Black Cohosh

Supplements · Hormone Support · Supplement, Typed Supps

One of the more studied herbs for menopause symptoms.

Stage by stage

Intake (Extract capsule): Active compounds absorbed in the small intestine.
Small intestine (Absorbed): Absorbed alongside other plant compounds.
Bloodstream (Circulates): Circulates throughout the body.
Menopause symptoms (Mechanism not fully understood): Studied specifically for effects on hot flashes and related symptoms, with a mechanism that isn’t fully understood.

What the evidence supports

Reducing menopausal hot flushes and related symptoms — limited evidence. Some trials, mostly of the standardised extract Remifemin, suggest a modest effect, but reviews conclude the overall evidence is inconsistent and no clearly better than placebo in the higher-quality studies.
Evidence that it causes Rare liver injury — limited evidence. Cases of serious liver damage have been reported in people using black cohosh products. They are rare and causality is uncertain, partly because some products are adulterated with other herbs.

Typical dose

20–40 mg of standardised extract (as in Remifemin) once or twice daily

Upper limit: No established UL

Timing

With food, standard dosing.

Time to effect

Weeks: Any reported symptom change in studies.

Medication interactions

Statins: Preliminary laboratory work suggests black cohosh might affect statins. The clinical significance is unclear, but both carry a small liver-injury signal, so combining them warrants a mention to your doctor. (moderate)
Tamoxifen and breast cancer treatment: Tamoxifen has to be converted to its active form by CYP2D6 and CYP3A4, and black cohosh extract inhibits both enzymes in laboratory work, which could in principle blunt it. This has not been shown in people, but black cohosh is generally avoided in oestrogen-dependent tumours, and anyone on breast cancer treatment should clear it with their oncology team first. (moderate)
Other medicines with a liver-injury risk, and alcohol: No specific pharmacokinetic interaction is established, but rare serious liver damage has been reported with black cohosh products, so stacking it with anything else that stresses the liver is unwise. (moderate)

Common myth

“Black cohosh works by mimicking oestrogen.” In reality: Research has largely moved away from a simple oestrogen-mimicking explanation — how it works is still not fully settled.