Black cohoshBotanical

• Hot flashes and night sweatsPossibly helps

  This is why almost anyone takes it, and the trial record is genuinely split.
  
  The 2012 Cochrane review of 16 RCTs (2,027 women) found insufficient evidence either to support or oppose its use [4].
  
  A 2016 systematic review and meta-analysis of 4 trials (511 women) found no significant association with reduced vasomotor symptoms [2].
  
  A 2006 RCT in 351 women compared 160 mg/day against placebo and found no difference in hot flash frequency or intensity at 3, 6, and 12 months [2].
  
  Against those, a 2023 review of 22 studies of black cohosh products reported potential benefit overall, with improvement in hot flashes specifically [3]. ^[4]

• Anxiety and depressive symptoms in menopausePossibly helps

  The same 2023 review that saw hot flash improvement found none for anxiety or depressive symptoms [3].
  
  That is one review's null result, not a body of evidence. Read it as unresolved [3]. ^[3]

• Hot flashes during breast cancer therapyPossibly helps

  NCCIH states it is uncertain whether black cohosh reduces hot flashes related to breast cancer therapy [3].
  
  That population gets studied separately for good reason, and the answer is not in yet [3]. ^[3]

• Menstrual cramps and PMS (traditional use)Possibly helps

  Traditional use covers menstrual cramps and PMS alongside menopausal complaints [15].
  
  No modern trial evidence is cited for those uses, and the FDA has approved black cohosh for nothing [15]. ^[15]

• Guideline bodies and NCCIH read the same evidence differentlyPossibly helps

  A live disagreement, left visible rather than settled.
  
  ACOG's 2015 guidelines concluded the data do not show herbal supplements like black cohosh are efficacious for vasomotor symptoms [2].
  
  The North American Menopause Society likewise calls benefit unlikely [2]. NCCIH's more recent framing is less dismissive, citing the 2023 review's potential benefit for hot flashes [3]. ^[2]

• Isopropanolic standardized extract (Remifemin)The most-studied product by a wide margin, and what most trial results actually describe

  Elemental content

  Two tablets a day, equivalent to 40 mg of root and rhizome [2]

  Absorption

  Not characterized — the compounds responsible for any effect are unknown [2]

  Best for

  The most-studied product by a wide margin, and what most trial results actually describe [2]

• Other dried-extract capsules and tabletsWidely sold. Whether they behave like the studied extract is not established

  Elemental content

  Frequently standardized to at least 1 mg triterpene glycosides per daily dose [2]

  Absorption

  Unknown, and not comparable brand to brand [2]

  Best for

  Widely sold. Whether they behave like the studied extract is not established [2]

• Powdered whole root and rhizomeThe traditional preparation. NCCIH notes some commercial products have contained the wrong plant species or undisclosed…

  Elemental content

  Unstandardized plant material

  Absorption

  Potency and composition vary substantially batch to batch [2]

  Best for

  The traditional preparation. NCCIH notes some commercial products have contained the wrong plant species or undisclosed mixtures with other herbs [3]

• Liquid extracts and tincturesDosed at 2 mL twice daily for the 1:1, or 2-4 mL daily for the 1:10, in the references cited

  Elemental content

  1:1 tincture in 90% alcohol, or 1:10 tincture in 60% alcohol [6][17]

  Absorption

  Alcoholic extraction; dosed by volume rather than by milligram

  Best for

  Dosed at 2 mL twice daily for the 1:1, or 2-4 mL daily for the 1:10, in the references cited [6][17]

• Common effects

  Mild gastrointestinal upset and rash are the most frequently reported [2].
  
  Clinical references also list cramping, dizziness, headache, sweating, and weight gain [6]. ^[6]

• Liver injury signal

  The main safety question here. Reports worldwide describe at least 83 cases of liver damage — hepatitis, liver failure, raised enzymes — associated with black cohosh, with no causal relationship established [2].
  
  In 2008 the US Pharmacopeia recommended labels tell users to stop and consult a practitioner given a liver disorder, or symptoms such as abdominal pain, dark urine, or jaundice [2][13].
  
  Since 2007, Australia has required labels to warn that black cohosh may harm the liver in some individuals [2]. ^[2]

• Sources disagree on whether it interacts with medications

  Kept open rather than resolved.
  
  NIH ODS states black cohosh is not known to have clinically relevant interactions with medications, while adding that this has not been systematically studied [2].
  
  The Merck Manual, Drugs.com, and a published case report each describe specific concerns: tamoxifen and irinotecan metabolism, statin effectiveness, and serotonergic risk [7][12][22]. ^[2]

• Conditions flagged as contraindications

  The Merck Manual lists aspirin sensitivity, liver disease, hormone-sensitive cancers, stroke, and high blood pressure [7].
  
  Those are blanket cautions rather than findings from trials in those groups [7]. ^[7]

• Pregnancy and breastfeeding

  The American Herbal Products Association advises pregnant women not to take black cohosh except under a provider's supervision, since its use in pregnancy has not been rigorously studied [2].
  
  NCCIH states it may not be safe during pregnancy or breastfeeding [2]. ^[2]

• Serotonergic antidepressants

  Black cohosh has serotonergic activity [22].
  
  A published case report describes serotonin toxicity and rhabdomyolysis in a woman who took it alongside long-term dual antidepressant therapy [22]. ^[22]

• Tamoxifen and irinotecan

  An in vitro study suggested black cohosh may inhibit the biotransformation or effectiveness of both chemotherapy agents [7].
  
  That is laboratory evidence, not a documented clinical event [7]. ^[7]

• Statins

  One study found black cohosh may lower the effectiveness of cholesterol-lowering statins, per the National Cancer Institute's summary [15]. ^[15]

None. Black cohosh is a wild North American perennial grown for its root and rhizome, not a food crop [2].

Those parts are processed into powders, extracts, and tinctures sold as dietary supplements. It is not eaten as produce or used as a culinary ingredient [2].

No best time of day has been established [18].

Trials most often used divided, twice-daily dosing, commonly 20-40 mg per dose, rather than specifying morning or evening [17].

Whether it needs food is also unknown. Taking it with food is sometimes suggested as a general precaution against stomach upset [18].