative Health NIH NCCIH (2024)[NIH ↗]
2. Black Cohosh — Fact Sheet for Health Professionals — Office of Dietary Supplements NIH Office of Dietary Supplements (2020)[NIH ↗]
3. Black Cohosh — National Institute of Diabetes and Digestive and Kidney Diseases LiverTox: Clinical and Research Information on Drug-Induced Liver Injury (2025)[NIH ↗]
4. Black Cohosh — National Institute of Child Health and Human Development Drugs and Lactation Database (LactMed) (2021)[NIH ↗]
5. Herb-Drug Interactions — National Center for Complementary and Integrative Health NCCIH Clinical Digest (2024)[NIH ↗]