Black Cohosh

Does black cohosh help hot flashes and other menopause symptoms?

The evidence is split. A 2023 meta-analysis of 22 randomized trials with 2,310 menopausal women found that black cohosh extracts, alone or combined with other ingredients, improved overall menopausal symptoms compared with placebo, with a smaller effect on hot flashes. Dropout rates were similar to placebo. 1

A 2012 Cochrane review of 16 trials in 2,027 women, at a median dose of 40 mg per day for an average of 23 weeks, found no significant difference from placebo in hot-flash frequency (3 trials, 393 women) or symptom scores (4 trials, 357 women). Hormone therapy worked better than black cohosh. The authors judged the evidence insufficient and trial quality generally unclear. 2

The US HALT trial gave 351 women aged 45 to 55 black cohosh at 160 mg daily, a multibotanical, hormone therapy or placebo for one year. Vasomotor symptoms did not differ between any herbal regimen and placebo, while hormone therapy cut about four symptoms per day. 3

Results look better for one specific product type, the isopropanolic extract. A meta-analysis of six placebo-controlled trials found it superior to placebo, with larger effects at higher doses. Several authors of that analysis worked for the manufacturer of this extract. 4 5

A 2025 evidence report by the German institute IQWiG, prepared for the German menopause guideline, found 7 eligible trials with usable data from 4. Across all stages of menopause, black cohosh reduced the burden of vasomotor symptoms after 3 to 6 months compared with placebo at moderate certainty; in one trial of postmenopausal women only, there was no difference after 6 months. 6

The EU herbal committee, after reviewing about 20 clinical studies with more than 6,000 treated women, concluded that certain dry extracts can be used for hot flushes and profuse sweating. Reviews attribute part of the disagreement between trials to differences in extracts, doses and study populations. 5 7

Does it help hot flashes after breast cancer?

Open-label and observational studies report fewer hot flashes in breast cancer patients taking black cohosh, but two randomized, placebo-controlled trials in women on tamoxifen or raloxifene found no difference from placebo. One of them, a crossover trial in 131 women, found no difference after 8 weeks. 5

A randomized trial of 85 breast cancer patients starting hormone-suppressing LHRH analogues found lower menopause scores over 12 weeks when black cohosh was added, but it had no placebo. NCCIH calls the effect on treatment-related hot flashes uncertain. 5 8 9

Does black cohosh help mood or anxiety during menopause?

An older review of botanicals for menopausal mood reported that black cohosh reduced depression and anxiety in all studies it covered. 10

Newer pooled data do not confirm this. The 2023 meta-analysis found no significant improvement in anxiety or depressive symptoms, and the IQWiG report found no difference in depressive symptoms after 3 to 6 months and no usable data on anxiety. 1 6

Does black cohosh improve sleep?

In a 6-month Chinese trial, 48 postmenopausal women with sleep complaints took black cohosh or placebo; 42 finished. Sleep lab recordings showed higher sleep efficiency and about 16% less time awake after falling asleep. The questionnaire score only tended to improve. 11

The IQWiG report, looking at subjective sleep quality in that trial, found no statistically significant difference at low certainty. 6

Does black cohosh protect bone?

In a 12-week German trial in 62 postmenopausal women, a black cohosh extract (40 mg herbal drug per day) changed blood markers in a direction suggesting more bone formation, while conjugated estrogens reduced bone breakdown markers. 12

Bone density itself has rarely been measured. In the Erlangen TRACE trial, 128 early postmenopausal women did an exercise program with or without 40 mg black cohosh daily. Exercise maintained spine bone density, and adding black cohosh did not improve this. 13

Does it help fertility in polycystic ovary syndrome?

A 2021 systematic review found two eligible randomized trials plus a few further records. Compared with clomiphene, black cohosh improved hormone measures and endometrial thickness, and three trials reported higher pregnancy rates with black cohosh plus clomiphene. The trials had several risk-of-bias problems, and the authors found no high-quality evidence for better pregnancy rates. 14

Menstrual cramps, PMS and treatment-induced low estrogen

NCCIH finds not enough reliable data to show whether black cohosh works for uses other than menopause symptoms, which includes menstrual cramps and premenstrual syndrome. 9

A Chinese-language review of 7 trials with 745 women with endometriosis found that black cohosh eased menopause-like symptoms caused by GnRH agonist treatment after surgery, without changing hormone levels. The authors called the evidence limited. 15

What the evidence does not show

Black cohosh is not a plant estrogen in the usual sense: clinical studies of common extracts found no change in estradiol, FSH or LH, and no estrogen-like effect on breast or endometrial tissue. 5 16

Compared directly, hormone therapy relieved hot flashes and menopausal symptoms more than black cohosh did. 2 3

This page does not review black cohosh for inflammation, joint pain, skin, stress or general health, where no trials of usable quality were found.

Who was studied, and the limits

Almost all trials enrolled perimenopausal or postmenopausal women, typically for 3 to 12 months. Products differ in solvent, extract ratio and dose, and many trials were small or poorly reported, which makes results hard to combine. 2 5 6

Placebo responses in hot-flash trials are large, so open-label results can overstate the effect. Several positive analyses of the isopropanolic extract were written by manufacturer staff. 4 5